mirror of https://github.com/FFmpeg/FFmpeg.git
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
3495 lines
97 KiB
3495 lines
97 KiB
@chapter Filtergraph description |
|
@c man begin FILTERGRAPH DESCRIPTION |
|
|
|
A filtergraph is a directed graph of connected filters. It can contain |
|
cycles, and there can be multiple links between a pair of |
|
filters. Each link has one input pad on one side connecting it to one |
|
filter from which it takes its input, and one output pad on the other |
|
side connecting it to the one filter accepting its output. |
|
|
|
Each filter in a filtergraph is an instance of a filter class |
|
registered in the application, which defines the features and the |
|
number of input and output pads of the filter. |
|
|
|
A filter with no input pads is called a "source", a filter with no |
|
output pads is called a "sink". |
|
|
|
@section Filtergraph syntax |
|
|
|
A filtergraph can be represented using a textual representation, which |
|
is recognized by the @code{-vf} option of the ff* |
|
tools, and by the @code{avfilter_graph_parse()} function defined in |
|
@file{libavfilter/avfiltergraph.h}. |
|
|
|
A filterchain consists of a sequence of connected filters, each one |
|
connected to the previous one in the sequence. A filterchain is |
|
represented by a list of ","-separated filter descriptions. |
|
|
|
A filtergraph consists of a sequence of filterchains. A sequence of |
|
filterchains is represented by a list of ";"-separated filterchain |
|
descriptions. |
|
|
|
A filter is represented by a string of the form: |
|
[@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}] |
|
|
|
@var{filter_name} is the name of the filter class of which the |
|
described filter is an instance of, and has to be the name of one of |
|
the filter classes registered in the program. |
|
The name of the filter class is optionally followed by a string |
|
"=@var{arguments}". |
|
|
|
@var{arguments} is a string which contains the parameters used to |
|
initialize the filter instance, and are described in the filter |
|
descriptions below. |
|
|
|
The list of arguments can be quoted using the character "'" as initial |
|
and ending mark, and the character '\' for escaping the characters |
|
within the quoted text; otherwise the argument string is considered |
|
terminated when the next special character (belonging to the set |
|
"[]=;,") is encountered. |
|
|
|
The name and arguments of the filter are optionally preceded and |
|
followed by a list of link labels. |
|
A link label allows to name a link and associate it to a filter output |
|
or input pad. The preceding labels @var{in_link_1} |
|
... @var{in_link_N}, are associated to the filter input pads, |
|
the following labels @var{out_link_1} ... @var{out_link_M}, are |
|
associated to the output pads. |
|
|
|
When two link labels with the same name are found in the |
|
filtergraph, a link between the corresponding input and output pad is |
|
created. |
|
|
|
If an output pad is not labelled, it is linked by default to the first |
|
unlabelled input pad of the next filter in the filterchain. |
|
For example in the filterchain: |
|
@example |
|
nullsrc, split[L1], [L2]overlay, nullsink |
|
@end example |
|
the split filter instance has two output pads, and the overlay filter |
|
instance two input pads. The first output pad of split is labelled |
|
"L1", the first input pad of overlay is labelled "L2", and the second |
|
output pad of split is linked to the second input pad of overlay, |
|
which are both unlabelled. |
|
|
|
In a complete filterchain all the unlabelled filter input and output |
|
pads must be connected. A filtergraph is considered valid if all the |
|
filter input and output pads of all the filterchains are connected. |
|
|
|
Follows a BNF description for the filtergraph syntax: |
|
@example |
|
@var{NAME} ::= sequence of alphanumeric characters and '_' |
|
@var{LINKLABEL} ::= "[" @var{NAME} "]" |
|
@var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}] |
|
@var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted) |
|
@var{FILTER} ::= [@var{LINKNAMES}] @var{NAME} ["=" @var{ARGUMENTS}] [@var{LINKNAMES}] |
|
@var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}] |
|
@var{FILTERGRAPH} ::= @var{FILTERCHAIN} [;@var{FILTERGRAPH}] |
|
@end example |
|
|
|
@c man end FILTERGRAPH DESCRIPTION |
|
|
|
@chapter Audio Filters |
|
@c man begin AUDIO FILTERS |
|
|
|
When you configure your FFmpeg build, you can disable any of the |
|
existing filters using @code{--disable-filters}. |
|
The configure output will show the audio filters included in your |
|
build. |
|
|
|
Below is a description of the currently available audio filters. |
|
|
|
@section aconvert |
|
|
|
Convert the input audio format to the specified formats. |
|
|
|
The filter accepts a string of the form: |
|
"@var{sample_format}:@var{channel_layout}". |
|
|
|
@var{sample_format} specifies the sample format, and can be a string or the |
|
corresponding numeric value defined in @file{libavutil/samplefmt.h}. Use 'p' |
|
suffix for a planar sample format. |
|
|
|
@var{channel_layout} specifies the channel layout, and can be a string |
|
or the corresponding number value defined in @file{libavutil/audioconvert.h}. |
|
|
|
The special parameter "auto", signifies that the filter will |
|
automatically select the output format depending on the output filter. |
|
|
|
Some examples follow. |
|
|
|
@itemize |
|
@item |
|
Convert input to float, planar, stereo: |
|
@example |
|
aconvert=fltp:stereo |
|
@end example |
|
|
|
@item |
|
Convert input to unsigned 8-bit, automatically select out channel layout: |
|
@example |
|
aconvert=u8:auto |
|
@end example |
|
@end itemize |
|
|
|
@section aformat |
|
|
|
Convert the input audio to one of the specified formats. The framework will |
|
negotiate the most appropriate format to minimize conversions. |
|
|
|
The filter accepts three lists of formats, separated by ":", in the form: |
|
"@var{sample_formats}:@var{channel_layouts}:@var{packing_formats}". |
|
|
|
Elements in each list are separated by "," which has to be escaped in the |
|
filtergraph specification. |
|
|
|
The special parameter "all", in place of a list of elements, signifies all |
|
supported formats. |
|
|
|
Some examples follow: |
|
@example |
|
aformat=u8\\,s16:mono:packed |
|
|
|
aformat=s16:mono\\,stereo:all |
|
@end example |
|
|
|
@section amerge |
|
|
|
Merge two audio streams into a single multi-channel stream. |
|
|
|
This filter does not need any argument. |
|
|
|
If the channel layouts of the inputs are disjoint, and therefore compatible, |
|
the channel layout of the output will be set accordingly and the channels |
|
will be reordered as necessary. If the channel layouts of the inputs are not |
|
disjoint, the output will have all the channels of the first input then all |
|
the channels of the second input, in that order, and the channel layout of |
|
the output will be the default value corresponding to the total number of |
|
channels. |
|
|
|
For example, if the first input is in 2.1 (FL+FR+LF) and the second input |
|
is FC+BL+BR, then the output will be in 5.1, with the channels in the |
|
following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the |
|
first input, b1 is the first channel of the second input). |
|
|
|
On the other hand, if both input are in stereo, the output channels will be |
|
in the default order: a1, a2, b1, b2, and the channel layout will be |
|
arbitrarily set to 4.0, which may or may not be the expected value. |
|
|
|
Both inputs must have the same sample rate, format and packing. |
|
|
|
If inputs do not have the same duration, the output will stop with the |
|
shortest. |
|
|
|
Example: merge two mono files into a stereo stream: |
|
@example |
|
amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge |
|
@end example |
|
|
|
If you need to do multiple merges (for instance multiple mono audio streams in |
|
a single video media), you can do: |
|
@example |
|
ffmpeg -f lavfi -i " |
|
amovie=input.mkv:si=0 [a0]; |
|
amovie=input.mkv:si=1 [a1]; |
|
amovie=input.mkv:si=2 [a2]; |
|
amovie=input.mkv:si=3 [a3]; |
|
amovie=input.mkv:si=4 [a4]; |
|
amovie=input.mkv:si=5 [a5]; |
|
[a0][a1] amerge [x0]; |
|
[x0][a2] amerge [x1]; |
|
[x1][a3] amerge [x2]; |
|
[x2][a4] amerge [x3]; |
|
[x3][a5] amerge" -c:a pcm_s16le output.mkv |
|
@end example |
|
|
|
@section anull |
|
|
|
Pass the audio source unchanged to the output. |
|
|
|
@section aresample |
|
|
|
Resample the input audio to the specified sample rate. |
|
|
|
The filter accepts exactly one parameter, the output sample rate. If not |
|
specified then the filter will automatically convert between its input |
|
and output sample rates. |
|
|
|
For example, to resample the input audio to 44100Hz: |
|
@example |
|
aresample=44100 |
|
@end example |
|
|
|
@section ashowinfo |
|
|
|
Show a line containing various information for each input audio frame. |
|
The input audio is not modified. |
|
|
|
The shown line contains a sequence of key/value pairs of the form |
|
@var{key}:@var{value}. |
|
|
|
A description of each shown parameter follows: |
|
|
|
@table @option |
|
@item n |
|
sequential number of the input frame, starting from 0 |
|
|
|
@item pts |
|
presentation TimeStamp of the input frame, expressed as a number of |
|
time base units. The time base unit depends on the filter input pad, and |
|
is usually 1/@var{sample_rate}. |
|
|
|
@item pts_time |
|
presentation TimeStamp of the input frame, expressed as a number of |
|
seconds |
|
|
|
@item pos |
|
position of the frame in the input stream, -1 if this information in |
|
unavailable and/or meaningless (for example in case of synthetic audio) |
|
|
|
@item fmt |
|
sample format name |
|
|
|
@item chlayout |
|
channel layout description |
|
|
|
@item nb_samples |
|
number of samples (per each channel) contained in the filtered frame |
|
|
|
@item rate |
|
sample rate for the audio frame |
|
|
|
@item planar |
|
if the packing format is planar, 0 if packed |
|
|
|
@item checksum |
|
Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame |
|
|
|
@item plane_checksum |
|
Adler-32 checksum (printed in hexadecimal) for each input frame plane, |
|
expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3} @var{c4} @var{c5} |
|
@var{c6} @var{c7}]" |
|
@end table |
|
|
|
@section asplit |
|
|
|
Pass on the input audio to two outputs. Both outputs are identical to |
|
the input audio. |
|
|
|
For example: |
|
@example |
|
[in] asplit[out0], showaudio[out1] |
|
@end example |
|
|
|
will create two separate outputs from the same input, one cropped and |
|
one padded. |
|
|
|
@section astreamsync |
|
|
|
Forward two audio streams and control the order the buffers are forwarded. |
|
|
|
The argument to the filter is an expression deciding which stream should be |
|
forwarded next: if the result is negative, the first stream is forwarded; if |
|
the result is positive or zero, the second stream is forwarded. It can use |
|
the following variables: |
|
|
|
@table @var |
|
@item b1 b2 |
|
number of buffers forwarded so far on each stream |
|
@item s1 s2 |
|
number of samples forwarded so far on each stream |
|
@item t1 t2 |
|
current timestamp of each stream |
|
@end table |
|
|
|
The default value is @code{t1-t2}, which means to always forward the stream |
|
that has a smaller timestamp. |
|
|
|
Example: stress-test @code{amerge} by randomly sending buffers on the wrong |
|
input, while avoiding too much of a desynchronization: |
|
@example |
|
amovie=file.ogg [a] ; amovie=file.mp3 [b] ; |
|
[a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ; |
|
[a2] [b2] amerge |
|
@end example |
|
|
|
@section earwax |
|
|
|
Make audio easier to listen to on headphones. |
|
|
|
This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio |
|
so that when listened to on headphones the stereo image is moved from |
|
inside your head (standard for headphones) to outside and in front of |
|
the listener (standard for speakers). |
|
|
|
Ported from SoX. |
|
|
|
@section pan |
|
|
|
Mix channels with specific gain levels. The filter accepts the output |
|
channel layout followed by a set of channels definitions. |
|
|
|
This filter is also designed to remap efficiently the channels of an audio |
|
stream. |
|
|
|
The filter accepts parameters of the form: |
|
"@var{l}:@var{outdef}:@var{outdef}:..." |
|
|
|
@table @option |
|
@item l |
|
output channel layout or number of channels |
|
|
|
@item outdef |
|
output channel specification, of the form: |
|
"@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]" |
|
|
|
@item out_name |
|
output channel to define, either a channel name (FL, FR, etc.) or a channel |
|
number (c0, c1, etc.) |
|
|
|
@item gain |
|
multiplicative coefficient for the channel, 1 leaving the volume unchanged |
|
|
|
@item in_name |
|
input channel to use, see out_name for details; it is not possible to mix |
|
named and numbered input channels |
|
@end table |
|
|
|
If the `=' in a channel specification is replaced by `<', then the gains for |
|
that specification will be renormalized so that the total is 1, thus |
|
avoiding clipping noise. |
|
|
|
@subsection Mixing examples |
|
|
|
For example, if you want to down-mix from stereo to mono, but with a bigger |
|
factor for the left channel: |
|
@example |
|
pan=1:c0=0.9*c0+0.1*c1 |
|
@end example |
|
|
|
A customized down-mix to stereo that works automatically for 3-, 4-, 5- and |
|
7-channels surround: |
|
@example |
|
pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR |
|
@end example |
|
|
|
Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system |
|
that should be preferred (see "-ac" option) unless you have very specific |
|
needs. |
|
|
|
@subsection Remapping examples |
|
|
|
The channel remapping will be effective if, and only if: |
|
|
|
@itemize |
|
@item gain coefficients are zeroes or ones, |
|
@item only one input per channel output, |
|
@end itemize |
|
|
|
If all these conditions are satisfied, the filter will notify the user ("Pure |
|
channel mapping detected"), and use an optimized and lossless method to do the |
|
remapping. |
|
|
|
For example, if you have a 5.1 source and want a stereo audio stream by |
|
dropping the extra channels: |
|
@example |
|
pan="stereo: c0=FL : c1=FR" |
|
@end example |
|
|
|
Given the same source, you can also switch front left and front right channels |
|
and keep the input channel layout: |
|
@example |
|
pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5" |
|
@end example |
|
|
|
If the input is a stereo audio stream, you can mute the front left channel (and |
|
still keep the stereo channel layout) with: |
|
@example |
|
pan="stereo:c1=c1" |
|
@end example |
|
|
|
Still with a stereo audio stream input, you can copy the right channel in both |
|
front left and right: |
|
@example |
|
pan="stereo: c0=FR : c1=FR" |
|
@end example |
|
|
|
@section silencedetect |
|
|
|
Detect silence in an audio stream. |
|
|
|
This filter logs a message when it detects that the input audio volume is less |
|
or equal to a noise tolerance value for a duration greater or equal to the |
|
minimum detected noise duration. |
|
|
|
The printed times and duration are expressed in seconds. |
|
|
|
@table @option |
|
@item duration, d |
|
Set silence duration until notification (default is 2 seconds). |
|
|
|
@item noise, n |
|
Set noise tolerance. Can be specified in dB (in case "dB" is appended to the |
|
specified value) or amplitude ratio. Default is -60dB, or 0.001. |
|
@end table |
|
|
|
Detect 5 seconds of silence with -50dB noise tolerance: |
|
@example |
|
silencedetect=n=-50dB:d=5 |
|
@end example |
|
|
|
Complete example with @command{ffmpeg} to detect silence with 0.0001 noise |
|
tolerance in @file{silence.mp3}: |
|
@example |
|
ffmpeg -f lavfi -i amovie=silence.mp3,silencedetect=noise=0.0001 -f null - |
|
@end example |
|
|
|
@section volume |
|
|
|
Adjust the input audio volume. |
|
|
|
The filter accepts exactly one parameter @var{vol}, which expresses |
|
how the audio volume will be increased or decreased. |
|
|
|
Output values are clipped to the maximum value. |
|
|
|
If @var{vol} is expressed as a decimal number, the output audio |
|
volume is given by the relation: |
|
@example |
|
@var{output_volume} = @var{vol} * @var{input_volume} |
|
@end example |
|
|
|
If @var{vol} is expressed as a decimal number followed by the string |
|
"dB", the value represents the requested change in decibels of the |
|
input audio power, and the output audio volume is given by the |
|
relation: |
|
@example |
|
@var{output_volume} = 10^(@var{vol}/20) * @var{input_volume} |
|
@end example |
|
|
|
Otherwise @var{vol} is considered an expression and its evaluated |
|
value is used for computing the output audio volume according to the |
|
first relation. |
|
|
|
Default value for @var{vol} is 1.0. |
|
|
|
@subsection Examples |
|
|
|
@itemize |
|
@item |
|
Half the input audio volume: |
|
@example |
|
volume=0.5 |
|
@end example |
|
|
|
The above example is equivalent to: |
|
@example |
|
volume=1/2 |
|
@end example |
|
|
|
@item |
|
Decrease input audio power by 12 decibels: |
|
@example |
|
volume=-12dB |
|
@end example |
|
@end itemize |
|
|
|
@c man end AUDIO FILTERS |
|
|
|
@chapter Audio Sources |
|
@c man begin AUDIO SOURCES |
|
|
|
Below is a description of the currently available audio sources. |
|
|
|
@section abuffer |
|
|
|
Buffer audio frames, and make them available to the filter chain. |
|
|
|
This source is mainly intended for a programmatic use, in particular |
|
through the interface defined in @file{libavfilter/asrc_abuffer.h}. |
|
|
|
It accepts the following mandatory parameters: |
|
@var{sample_rate}:@var{sample_fmt}:@var{channel_layout}:@var{packing} |
|
|
|
@table @option |
|
|
|
@item sample_rate |
|
The sample rate of the incoming audio buffers. |
|
|
|
@item sample_fmt |
|
The sample format of the incoming audio buffers. |
|
Either a sample format name or its corresponging integer representation from |
|
the enum AVSampleFormat in @file{libavutil/samplefmt.h} |
|
|
|
@item channel_layout |
|
The channel layout of the incoming audio buffers. |
|
Either a channel layout name from channel_layout_map in |
|
@file{libavutil/audioconvert.c} or its corresponding integer representation |
|
from the AV_CH_LAYOUT_* macros in @file{libavutil/audioconvert.h} |
|
|
|
@item packing |
|
Either "packed" or "planar", or their integer representation: 0 or 1 |
|
respectively. |
|
|
|
@end table |
|
|
|
For example: |
|
@example |
|
abuffer=44100:s16:stereo:planar |
|
@end example |
|
|
|
will instruct the source to accept planar 16bit signed stereo at 44100Hz. |
|
Since the sample format with name "s16" corresponds to the number |
|
1 and the "stereo" channel layout corresponds to the value 0x3, this is |
|
equivalent to: |
|
@example |
|
abuffer=44100:1:0x3:1 |
|
@end example |
|
|
|
@section aevalsrc |
|
|
|
Generate an audio signal specified by an expression. |
|
|
|
This source accepts in input one or more expressions (one for each |
|
channel), which are evaluated and used to generate a corresponding |
|
audio signal. |
|
|
|
It accepts the syntax: @var{exprs}[::@var{options}]. |
|
@var{exprs} is a list of expressions separated by ":", one for each |
|
separate channel. The output channel layout depends on the number of |
|
provided expressions, up to 8 channels are supported. |
|
|
|
@var{options} is an optional sequence of @var{key}=@var{value} pairs, |
|
separated by ":". |
|
|
|
The description of the accepted options follows. |
|
|
|
@table @option |
|
|
|
@item duration, d |
|
Set the minimum duration of the sourced audio. See the function |
|
@code{av_parse_time()} for the accepted format. |
|
Note that the resulting duration may be greater than the specified |
|
duration, as the generated audio is always cut at the end of a |
|
complete frame. |
|
|
|
If not specified, or the expressed duration is negative, the audio is |
|
supposed to be generated forever. |
|
|
|
@item nb_samples, n |
|
Set the number of samples per channel per each output frame, |
|
default to 1024. |
|
|
|
@item sample_rate, s |
|
Specify the sample rate, default to 44100. |
|
@end table |
|
|
|
Each expression in @var{exprs} can contain the following constants: |
|
|
|
@table @option |
|
@item n |
|
number of the evaluated sample, starting from 0 |
|
|
|
@item t |
|
time of the evaluated sample expressed in seconds, starting from 0 |
|
|
|
@item s |
|
sample rate |
|
|
|
@end table |
|
|
|
@subsection Examples |
|
|
|
@itemize |
|
|
|
@item |
|
Generate silence: |
|
@example |
|
aevalsrc=0 |
|
@end example |
|
|
|
@item |
|
|
|
Generate a sin signal with frequency of 440 Hz, set sample rate to |
|
8000 Hz: |
|
@example |
|
aevalsrc="sin(440*2*PI*t)::s=8000" |
|
@end example |
|
|
|
@item |
|
Generate white noise: |
|
@example |
|
aevalsrc="-2+random(0)" |
|
@end example |
|
|
|
@item |
|
Generate an amplitude modulated signal: |
|
@example |
|
aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)" |
|
@end example |
|
|
|
@item |
|
Generate 2.5 Hz binaural beats on a 360 Hz carrier: |
|
@example |
|
aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)" |
|
@end example |
|
|
|
@end itemize |
|
|
|
@section amovie |
|
|
|
Read an audio stream from a movie container. |
|
|
|
It accepts the syntax: @var{movie_name}[:@var{options}] where |
|
@var{movie_name} is the name of the resource to read (not necessarily |
|
a file but also a device or a stream accessed through some protocol), |
|
and @var{options} is an optional sequence of @var{key}=@var{value} |
|
pairs, separated by ":". |
|
|
|
The description of the accepted options follows. |
|
|
|
@table @option |
|
|
|
@item format_name, f |
|
Specify the format assumed for the movie to read, and can be either |
|
the name of a container or an input device. If not specified the |
|
format is guessed from @var{movie_name} or by probing. |
|
|
|
@item seek_point, sp |
|
Specify the seek point in seconds, the frames will be output |
|
starting from this seek point, the parameter is evaluated with |
|
@code{av_strtod} so the numerical value may be suffixed by an IS |
|
postfix. Default value is "0". |
|
|
|
@item stream_index, si |
|
Specify the index of the audio stream to read. If the value is -1, |
|
the best suited audio stream will be automatically selected. Default |
|
value is "-1". |
|
|
|
@end table |
|
|
|
@section anullsrc |
|
|
|
Null audio source, return unprocessed audio frames. It is mainly useful |
|
as a template and to be employed in analysis / debugging tools, or as |
|
the source for filters which ignore the input data (for example the sox |
|
synth filter). |
|
|
|
It accepts an optional sequence of @var{key}=@var{value} pairs, |
|
separated by ":". |
|
|
|
The description of the accepted options follows. |
|
|
|
@table @option |
|
|
|
@item sample_rate, s |
|
Specify the sample rate, and defaults to 44100. |
|
|
|
@item channel_layout, cl |
|
|
|
Specify the channel layout, and can be either an integer or a string |
|
representing a channel layout. The default value of @var{channel_layout} |
|
is "stereo". |
|
|
|
Check the channel_layout_map definition in |
|
@file{libavcodec/audioconvert.c} for the mapping between strings and |
|
channel layout values. |
|
|
|
@item nb_samples, n |
|
Set the number of samples per requested frames. |
|
|
|
@end table |
|
|
|
Follow some examples: |
|
@example |
|
# set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO. |
|
anullsrc=r=48000:cl=4 |
|
|
|
# same as |
|
anullsrc=r=48000:cl=mono |
|
@end example |
|
|
|
@c man end AUDIO SOURCES |
|
|
|
@chapter Audio Sinks |
|
@c man begin AUDIO SINKS |
|
|
|
Below is a description of the currently available audio sinks. |
|
|
|
@section abuffersink |
|
|
|
Buffer audio frames, and make them available to the end of filter chain. |
|
|
|
This sink is mainly intended for programmatic use, in particular |
|
through the interface defined in @file{libavfilter/buffersink.h}. |
|
|
|
It requires a pointer to an AVABufferSinkContext structure, which |
|
defines the incoming buffers' formats, to be passed as the opaque |
|
parameter to @code{avfilter_init_filter} for initialization. |
|
|
|
@section anullsink |
|
|
|
Null audio sink, do absolutely nothing with the input audio. It is |
|
mainly useful as a template and to be employed in analysis / debugging |
|
tools. |
|
|
|
@c man end AUDIO SINKS |
|
|
|
@chapter Video Filters |
|
@c man begin VIDEO FILTERS |
|
|
|
When you configure your FFmpeg build, you can disable any of the |
|
existing filters using @code{--disable-filters}. |
|
The configure output will show the video filters included in your |
|
build. |
|
|
|
Below is a description of the currently available video filters. |
|
|
|
@section ass |
|
|
|
Draw ASS (Advanced Substation Alpha) subtitles on top of input video |
|
using the libass library. |
|
|
|
To enable compilation of this filter you need to configure FFmpeg with |
|
@code{--enable-libass}. |
|
|
|
This filter accepts the syntax: @var{ass_filename}[:@var{options}], |
|
where @var{ass_filename} is the filename of the ASS file to read, and |
|
@var{options} is an optional sequence of @var{key}=@var{value} pairs, |
|
separated by ":". |
|
|
|
A description of the accepted options follows. |
|
|
|
@table @option |
|
@item original_size |
|
Specifies the size of the original video, the video for which the ASS file |
|
was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is |
|
necessary to correctly scale the fonts if the aspect ratio has been changed. |
|
@end table |
|
|
|
For example, to render the file @file{sub.ass} on top of the input |
|
video, use the command: |
|
@example |
|
ass=sub.ass |
|
@end example |
|
|
|
@section bbox |
|
|
|
Compute the bounding box for the non-black pixels in the input frame |
|
luminance plane. |
|
|
|
This filter computes the bounding box containing all the pixels with a |
|
luminance value greater than the minimum allowed value. |
|
The parameters describing the bounding box are printed on the filter |
|
log. |
|
|
|
@section blackdetect |
|
|
|
Detect video intervals that are (almost) completely black. Can be |
|
useful to detect chapter transitions, commercials, or invalid |
|
recordings. Output lines contains the time for the start, end and |
|
duration of the detected black interval expressed in seconds. |
|
|
|
In order to display the output lines, you need to set the loglevel at |
|
least to the AV_LOG_INFO value. |
|
|
|
This filter accepts a list of options in the form of |
|
@var{key}=@var{value} pairs separated by ":". A description of the |
|
accepted options follows. |
|
|
|
@table @option |
|
@item black_min_duration, d |
|
Set the minimum detected black duration expressed in seconds. It must |
|
be a non-negative floating point number. |
|
|
|
Default value is 2.0. |
|
|
|
@item picture_black_ratio_th, pic_th |
|
Set the threshold for considering a picture "black". |
|
Express the minimum value for the ratio: |
|
@example |
|
@var{nb_black_pixels} / @var{nb_pixels} |
|
@end example |
|
|
|
for which a picture is considered black. |
|
Default value is 0.98. |
|
|
|
@item pixel_black_th, pix_th |
|
Set the threshold for considering a pixel "black". |
|
|
|
The threshold expresses the maximum pixel luminance value for which a |
|
pixel is considered "black". The provided value is scaled according to |
|
the following equation: |
|
@example |
|
@var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size} |
|
@end example |
|
|
|
@var{luminance_range_size} and @var{luminance_minimum_value} depend on |
|
the input video format, the range is [0-255] for YUV full-range |
|
formats and [16-235] for YUV non full-range formats. |
|
|
|
Default value is 0.10. |
|
@end table |
|
|
|
The following example sets the maximum pixel threshold to the minimum |
|
value, and detects only black intervals of 2 or more seconds: |
|
@example |
|
blackdetect=d=2:pix_th=0.00 |
|
@end example |
|
|
|
@section blackframe |
|
|
|
Detect frames that are (almost) completely black. Can be useful to |
|
detect chapter transitions or commercials. Output lines consist of |
|
the frame number of the detected frame, the percentage of blackness, |
|
the position in the file if known or -1 and the timestamp in seconds. |
|
|
|
In order to display the output lines, you need to set the loglevel at |
|
least to the AV_LOG_INFO value. |
|
|
|
The filter accepts the syntax: |
|
@example |
|
blackframe[=@var{amount}:[@var{threshold}]] |
|
@end example |
|
|
|
@var{amount} is the percentage of the pixels that have to be below the |
|
threshold, and defaults to 98. |
|
|
|
@var{threshold} is the threshold below which a pixel value is |
|
considered black, and defaults to 32. |
|
|
|
@section boxblur |
|
|
|
Apply boxblur algorithm to the input video. |
|
|
|
This filter accepts the parameters: |
|
@var{luma_radius}:@var{luma_power}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power} |
|
|
|
Chroma and alpha parameters are optional, if not specified they default |
|
to the corresponding values set for @var{luma_radius} and |
|
@var{luma_power}. |
|
|
|
@var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent |
|
the radius in pixels of the box used for blurring the corresponding |
|
input plane. They are expressions, and can contain the following |
|
constants: |
|
@table @option |
|
@item w, h |
|
the input width and height in pixels |
|
|
|
@item cw, ch |
|
the input chroma image width and height in pixels |
|
|
|
@item hsub, vsub |
|
horizontal and vertical chroma subsample values. For example for the |
|
pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1. |
|
@end table |
|
|
|
The radius must be a non-negative number, and must not be greater than |
|
the value of the expression @code{min(w,h)/2} for the luma and alpha planes, |
|
and of @code{min(cw,ch)/2} for the chroma planes. |
|
|
|
@var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent |
|
how many times the boxblur filter is applied to the corresponding |
|
plane. |
|
|
|
Some examples follow: |
|
|
|
@itemize |
|
|
|
@item |
|
Apply a boxblur filter with luma, chroma, and alpha radius |
|
set to 2: |
|
@example |
|
boxblur=2:1 |
|
@end example |
|
|
|
@item |
|
Set luma radius to 2, alpha and chroma radius to 0 |
|
@example |
|
boxblur=2:1:0:0:0:0 |
|
@end example |
|
|
|
@item |
|
Set luma and chroma radius to a fraction of the video dimension |
|
@example |
|
boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1 |
|
@end example |
|
|
|
@end itemize |
|
|
|
@section colormatrix |
|
|
|
The colormatrix filter allows conversion between any of the following color |
|
space: BT.709 (@var{bt709}), BT.601 (@var{bt601}), SMPTE-240M (@var{smpte240m}) |
|
and FCC (@var{fcc}). |
|
|
|
The syntax of the parameters is @var{source}:@var{destination}: |
|
|
|
@example |
|
colormatrix=bt601:smpte240m |
|
@end example |
|
|
|
@section copy |
|
|
|
Copy the input source unchanged to the output. Mainly useful for |
|
testing purposes. |
|
|
|
@section crop |
|
|
|
Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect} |
|
|
|
The @var{keep_aspect} parameter is optional, if specified and set to a |
|
non-zero value will force the output display aspect ratio to be the |
|
same of the input, by changing the output sample aspect ratio. |
|
|
|
The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are |
|
expressions containing the following constants: |
|
|
|
@table @option |
|
@item x, y |
|
the computed values for @var{x} and @var{y}. They are evaluated for |
|
each new frame. |
|
|
|
@item in_w, in_h |
|
the input width and height |
|
|
|
@item iw, ih |
|
same as @var{in_w} and @var{in_h} |
|
|
|
@item out_w, out_h |
|
the output (cropped) width and height |
|
|
|
@item ow, oh |
|
same as @var{out_w} and @var{out_h} |
|
|
|
@item a |
|
same as @var{iw} / @var{ih} |
|
|
|
@item sar |
|
input sample aspect ratio |
|
|
|
@item dar |
|
input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar} |
|
|
|
@item hsub, vsub |
|
horizontal and vertical chroma subsample values. For example for the |
|
pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1. |
|
|
|
@item n |
|
the number of input frame, starting from 0 |
|
|
|
@item pos |
|
the position in the file of the input frame, NAN if unknown |
|
|
|
@item t |
|
timestamp expressed in seconds, NAN if the input timestamp is unknown |
|
|
|
@end table |
|
|
|
The @var{out_w} and @var{out_h} parameters specify the expressions for |
|
the width and height of the output (cropped) video. They are |
|
evaluated just at the configuration of the filter. |
|
|
|
The default value of @var{out_w} is "in_w", and the default value of |
|
@var{out_h} is "in_h". |
|
|
|
The expression for @var{out_w} may depend on the value of @var{out_h}, |
|
and the expression for @var{out_h} may depend on @var{out_w}, but they |
|
cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are |
|
evaluated after @var{out_w} and @var{out_h}. |
|
|
|
The @var{x} and @var{y} parameters specify the expressions for the |
|
position of the top-left corner of the output (non-cropped) area. They |
|
are evaluated for each frame. If the evaluated value is not valid, it |
|
is approximated to the nearest valid value. |
|
|
|
The default value of @var{x} is "(in_w-out_w)/2", and the default |
|
value for @var{y} is "(in_h-out_h)/2", which set the cropped area at |
|
the center of the input image. |
|
|
|
The expression for @var{x} may depend on @var{y}, and the expression |
|
for @var{y} may depend on @var{x}. |
|
|
|
Follow some examples: |
|
@example |
|
# crop the central input area with size 100x100 |
|
crop=100:100 |
|
|
|
# crop the central input area with size 2/3 of the input video |
|
"crop=2/3*in_w:2/3*in_h" |
|
|
|
# crop the input video central square |
|
crop=in_h |
|
|
|
# delimit the rectangle with the top-left corner placed at position |
|
# 100:100 and the right-bottom corner corresponding to the right-bottom |
|
# corner of the input image. |
|
crop=in_w-100:in_h-100:100:100 |
|
|
|
# crop 10 pixels from the left and right borders, and 20 pixels from |
|
# the top and bottom borders |
|
"crop=in_w-2*10:in_h-2*20" |
|
|
|
# keep only the bottom right quarter of the input image |
|
"crop=in_w/2:in_h/2:in_w/2:in_h/2" |
|
|
|
# crop height for getting Greek harmony |
|
"crop=in_w:1/PHI*in_w" |
|
|
|
# trembling effect |
|
"crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(n/10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(n/7)" |
|
|
|
# erratic camera effect depending on timestamp |
|
"crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)" |
|
|
|
# set x depending on the value of y |
|
"crop=in_w/2:in_h/2:y:10+10*sin(n/10)" |
|
@end example |
|
|
|
@section cropdetect |
|
|
|
Auto-detect crop size. |
|
|
|
Calculate necessary cropping parameters and prints the recommended |
|
parameters through the logging system. The detected dimensions |
|
correspond to the non-black area of the input video. |
|
|
|
It accepts the syntax: |
|
@example |
|
cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]] |
|
@end example |
|
|
|
@table @option |
|
|
|
@item limit |
|
Threshold, which can be optionally specified from nothing (0) to |
|
everything (255), defaults to 24. |
|
|
|
@item round |
|
Value which the width/height should be divisible by, defaults to |
|
16. The offset is automatically adjusted to center the video. Use 2 to |
|
get only even dimensions (needed for 4:2:2 video). 16 is best when |
|
encoding to most video codecs. |
|
|
|
@item reset |
|
Counter that determines after how many frames cropdetect will reset |
|
the previously detected largest video area and start over to detect |
|
the current optimal crop area. Defaults to 0. |
|
|
|
This can be useful when channel logos distort the video area. 0 |
|
indicates never reset and return the largest area encountered during |
|
playback. |
|
@end table |
|
|
|
@section delogo |
|
|
|
Suppress a TV station logo by a simple interpolation of the surrounding |
|
pixels. Just set a rectangle covering the logo and watch it disappear |
|
(and sometimes something even uglier appear - your mileage may vary). |
|
|
|
The filter accepts parameters as a string of the form |
|
"@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of |
|
@var{key}=@var{value} pairs, separated by ":". |
|
|
|
The description of the accepted parameters follows. |
|
|
|
@table @option |
|
|
|
@item x, y |
|
Specify the top left corner coordinates of the logo. They must be |
|
specified. |
|
|
|
@item w, h |
|
Specify the width and height of the logo to clear. They must be |
|
specified. |
|
|
|
@item band, t |
|
Specify the thickness of the fuzzy edge of the rectangle (added to |
|
@var{w} and @var{h}). The default value is 4. |
|
|
|
@item show |
|
When set to 1, a green rectangle is drawn on the screen to simplify |
|
finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and |
|
@var{band} is set to 4. The default value is 0. |
|
|
|
@end table |
|
|
|
Some examples follow. |
|
|
|
@itemize |
|
|
|
@item |
|
Set a rectangle covering the area with top left corner coordinates 0,0 |
|
and size 100x77, setting a band of size 10: |
|
@example |
|
delogo=0:0:100:77:10 |
|
@end example |
|
|
|
@item |
|
As the previous example, but use named options: |
|
@example |
|
delogo=x=0:y=0:w=100:h=77:band=10 |
|
@end example |
|
|
|
@end itemize |
|
|
|
@section deshake |
|
|
|
Attempt to fix small changes in horizontal and/or vertical shift. This |
|
filter helps remove camera shake from hand-holding a camera, bumping a |
|
tripod, moving on a vehicle, etc. |
|
|
|
The filter accepts parameters as a string of the form |
|
"@var{x}:@var{y}:@var{w}:@var{h}:@var{rx}:@var{ry}:@var{edge}:@var{blocksize}:@var{contrast}:@var{search}:@var{filename}" |
|
|
|
A description of the accepted parameters follows. |
|
|
|
@table @option |
|
|
|
@item x, y, w, h |
|
Specify a rectangular area where to limit the search for motion |
|
vectors. |
|
If desired the search for motion vectors can be limited to a |
|
rectangular area of the frame defined by its top left corner, width |
|
and height. These parameters have the same meaning as the drawbox |
|
filter which can be used to visualise the position of the bounding |
|
box. |
|
|
|
This is useful when simultaneous movement of subjects within the frame |
|
might be confused for camera motion by the motion vector search. |
|
|
|
If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1 |
|
then the full frame is used. This allows later options to be set |
|
without specifying the bounding box for the motion vector search. |
|
|
|
Default - search the whole frame. |
|
|
|
@item rx, ry |
|
Specify the maximum extent of movement in x and y directions in the |
|
range 0-64 pixels. Default 16. |
|
|
|
@item edge |
|
Specify how to generate pixels to fill blanks at the edge of the |
|
frame. An integer from 0 to 3 as follows: |
|
@table @option |
|
@item 0 |
|
Fill zeroes at blank locations |
|
@item 1 |
|
Original image at blank locations |
|
@item 2 |
|
Extruded edge value at blank locations |
|
@item 3 |
|
Mirrored edge at blank locations |
|
@end table |
|
|
|
The default setting is mirror edge at blank locations. |
|
|
|
@item blocksize |
|
Specify the blocksize to use for motion search. Range 4-128 pixels, |
|
default 8. |
|
|
|
@item contrast |
|
Specify the contrast threshold for blocks. Only blocks with more than |
|
the specified contrast (difference between darkest and lightest |
|
pixels) will be considered. Range 1-255, default 125. |
|
|
|
@item search |
|
Specify the search strategy 0 = exhaustive search, 1 = less exhaustive |
|
search. Default - exhaustive search. |
|
|
|
@item filename |
|
If set then a detailed log of the motion search is written to the |
|
specified file. |
|
|
|
@end table |
|
|
|
@section drawbox |
|
|
|
Draw a colored box on the input image. |
|
|
|
It accepts the syntax: |
|
@example |
|
drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color} |
|
@end example |
|
|
|
@table @option |
|
|
|
@item x, y |
|
Specify the top left corner coordinates of the box. Default to 0. |
|
|
|
@item width, height |
|
Specify the width and height of the box, if 0 they are interpreted as |
|
the input width and height. Default to 0. |
|
|
|
@item color |
|
Specify the color of the box to write, it can be the name of a color |
|
(case insensitive match) or a 0xRRGGBB[AA] sequence. |
|
@end table |
|
|
|
Follow some examples: |
|
@example |
|
# draw a black box around the edge of the input image |
|
drawbox |
|
|
|
# draw a box with color red and an opacity of 50% |
|
drawbox=10:20:200:60:red@@0.5" |
|
@end example |
|
|
|
@section drawtext |
|
|
|
Draw text string or text from specified file on top of video using the |
|
libfreetype library. |
|
|
|
To enable compilation of this filter you need to configure FFmpeg with |
|
@code{--enable-libfreetype}. |
|
|
|
The filter also recognizes strftime() sequences in the provided text |
|
and expands them accordingly. Check the documentation of strftime(). |
|
|
|
The filter accepts parameters as a list of @var{key}=@var{value} pairs, |
|
separated by ":". |
|
|
|
The description of the accepted parameters follows. |
|
|
|
@table @option |
|
|
|
@item fontfile |
|
The font file to be used for drawing text. Path must be included. |
|
This parameter is mandatory. |
|
|
|
@item text |
|
The text string to be drawn. The text must be a sequence of UTF-8 |
|
encoded characters. |
|
This parameter is mandatory if no file is specified with the parameter |
|
@var{textfile}. |
|
|
|
@item textfile |
|
A text file containing text to be drawn. The text must be a sequence |
|
of UTF-8 encoded characters. |
|
|
|
This parameter is mandatory if no text string is specified with the |
|
parameter @var{text}. |
|
|
|
If both text and textfile are specified, an error is thrown. |
|
|
|
@item x, y |
|
The expressions which specify the offsets where text will be drawn |
|
within the video frame. They are relative to the top/left border of the |
|
output image. |
|
|
|
The default value of @var{x} and @var{y} is "0". |
|
|
|
See below for the list of accepted constants. |
|
|
|
@item fontsize |
|
The font size to be used for drawing text. |
|
The default value of @var{fontsize} is 16. |
|
|
|
@item fontcolor |
|
The color to be used for drawing fonts. |
|
Either a string (e.g. "red") or in 0xRRGGBB[AA] format |
|
(e.g. "0xff000033"), possibly followed by an alpha specifier. |
|
The default value of @var{fontcolor} is "black". |
|
|
|
@item boxcolor |
|
The color to be used for drawing box around text. |
|
Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format |
|
(e.g. "0xff00ff"), possibly followed by an alpha specifier. |
|
The default value of @var{boxcolor} is "white". |
|
|
|
@item box |
|
Used to draw a box around text using background color. |
|
Value should be either 1 (enable) or 0 (disable). |
|
The default value of @var{box} is 0. |
|
|
|
@item shadowx, shadowy |
|
The x and y offsets for the text shadow position with respect to the |
|
position of the text. They can be either positive or negative |
|
values. Default value for both is "0". |
|
|
|
@item shadowcolor |
|
The color to be used for drawing a shadow behind the drawn text. It |
|
can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA] |
|
form (e.g. "0xff00ff"), possibly followed by an alpha specifier. |
|
The default value of @var{shadowcolor} is "black". |
|
|
|
@item ft_load_flags |
|
Flags to be used for loading the fonts. |
|
|
|
The flags map the corresponding flags supported by libfreetype, and are |
|
a combination of the following values: |
|
@table @var |
|
@item default |
|
@item no_scale |
|
@item no_hinting |
|
@item render |
|
@item no_bitmap |
|
@item vertical_layout |
|
@item force_autohint |
|
@item crop_bitmap |
|
@item pedantic |
|
@item ignore_global_advance_width |
|
@item no_recurse |
|
@item ignore_transform |
|
@item monochrome |
|
@item linear_design |
|
@item no_autohint |
|
@item end table |
|
@end table |
|
|
|
Default value is "render". |
|
|
|
For more information consult the documentation for the FT_LOAD_* |
|
libfreetype flags. |
|
|
|
@item tabsize |
|
The size in number of spaces to use for rendering the tab. |
|
Default value is 4. |
|
|
|
@item fix_bounds |
|
If true, check and fix text coords to avoid clipping. |
|
@end table |
|
|
|
The parameters for @var{x} and @var{y} are expressions containing the |
|
following constants: |
|
|
|
@table @option |
|
@item W, H |
|
the input width and height |
|
|
|
@item tw, text_w |
|
the width of the rendered text |
|
|
|
@item th, text_h |
|
the height of the rendered text |
|
|
|
@item lh, line_h |
|
the height of each text line |
|
|
|
@item sar |
|
input sample aspect ratio |
|
|
|
@item dar |
|
input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar} |
|
|
|
@item hsub, vsub |
|
horizontal and vertical chroma subsample values. For example for the |
|
pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1. |
|
|
|
@item max_glyph_w |
|
maximum glyph width, that is the maximum width for all the glyphs |
|
contained in the rendered text |
|
|
|
@item max_glyph_h |
|
maximum glyph height, that is the maximum height for all the glyphs |
|
contained in the rendered text, it is equivalent to @var{ascent} - |
|
@var{descent}. |
|
|
|
@item max_glyph_a, ascent |
|
|
|
the maximum distance from the baseline to the highest/upper grid |
|
coordinate used to place a glyph outline point, for all the rendered |
|
glyphs. |
|
It is a positive value, due to the grid's orientation with the Y axis |
|
upwards. |
|
|
|
@item max_glyph_d, descent |
|
the maximum distance from the baseline to the lowest grid coordinate |
|
used to place a glyph outline point, for all the rendered glyphs. |
|
This is a negative value, due to the grid's orientation, with the Y axis |
|
upwards. |
|
|
|
@item n |
|
the number of input frame, starting from 0 |
|
|
|
@item t |
|
timestamp expressed in seconds, NAN if the input timestamp is unknown |
|
|
|
@item timecode |
|
initial timecode representation in "hh:mm:ss[:;.]ff" format. It can be used |
|
with or without text parameter. @var{rate} option must be specified. |
|
|
|
@item r, rate |
|
frame rate (timecode only) |
|
@end table |
|
|
|
Some examples follow. |
|
|
|
@itemize |
|
|
|
@item |
|
Draw "Test Text" with font FreeSerif, using the default values for the |
|
optional parameters. |
|
|
|
@example |
|
drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'" |
|
@end example |
|
|
|
@item |
|
Draw 'Test Text' with font FreeSerif of size 24 at position x=100 |
|
and y=50 (counting from the top-left corner of the screen), text is |
|
yellow with a red box around it. Both the text and the box have an |
|
opacity of 20%. |
|
|
|
@example |
|
drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\ |
|
x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2" |
|
@end example |
|
|
|
Note that the double quotes are not necessary if spaces are not used |
|
within the parameter list. |
|
|
|
@item |
|
Show the text at the center of the video frame: |
|
@example |
|
drawtext=fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2" |
|
@end example |
|
|
|
@item |
|
Show a text line sliding from right to left in the last row of the video |
|
frame. The file @file{LONG_LINE} is assumed to contain a single line |
|
with no newlines. |
|
@example |
|
drawtext=fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t |
|
@end example |
|
|
|
@item |
|
Show the content of file @file{CREDITS} off the bottom of the frame and scroll up. |
|
@example |
|
drawtext=fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t" |
|
@end example |
|
|
|
@item |
|
Draw a single green letter "g", at the center of the input video. |
|
The glyph baseline is placed at half screen height. |
|
@example |
|
drawtext=fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent |
|
@end example |
|
|
|
@end itemize |
|
|
|
For more information about libfreetype, check: |
|
@url{http://www.freetype.org/}. |
|
|
|
@section fade |
|
|
|
Apply fade-in/out effect to input video. |
|
|
|
It accepts the parameters: |
|
@var{type}:@var{start_frame}:@var{nb_frames}[:@var{options}] |
|
|
|
@var{type} specifies if the effect type, can be either "in" for |
|
fade-in, or "out" for a fade-out effect. |
|
|
|
@var{start_frame} specifies the number of the start frame for starting |
|
to apply the fade effect. |
|
|
|
@var{nb_frames} specifies the number of frames for which the fade |
|
effect has to last. At the end of the fade-in effect the output video |
|
will have the same intensity as the input video, at the end of the |
|
fade-out transition the output video will be completely black. |
|
|
|
@var{options} is an optional sequence of @var{key}=@var{value} pairs, |
|
separated by ":". The description of the accepted options follows. |
|
|
|
@table @option |
|
|
|
@item type, t |
|
See @var{type}. |
|
|
|
@item start_frame, s |
|
See @var{start_frame}. |
|
|
|
@item nb_frames, n |
|
See @var{nb_frames}. |
|
|
|
@item alpha |
|
If set to 1, fade only alpha channel, if one exists on the input. |
|
Default value is 0. |
|
@end table |
|
|
|
A few usage examples follow, usable too as test scenarios. |
|
@example |
|
# fade in first 30 frames of video |
|
fade=in:0:30 |
|
|
|
# fade out last 45 frames of a 200-frame video |
|
fade=out:155:45 |
|
|
|
# fade in first 25 frames and fade out last 25 frames of a 1000-frame video |
|
fade=in:0:25, fade=out:975:25 |
|
|
|
# make first 5 frames black, then fade in from frame 5-24 |
|
fade=in:5:20 |
|
|
|
# fade in alpha over first 25 frames of video |
|
fade=in:0:25:alpha=1 |
|
@end example |
|
|
|
@section fieldorder |
|
|
|
Transform the field order of the input video. |
|
|
|
It accepts one parameter which specifies the required field order that |
|
the input interlaced video will be transformed to. The parameter can |
|
assume one of the following values: |
|
|
|
@table @option |
|
@item 0 or bff |
|
output bottom field first |
|
@item 1 or tff |
|
output top field first |
|
@end table |
|
|
|
Default value is "tff". |
|
|
|
Transformation is achieved by shifting the picture content up or down |
|
by one line, and filling the remaining line with appropriate picture content. |
|
This method is consistent with most broadcast field order converters. |
|
|
|
If the input video is not flagged as being interlaced, or it is already |
|
flagged as being of the required output field order then this filter does |
|
not alter the incoming video. |
|
|
|
This filter is very useful when converting to or from PAL DV material, |
|
which is bottom field first. |
|
|
|
For example: |
|
@example |
|
ffmpeg -i in.vob -vf "fieldorder=bff" out.dv |
|
@end example |
|
|
|
@section fifo |
|
|
|
Buffer input images and send them when they are requested. |
|
|
|
This filter is mainly useful when auto-inserted by the libavfilter |
|
framework. |
|
|
|
The filter does not take parameters. |
|
|
|
@section format |
|
|
|
Convert the input video to one of the specified pixel formats. |
|
Libavfilter will try to pick one that is supported for the input to |
|
the next filter. |
|
|
|
The filter accepts a list of pixel format names, separated by ":", |
|
for example "yuv420p:monow:rgb24". |
|
|
|
Some examples follow: |
|
@example |
|
# convert the input video to the format "yuv420p" |
|
format=yuv420p |
|
|
|
# convert the input video to any of the formats in the list |
|
format=yuv420p:yuv444p:yuv410p |
|
@end example |
|
|
|
@anchor{frei0r} |
|
@section frei0r |
|
|
|
Apply a frei0r effect to the input video. |
|
|
|
To enable compilation of this filter you need to install the frei0r |
|
header and configure FFmpeg with @code{--enable-frei0r}. |
|
|
|
The filter supports the syntax: |
|
@example |
|
@var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}] |
|
@end example |
|
|
|
@var{filter_name} is the name to the frei0r effect to load. If the |
|
environment variable @env{FREI0R_PATH} is defined, the frei0r effect |
|
is searched in each one of the directories specified by the colon |
|
separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r |
|
paths, which are in this order: @file{HOME/.frei0r-1/lib/}, |
|
@file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}. |
|
|
|
@var{param1}, @var{param2}, ... , @var{paramN} specify the parameters |
|
for the frei0r effect. |
|
|
|
A frei0r effect parameter can be a boolean (whose values are specified |
|
with "y" and "n"), a double, a color (specified by the syntax |
|
@var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float |
|
numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color |
|
description), a position (specified by the syntax @var{X}/@var{Y}, |
|
@var{X} and @var{Y} being float numbers) and a string. |
|
|
|
The number and kind of parameters depend on the loaded effect. If an |
|
effect parameter is not specified the default value is set. |
|
|
|
Some examples follow: |
|
@example |
|
# apply the distort0r effect, set the first two double parameters |
|
frei0r=distort0r:0.5:0.01 |
|
|
|
# apply the colordistance effect, takes a color as first parameter |
|
frei0r=colordistance:0.2/0.3/0.4 |
|
frei0r=colordistance:violet |
|
frei0r=colordistance:0x112233 |
|
|
|
# apply the perspective effect, specify the top left and top right |
|
# image positions |
|
frei0r=perspective:0.2/0.2:0.8/0.2 |
|
@end example |
|
|
|
For more information see: |
|
@url{http://piksel.org/frei0r} |
|
|
|
@section gradfun |
|
|
|
Fix the banding artifacts that are sometimes introduced into nearly flat |
|
regions by truncation to 8bit color depth. |
|
Interpolate the gradients that should go where the bands are, and |
|
dither them. |
|
|
|
This filter is designed for playback only. Do not use it prior to |
|
lossy compression, because compression tends to lose the dither and |
|
bring back the bands. |
|
|
|
The filter takes two optional parameters, separated by ':': |
|
@var{strength}:@var{radius} |
|
|
|
@var{strength} is the maximum amount by which the filter will change |
|
any one pixel. Also the threshold for detecting nearly flat |
|
regions. Acceptable values range from .51 to 255, default value is |
|
1.2, out-of-range values will be clipped to the valid range. |
|
|
|
@var{radius} is the neighborhood to fit the gradient to. A larger |
|
radius makes for smoother gradients, but also prevents the filter from |
|
modifying the pixels near detailed regions. Acceptable values are |
|
8-32, default value is 16, out-of-range values will be clipped to the |
|
valid range. |
|
|
|
@example |
|
# default parameters |
|
gradfun=1.2:16 |
|
|
|
# omitting radius |
|
gradfun=1.2 |
|
@end example |
|
|
|
@section hflip |
|
|
|
Flip the input video horizontally. |
|
|
|
For example to horizontally flip the input video with @command{ffmpeg}: |
|
@example |
|
ffmpeg -i in.avi -vf "hflip" out.avi |
|
@end example |
|
|
|
@section hqdn3d |
|
|
|
High precision/quality 3d denoise filter. This filter aims to reduce |
|
image noise producing smooth images and making still images really |
|
still. It should enhance compressibility. |
|
|
|
It accepts the following optional parameters: |
|
@var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp} |
|
|
|
@table @option |
|
@item luma_spatial |
|
a non-negative float number which specifies spatial luma strength, |
|
defaults to 4.0 |
|
|
|
@item chroma_spatial |
|
a non-negative float number which specifies spatial chroma strength, |
|
defaults to 3.0*@var{luma_spatial}/4.0 |
|
|
|
@item luma_tmp |
|
a float number which specifies luma temporal strength, defaults to |
|
6.0*@var{luma_spatial}/4.0 |
|
|
|
@item chroma_tmp |
|
a float number which specifies chroma temporal strength, defaults to |
|
@var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial} |
|
@end table |
|
|
|
@section idet |
|
|
|
Interlaceing detect filter. This filter tries to detect if the input is |
|
interlaced or progressive. Top or bottom field first. |
|
|
|
@section lut, lutrgb, lutyuv |
|
|
|
Compute a look-up table for binding each pixel component input value |
|
to an output value, and apply it to input video. |
|
|
|
@var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb} |
|
to an RGB input video. |
|
|
|
These filters accept in input a ":"-separated list of options, which |
|
specify the expressions used for computing the lookup table for the |
|
corresponding pixel component values. |
|
|
|
The @var{lut} filter requires either YUV or RGB pixel formats in |
|
input, and accepts the options: |
|
@table @option |
|
@item c0 |
|
first pixel component |
|
@item c1 |
|
second pixel component |
|
@item c2 |
|
third pixel component |
|
@item c3 |
|
fourth pixel component, corresponds to the alpha component |
|
@end table |
|
|
|
The exact component associated to each option depends on the format in |
|
input. |
|
|
|
The @var{lutrgb} filter requires RGB pixel formats in input, and |
|
accepts the options: |
|
@table @option |
|
@item r |
|
red component |
|
@item g |
|
green component |
|
@item b |
|
blue component |
|
@item a |
|
alpha component |
|
@end table |
|
|
|
The @var{lutyuv} filter requires YUV pixel formats in input, and |
|
accepts the options: |
|
@table @option |
|
@item y |
|
Y/luminance component |
|
@item u |
|
U/Cb component |
|
@item v |
|
V/Cr component |
|
@item a |
|
alpha component |
|
@end table |
|
|
|
The expressions can contain the following constants and functions: |
|
|
|
@table @option |
|
@item w, h |
|
the input width and height |
|
|
|
@item val |
|
input value for the pixel component |
|
|
|
@item clipval |
|
the input value clipped in the @var{minval}-@var{maxval} range |
|
|
|
@item maxval |
|
maximum value for the pixel component |
|
|
|
@item minval |
|
minimum value for the pixel component |
|
|
|
@item negval |
|
the negated value for the pixel component value clipped in the |
|
@var{minval}-@var{maxval} range , it corresponds to the expression |
|
"maxval-clipval+minval" |
|
|
|
@item clip(val) |
|
the computed value in @var{val} clipped in the |
|
@var{minval}-@var{maxval} range |
|
|
|
@item gammaval(gamma) |
|
the computed gamma correction value of the pixel component value |
|
clipped in the @var{minval}-@var{maxval} range, corresponds to the |
|
expression |
|
"pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval" |
|
|
|
@end table |
|
|
|
All expressions default to "val". |
|
|
|
Some examples follow: |
|
@example |
|
# negate input video |
|
lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val" |
|
lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val" |
|
|
|
# the above is the same as |
|
lutrgb="r=negval:g=negval:b=negval" |
|
lutyuv="y=negval:u=negval:v=negval" |
|
|
|
# negate luminance |
|
lutyuv=y=negval |
|
|
|
# remove chroma components, turns the video into a graytone image |
|
lutyuv="u=128:v=128" |
|
|
|
# apply a luma burning effect |
|
lutyuv="y=2*val" |
|
|
|
# remove green and blue components |
|
lutrgb="g=0:b=0" |
|
|
|
# set a constant alpha channel value on input |
|
format=rgba,lutrgb=a="maxval-minval/2" |
|
|
|
# correct luminance gamma by a 0.5 factor |
|
lutyuv=y=gammaval(0.5) |
|
@end example |
|
|
|
@section mp |
|
|
|
Apply an MPlayer filter to the input video. |
|
|
|
This filter provides a wrapper around most of the filters of |
|
MPlayer/MEncoder. |
|
|
|
This wrapper is considered experimental. Some of the wrapped filters |
|
may not work properly and we may drop support for them, as they will |
|
be implemented natively into FFmpeg. Thus you should avoid |
|
depending on them when writing portable scripts. |
|
|
|
The filters accepts the parameters: |
|
@var{filter_name}[:=]@var{filter_params} |
|
|
|
@var{filter_name} is the name of a supported MPlayer filter, |
|
@var{filter_params} is a string containing the parameters accepted by |
|
the named filter. |
|
|
|
The list of the currently supported filters follows: |
|
@table @var |
|
@item 2xsai |
|
@item decimate |
|
@item denoise3d |
|
@item detc |
|
@item dint |
|
@item divtc |
|
@item down3dright |
|
@item dsize |
|
@item eq2 |
|
@item eq |
|
@item field |
|
@item fil |
|
@item fixpts |
|
@item framestep |
|
@item fspp |
|
@item geq |
|
@item harddup |
|
@item hqdn3d |
|
@item hue |
|
@item il |
|
@item ilpack |
|
@item ivtc |
|
@item kerndeint |
|
@item mcdeint |
|
@item mirror |
|
@item noise |
|
@item ow |
|
@item palette |
|
@item perspective |
|
@item phase |
|
@item pp7 |
|
@item pullup |
|
@item qp |
|
@item rectangle |
|
@item remove-logo |
|
@item rotate |
|
@item sab |
|
@item screenshot |
|
@item smartblur |
|
@item softpulldown |
|
@item softskip |
|
@item spp |
|
@item telecine |
|
@item tile |
|
@item tinterlace |
|
@item unsharp |
|
@item uspp |
|
@item yuvcsp |
|
@item yvu9 |
|
@end table |
|
|
|
The parameter syntax and behavior for the listed filters are the same |
|
of the corresponding MPlayer filters. For detailed instructions check |
|
the "VIDEO FILTERS" section in the MPlayer manual. |
|
|
|
Some examples follow: |
|
@example |
|
# remove a logo by interpolating the surrounding pixels |
|
mp=delogo=200:200:80:20:1 |
|
|
|
# adjust gamma, brightness, contrast |
|
mp=eq2=1.0:2:0.5 |
|
|
|
# tweak hue and saturation |
|
mp=hue=100:-10 |
|
@end example |
|
|
|
See also mplayer(1), @url{http://www.mplayerhq.hu/}. |
|
|
|
@section negate |
|
|
|
Negate input video. |
|
|
|
This filter accepts an integer in input, if non-zero it negates the |
|
alpha component (if available). The default value in input is 0. |
|
|
|
@section noformat |
|
|
|
Force libavfilter not to use any of the specified pixel formats for the |
|
input to the next filter. |
|
|
|
The filter accepts a list of pixel format names, separated by ":", |
|
for example "yuv420p:monow:rgb24". |
|
|
|
Some examples follow: |
|
@example |
|
# force libavfilter to use a format different from "yuv420p" for the |
|
# input to the vflip filter |
|
noformat=yuv420p,vflip |
|
|
|
# convert the input video to any of the formats not contained in the list |
|
noformat=yuv420p:yuv444p:yuv410p |
|
@end example |
|
|
|
@section null |
|
|
|
Pass the video source unchanged to the output. |
|
|
|
@section ocv |
|
|
|
Apply video transform using libopencv. |
|
|
|
To enable this filter install libopencv library and headers and |
|
configure FFmpeg with @code{--enable-libopencv}. |
|
|
|
The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}. |
|
|
|
@var{filter_name} is the name of the libopencv filter to apply. |
|
|
|
@var{filter_params} specifies the parameters to pass to the libopencv |
|
filter. If not specified the default values are assumed. |
|
|
|
Refer to the official libopencv documentation for more precise |
|
information: |
|
@url{http://opencv.willowgarage.com/documentation/c/image_filtering.html} |
|
|
|
Follows the list of supported libopencv filters. |
|
|
|
@anchor{dilate} |
|
@subsection dilate |
|
|
|
Dilate an image by using a specific structuring element. |
|
This filter corresponds to the libopencv function @code{cvDilate}. |
|
|
|
It accepts the parameters: @var{struct_el}:@var{nb_iterations}. |
|
|
|
@var{struct_el} represents a structuring element, and has the syntax: |
|
@var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape} |
|
|
|
@var{cols} and @var{rows} represent the number of columns and rows of |
|
the structuring element, @var{anchor_x} and @var{anchor_y} the anchor |
|
point, and @var{shape} the shape for the structuring element, and |
|
can be one of the values "rect", "cross", "ellipse", "custom". |
|
|
|
If the value for @var{shape} is "custom", it must be followed by a |
|
string of the form "=@var{filename}". The file with name |
|
@var{filename} is assumed to represent a binary image, with each |
|
printable character corresponding to a bright pixel. When a custom |
|
@var{shape} is used, @var{cols} and @var{rows} are ignored, the number |
|
or columns and rows of the read file are assumed instead. |
|
|
|
The default value for @var{struct_el} is "3x3+0x0/rect". |
|
|
|
@var{nb_iterations} specifies the number of times the transform is |
|
applied to the image, and defaults to 1. |
|
|
|
Follow some example: |
|
@example |
|
# use the default values |
|
ocv=dilate |
|
|
|
# dilate using a structuring element with a 5x5 cross, iterate two times |
|
ocv=dilate=5x5+2x2/cross:2 |
|
|
|
# read the shape from the file diamond.shape, iterate two times |
|
# the file diamond.shape may contain a pattern of characters like this: |
|
# * |
|
# *** |
|
# ***** |
|
# *** |
|
# * |
|
# the specified cols and rows are ignored (but not the anchor point coordinates) |
|
ocv=0x0+2x2/custom=diamond.shape:2 |
|
@end example |
|
|
|
@subsection erode |
|
|
|
Erode an image by using a specific structuring element. |
|
This filter corresponds to the libopencv function @code{cvErode}. |
|
|
|
The filter accepts the parameters: @var{struct_el}:@var{nb_iterations}, |
|
with the same syntax and semantics as the @ref{dilate} filter. |
|
|
|
@subsection smooth |
|
|
|
Smooth the input video. |
|
|
|
The filter takes the following parameters: |
|
@var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}. |
|
|
|
@var{type} is the type of smooth filter to apply, and can be one of |
|
the following values: "blur", "blur_no_scale", "median", "gaussian", |
|
"bilateral". The default value is "gaussian". |
|
|
|
@var{param1}, @var{param2}, @var{param3}, and @var{param4} are |
|
parameters whose meanings depend on smooth type. @var{param1} and |
|
@var{param2} accept integer positive values or 0, @var{param3} and |
|
@var{param4} accept float values. |
|
|
|
The default value for @var{param1} is 3, the default value for the |
|
other parameters is 0. |
|
|
|
These parameters correspond to the parameters assigned to the |
|
libopencv function @code{cvSmooth}. |
|
|
|
@anchor{overlay} |
|
@section overlay |
|
|
|
Overlay one video on top of another. |
|
|
|
It takes two inputs and one output, the first input is the "main" |
|
video on which the second input is overlayed. |
|
|
|
It accepts the parameters: @var{x}:@var{y}[:@var{options}]. |
|
|
|
@var{x} is the x coordinate of the overlayed video on the main video, |
|
@var{y} is the y coordinate. @var{x} and @var{y} are expressions containing |
|
the following parameters: |
|
|
|
@table @option |
|
@item main_w, main_h |
|
main input width and height |
|
|
|
@item W, H |
|
same as @var{main_w} and @var{main_h} |
|
|
|
@item overlay_w, overlay_h |
|
overlay input width and height |
|
|
|
@item w, h |
|
same as @var{overlay_w} and @var{overlay_h} |
|
@end table |
|
|
|
@var{options} is an optional list of @var{key}=@var{value} pairs, |
|
separated by ":". |
|
|
|
The description of the accepted options follows. |
|
|
|
@table @option |
|
@item rgb |
|
If set to 1, force the filter to accept inputs in the RGB |
|
color space. Default value is 0. |
|
@end table |
|
|
|
Be aware that frames are taken from each input video in timestamp |
|
order, hence, if their initial timestamps differ, it is a a good idea |
|
to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to |
|
have them begin in the same zero timestamp, as it does the example for |
|
the @var{movie} filter. |
|
|
|
Follow some examples: |
|
@example |
|
# draw the overlay at 10 pixels from the bottom right |
|
# corner of the main video. |
|
overlay=main_w-overlay_w-10:main_h-overlay_h-10 |
|
|
|
# insert a transparent PNG logo in the bottom left corner of the input |
|
movie=logo.png [logo]; |
|
[in][logo] overlay=10:main_h-overlay_h-10 [out] |
|
|
|
# insert 2 different transparent PNG logos (second logo on bottom |
|
# right corner): |
|
movie=logo1.png [logo1]; |
|
movie=logo2.png [logo2]; |
|
[in][logo1] overlay=10:H-h-10 [in+logo1]; |
|
[in+logo1][logo2] overlay=W-w-10:H-h-10 [out] |
|
|
|
# add a transparent color layer on top of the main video, |
|
# WxH specifies the size of the main input to the overlay filter |
|
color=red@.3:WxH [over]; [in][over] overlay [out] |
|
@end example |
|
|
|
You can chain together more overlays but the efficiency of such |
|
approach is yet to be tested. |
|
|
|
@section pad |
|
|
|
Add paddings to the input image, and places the original input at the |
|
given coordinates @var{x}, @var{y}. |
|
|
|
It accepts the following parameters: |
|
@var{width}:@var{height}:@var{x}:@var{y}:@var{color}. |
|
|
|
The parameters @var{width}, @var{height}, @var{x}, and @var{y} are |
|
expressions containing the following constants: |
|
|
|
@table @option |
|
@item in_w, in_h |
|
the input video width and height |
|
|
|
@item iw, ih |
|
same as @var{in_w} and @var{in_h} |
|
|
|
@item out_w, out_h |
|
the output width and height, that is the size of the padded area as |
|
specified by the @var{width} and @var{height} expressions |
|
|
|
@item ow, oh |
|
same as @var{out_w} and @var{out_h} |
|
|
|
@item x, y |
|
x and y offsets as specified by the @var{x} and @var{y} |
|
expressions, or NAN if not yet specified |
|
|
|
@item a |
|
same as @var{iw} / @var{ih} |
|
|
|
@item sar |
|
input sample aspect ratio |
|
|
|
@item dar |
|
input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar} |
|
|
|
@item hsub, vsub |
|
horizontal and vertical chroma subsample values. For example for the |
|
pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1. |
|
@end table |
|
|
|
Follows the description of the accepted parameters. |
|
|
|
@table @option |
|
@item width, height |
|
|
|
Specify the size of the output image with the paddings added. If the |
|
value for @var{width} or @var{height} is 0, the corresponding input size |
|
is used for the output. |
|
|
|
The @var{width} expression can reference the value set by the |
|
@var{height} expression, and vice versa. |
|
|
|
The default value of @var{width} and @var{height} is 0. |
|
|
|
@item x, y |
|
|
|
Specify the offsets where to place the input image in the padded area |
|
with respect to the top/left border of the output image. |
|
|
|
The @var{x} expression can reference the value set by the @var{y} |
|
expression, and vice versa. |
|
|
|
The default value of @var{x} and @var{y} is 0. |
|
|
|
@item color |
|
|
|
Specify the color of the padded area, it can be the name of a color |
|
(case insensitive match) or a 0xRRGGBB[AA] sequence. |
|
|
|
The default value of @var{color} is "black". |
|
|
|
@end table |
|
|
|
Some examples follow: |
|
|
|
@example |
|
# Add paddings with color "violet" to the input video. Output video |
|
# size is 640x480, the top-left corner of the input video is placed at |
|
# column 0, row 40. |
|
pad=640:480:0:40:violet |
|
|
|
# pad the input to get an output with dimensions increased bt 3/2, |
|
# and put the input video at the center of the padded area |
|
pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2" |
|
|
|
# pad the input to get a squared output with size equal to the maximum |
|
# value between the input width and height, and put the input video at |
|
# the center of the padded area |
|
pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2" |
|
|
|
# pad the input to get a final w/h ratio of 16:9 |
|
pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2" |
|
|
|
# for anamorphic video, in order to set the output display aspect ratio, |
|
# it is necessary to use sar in the expression, according to the relation: |
|
# (ih * X / ih) * sar = output_dar |
|
# X = output_dar / sar |
|
pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2" |
|
|
|
# double output size and put the input video in the bottom-right |
|
# corner of the output padded area |
|
pad="2*iw:2*ih:ow-iw:oh-ih" |
|
@end example |
|
|
|
@section pixdesctest |
|
|
|
Pixel format descriptor test filter, mainly useful for internal |
|
testing. The output video should be equal to the input video. |
|
|
|
For example: |
|
@example |
|
format=monow, pixdesctest |
|
@end example |
|
|
|
can be used to test the monowhite pixel format descriptor definition. |
|
|
|
@section scale |
|
|
|
Scale the input video to @var{width}:@var{height}[:@var{interl}=@{1|-1@}] and/or convert the image format. |
|
|
|
The scale filter forces the output display aspect ratio to be the same |
|
of the input, by changing the output sample aspect ratio. |
|
|
|
The parameters @var{width} and @var{height} are expressions containing |
|
the following constants: |
|
|
|
@table @option |
|
@item in_w, in_h |
|
the input width and height |
|
|
|
@item iw, ih |
|
same as @var{in_w} and @var{in_h} |
|
|
|
@item out_w, out_h |
|
the output (cropped) width and height |
|
|
|
@item ow, oh |
|
same as @var{out_w} and @var{out_h} |
|
|
|
@item a |
|
same as @var{iw} / @var{ih} |
|
|
|
@item sar |
|
input sample aspect ratio |
|
|
|
@item dar |
|
input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar} |
|
|
|
@item hsub, vsub |
|
horizontal and vertical chroma subsample values. For example for the |
|
pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1. |
|
@end table |
|
|
|
If the input image format is different from the format requested by |
|
the next filter, the scale filter will convert the input to the |
|
requested format. |
|
|
|
If the value for @var{width} or @var{height} is 0, the respective input |
|
size is used for the output. |
|
|
|
If the value for @var{width} or @var{height} is -1, the scale filter will |
|
use, for the respective output size, a value that maintains the aspect |
|
ratio of the input image. |
|
|
|
The default value of @var{width} and @var{height} is 0. |
|
|
|
Valid values for the optional parameter @var{interl} are: |
|
|
|
@table @option |
|
@item 1 |
|
force interlaced aware scaling |
|
|
|
@item -1 |
|
select interlaced aware scaling depending on whether the source frames |
|
are flagged as interlaced or not |
|
@end table |
|
|
|
Unless @var{interl} is set to one of the above options, interlaced scaling will not be used. |
|
|
|
Some examples follow: |
|
@example |
|
# scale the input video to a size of 200x100. |
|
scale=200:100 |
|
|
|
# scale the input to 2x |
|
scale=2*iw:2*ih |
|
# the above is the same as |
|
scale=2*in_w:2*in_h |
|
|
|
# scale the input to 2x with forced interlaced scaling |
|
scale=2*iw:2*ih:interl=1 |
|
|
|
# scale the input to half size |
|
scale=iw/2:ih/2 |
|
|
|
# increase the width, and set the height to the same size |
|
scale=3/2*iw:ow |
|
|
|
# seek for Greek harmony |
|
scale=iw:1/PHI*iw |
|
scale=ih*PHI:ih |
|
|
|
# increase the height, and set the width to 3/2 of the height |
|
scale=3/2*oh:3/5*ih |
|
|
|
# increase the size, but make the size a multiple of the chroma |
|
scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub" |
|
|
|
# increase the width to a maximum of 500 pixels, keep the same input aspect ratio |
|
scale='min(500\, iw*3/2):-1' |
|
@end example |
|
|
|
@section select |
|
Select frames to pass in output. |
|
|
|
It accepts in input an expression, which is evaluated for each input |
|
frame. If the expression is evaluated to a non-zero value, the frame |
|
is selected and passed to the output, otherwise it is discarded. |
|
|
|
The expression can contain the following constants: |
|
|
|
@table @option |
|
@item n |
|
the sequential number of the filtered frame, starting from 0 |
|
|
|
@item selected_n |
|
the sequential number of the selected frame, starting from 0 |
|
|
|
@item prev_selected_n |
|
the sequential number of the last selected frame, NAN if undefined |
|
|
|
@item TB |
|
timebase of the input timestamps |
|
|
|
@item pts |
|
the PTS (Presentation TimeStamp) of the filtered video frame, |
|
expressed in @var{TB} units, NAN if undefined |
|
|
|
@item t |
|
the PTS (Presentation TimeStamp) of the filtered video frame, |
|
expressed in seconds, NAN if undefined |
|
|
|
@item prev_pts |
|
the PTS of the previously filtered video frame, NAN if undefined |
|
|
|
@item prev_selected_pts |
|
the PTS of the last previously filtered video frame, NAN if undefined |
|
|
|
@item prev_selected_t |
|
the PTS of the last previously selected video frame, NAN if undefined |
|
|
|
@item start_pts |
|
the PTS of the first video frame in the video, NAN if undefined |
|
|
|
@item start_t |
|
the time of the first video frame in the video, NAN if undefined |
|
|
|
@item pict_type |
|
the type of the filtered frame, can assume one of the following |
|
values: |
|
@table @option |
|
@item I |
|
@item P |
|
@item B |
|
@item S |
|
@item SI |
|
@item SP |
|
@item BI |
|
@end table |
|
|
|
@item interlace_type |
|
the frame interlace type, can assume one of the following values: |
|
@table @option |
|
@item PROGRESSIVE |
|
the frame is progressive (not interlaced) |
|
@item TOPFIRST |
|
the frame is top-field-first |
|
@item BOTTOMFIRST |
|
the frame is bottom-field-first |
|
@end table |
|
|
|
@item key |
|
1 if the filtered frame is a key-frame, 0 otherwise |
|
|
|
@item pos |
|
the position in the file of the filtered frame, -1 if the information |
|
is not available (e.g. for synthetic video) |
|
@end table |
|
|
|
The default value of the select expression is "1". |
|
|
|
Some examples follow: |
|
|
|
@example |
|
# select all frames in input |
|
select |
|
|
|
# the above is the same as: |
|
select=1 |
|
|
|
# skip all frames: |
|
select=0 |
|
|
|
# select only I-frames |
|
select='eq(pict_type\,I)' |
|
|
|
# select one frame every 100 |
|
select='not(mod(n\,100))' |
|
|
|
# select only frames contained in the 10-20 time interval |
|
select='gte(t\,10)*lte(t\,20)' |
|
|
|
# select only I frames contained in the 10-20 time interval |
|
select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)' |
|
|
|
# select frames with a minimum distance of 10 seconds |
|
select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)' |
|
@end example |
|
|
|
@section setdar, setsar |
|
|
|
The @code{setdar} filter sets the Display Aspect Ratio for the filter |
|
output video. |
|
|
|
This is done by changing the specified Sample (aka Pixel) Aspect |
|
Ratio, according to the following equation: |
|
@example |
|
@var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR} |
|
@end example |
|
|
|
Keep in mind that the @code{setdar} filter does not modify the pixel |
|
dimensions of the video frame. Also the display aspect ratio set by |
|
this filter may be changed by later filters in the filterchain, |
|
e.g. in case of scaling or if another "setdar" or a "setsar" filter is |
|
applied. |
|
|
|
The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for |
|
the filter output video. |
|
|
|
Note that as a consequence of the application of this filter, the |
|
output display aspect ratio will change according to the equation |
|
above. |
|
|
|
Keep in mind that the sample aspect ratio set by the @code{setsar} |
|
filter may be changed by later filters in the filterchain, e.g. if |
|
another "setsar" or a "setdar" filter is applied. |
|
|
|
The @code{setdar} and @code{setsar} filters accept a parameter string |
|
which represents the wanted aspect ratio. The parameter can |
|
be a floating point number string, an expression, or a string of the form |
|
@var{num}:@var{den}, where @var{num} and @var{den} are the numerator |
|
and denominator of the aspect ratio. If the parameter is not |
|
specified, it is assumed the value "0:1". |
|
|
|
For example to change the display aspect ratio to 16:9, specify: |
|
@example |
|
setdar=16:9 |
|
@end example |
|
|
|
The example above is equivalent to: |
|
@example |
|
setdar=1.77777 |
|
@end example |
|
|
|
To change the sample aspect ratio to 10:11, specify: |
|
@example |
|
setsar=10:11 |
|
@end example |
|
|
|
@section setfield |
|
|
|
Force field for the output video frame. |
|
|
|
The @code{setfield} filter marks the interlace type field for the |
|
output frames. It does not change the input frame, but only sets the |
|
corresponding property, which affects how the frame is treated by |
|
followig filters (e.g. @code{fieldorder} or @code{yadif}). |
|
|
|
It accepts a parameter representing an integer or a string, which can |
|
assume the following values: |
|
@table @samp |
|
@item -1, auto |
|
Keep the same field property. |
|
|
|
@item 0, bff |
|
Mark the frame as bottom-field-first. |
|
|
|
@item 1, tff |
|
Mark the frame as top-field-first. |
|
@end table |
|
|
|
@section setpts |
|
|
|
Change the PTS (presentation timestamp) of the input video frames. |
|
|
|
Accept in input an expression evaluated through the eval API, which |
|
can contain the following constants: |
|
|
|
@table @option |
|
@item PTS |
|
the presentation timestamp in input |
|
|
|
@item N |
|
the count of the input frame, starting from 0. |
|
|
|
@item STARTPTS |
|
the PTS of the first video frame |
|
|
|
@item INTERLACED |
|
tell if the current frame is interlaced |
|
|
|
@item POS |
|
original position in the file of the frame, or undefined if undefined |
|
for the current frame |
|
|
|
@item PREV_INPTS |
|
previous input PTS |
|
|
|
@item PREV_OUTPTS |
|
previous output PTS |
|
|
|
@end table |
|
|
|
Some examples follow: |
|
|
|
@example |
|
# start counting PTS from zero |
|
setpts=PTS-STARTPTS |
|
|
|
# fast motion |
|
setpts=0.5*PTS |
|
|
|
# slow motion |
|
setpts=2.0*PTS |
|
|
|
# fixed rate 25 fps |
|
setpts=N/(25*TB) |
|
|
|
# fixed rate 25 fps with some jitter |
|
setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))' |
|
@end example |
|
|
|
@section settb |
|
|
|
Set the timebase to use for the output frames timestamps. |
|
It is mainly useful for testing timebase configuration. |
|
|
|
It accepts in input an arithmetic expression representing a rational. |
|
The expression can contain the constants "AVTB" (the |
|
default timebase), and "intb" (the input timebase). |
|
|
|
The default value for the input is "intb". |
|
|
|
Follow some examples. |
|
|
|
@example |
|
# set the timebase to 1/25 |
|
settb=1/25 |
|
|
|
# set the timebase to 1/10 |
|
settb=0.1 |
|
|
|
#set the timebase to 1001/1000 |
|
settb=1+0.001 |
|
|
|
#set the timebase to 2*intb |
|
settb=2*intb |
|
|
|
#set the default timebase value |
|
settb=AVTB |
|
@end example |
|
|
|
@section showinfo |
|
|
|
Show a line containing various information for each input video frame. |
|
The input video is not modified. |
|
|
|
The shown line contains a sequence of key/value pairs of the form |
|
@var{key}:@var{value}. |
|
|
|
A description of each shown parameter follows: |
|
|
|
@table @option |
|
@item n |
|
sequential number of the input frame, starting from 0 |
|
|
|
@item pts |
|
Presentation TimeStamp of the input frame, expressed as a number of |
|
time base units. The time base unit depends on the filter input pad. |
|
|
|
@item pts_time |
|
Presentation TimeStamp of the input frame, expressed as a number of |
|
seconds |
|
|
|
@item pos |
|
position of the frame in the input stream, -1 if this information in |
|
unavailable and/or meaningless (for example in case of synthetic video) |
|
|
|
@item fmt |
|
pixel format name |
|
|
|
@item sar |
|
sample aspect ratio of the input frame, expressed in the form |
|
@var{num}/@var{den} |
|
|
|
@item s |
|
size of the input frame, expressed in the form |
|
@var{width}x@var{height} |
|
|
|
@item i |
|
interlaced mode ("P" for "progressive", "T" for top field first, "B" |
|
for bottom field first) |
|
|
|
@item iskey |
|
1 if the frame is a key frame, 0 otherwise |
|
|
|
@item type |
|
picture type of the input frame ("I" for an I-frame, "P" for a |
|
P-frame, "B" for a B-frame, "?" for unknown type). |
|
Check also the documentation of the @code{AVPictureType} enum and of |
|
the @code{av_get_picture_type_char} function defined in |
|
@file{libavutil/avutil.h}. |
|
|
|
@item checksum |
|
Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame |
|
|
|
@item plane_checksum |
|
Adler-32 checksum (printed in hexadecimal) of each plane of the input frame, |
|
expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]" |
|
@end table |
|
|
|
@section slicify |
|
|
|
Pass the images of input video on to next video filter as multiple |
|
slices. |
|
|
|
@example |
|
ffmpeg -i in.avi -vf "slicify=32" out.avi |
|
@end example |
|
|
|
The filter accepts the slice height as parameter. If the parameter is |
|
not specified it will use the default value of 16. |
|
|
|
Adding this in the beginning of filter chains should make filtering |
|
faster due to better use of the memory cache. |
|
|
|
@section split |
|
|
|
Pass on the input video to two outputs. Both outputs are identical to |
|
the input video. |
|
|
|
For example: |
|
@example |
|
[in] split [splitout1][splitout2]; |
|
[splitout1] crop=100:100:0:0 [cropout]; |
|
[splitout2] pad=200:200:100:100 [padout]; |
|
@end example |
|
|
|
will create two separate outputs from the same input, one cropped and |
|
one padded. |
|
|
|
@section swapuv |
|
Swap U & V plane. |
|
|
|
@section thumbnail |
|
Select the most representative frame in a given sequence of consecutive frames. |
|
|
|
It accepts as argument the frames batch size to analyze (default @var{N}=100); |
|
in a set of @var{N} frames, the filter will pick one of them, and then handle |
|
the next batch of @var{N} frames until the end. |
|
|
|
Since the filter keeps track of the whole frames sequence, a bigger @var{N} |
|
value will result in a higher memory usage, so a high value is not recommended. |
|
|
|
The following example extract one picture each 50 frames: |
|
@example |
|
thumbnail=50 |
|
@end example |
|
|
|
Complete example of a thumbnail creation with @command{ffmpeg}: |
|
@example |
|
ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png |
|
@end example |
|
|
|
@section tile |
|
|
|
Tile several successive frames together. |
|
|
|
It accepts as argument the tile size (i.e. the number of lines and columns) |
|
in the form "@var{w}x@var{h}". |
|
|
|
For example, produce 8×8 PNG tiles of all keyframes (@option{-skip_frame |
|
nokey}) in a movie: |
|
@example |
|
ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png |
|
@end example |
|
The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from |
|
duplicating each output frame to accomodate the originally detected frame |
|
rate. |
|
|
|
@section tinterlace |
|
|
|
Perform various types of temporal field interlacing. |
|
|
|
Frames are counted starting from 1, so the first input frame is |
|
considered odd. |
|
|
|
This filter accepts a single parameter specifying the mode. Available |
|
modes are: |
|
|
|
@table @samp |
|
@item 0 |
|
Move odd frames into the upper field, even into the lower field, |
|
generating a double height frame at half framerate. |
|
|
|
@item 1 |
|
Only output even frames, odd frames are dropped, generating a frame with |
|
unchanged height at half framerate. |
|
|
|
@item 2 |
|
Only output odd frames, even frames are dropped, generating a frame with |
|
unchanged height at half framerate. |
|
|
|
@item 3 |
|
Expand each frame to full height, but pad alternate lines with black, |
|
generating a frame with double height at the same input framerate. |
|
|
|
@item 4 |
|
Interleave the upper field from odd frames with the lower field from |
|
even frames, generating a frame with unchanged height at half framerate. |
|
|
|
@item 5 |
|
Interleave the lower field from odd frames with the upper field from |
|
even frames, generating a frame with unchanged height at half framerate. |
|
@end table |
|
|
|
Default mode is 0. |
|
|
|
@section transpose |
|
|
|
Transpose rows with columns in the input video and optionally flip it. |
|
|
|
It accepts a parameter representing an integer, which can assume the |
|
values: |
|
|
|
@table @samp |
|
@item 0 |
|
Rotate by 90 degrees counterclockwise and vertically flip (default), that is: |
|
@example |
|
L.R L.l |
|
. . -> . . |
|
l.r R.r |
|
@end example |
|
|
|
@item 1 |
|
Rotate by 90 degrees clockwise, that is: |
|
@example |
|
L.R l.L |
|
. . -> . . |
|
l.r r.R |
|
@end example |
|
|
|
@item 2 |
|
Rotate by 90 degrees counterclockwise, that is: |
|
@example |
|
L.R R.r |
|
. . -> . . |
|
l.r L.l |
|
@end example |
|
|
|
@item 3 |
|
Rotate by 90 degrees clockwise and vertically flip, that is: |
|
@example |
|
L.R r.R |
|
. . -> . . |
|
l.r l.L |
|
@end example |
|
@end table |
|
|
|
@section unsharp |
|
|
|
Sharpen or blur the input video. |
|
|
|
It accepts the following parameters: |
|
@var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount} |
|
|
|
Negative values for the amount will blur the input video, while positive |
|
values will sharpen. All parameters are optional and default to the |
|
equivalent of the string '5:5:1.0:5:5:0.0'. |
|
|
|
@table @option |
|
|
|
@item luma_msize_x |
|
Set the luma matrix horizontal size. It can be an integer between 3 |
|
and 13, default value is 5. |
|
|
|
@item luma_msize_y |
|
Set the luma matrix vertical size. It can be an integer between 3 |
|
and 13, default value is 5. |
|
|
|
@item luma_amount |
|
Set the luma effect strength. It can be a float number between -2.0 |
|
and 5.0, default value is 1.0. |
|
|
|
@item chroma_msize_x |
|
Set the chroma matrix horizontal size. It can be an integer between 3 |
|
and 13, default value is 5. |
|
|
|
@item chroma_msize_y |
|
Set the chroma matrix vertical size. It can be an integer between 3 |
|
and 13, default value is 5. |
|
|
|
@item chroma_amount |
|
Set the chroma effect strength. It can be a float number between -2.0 |
|
and 5.0, default value is 0.0. |
|
|
|
@end table |
|
|
|
@example |
|
# Strong luma sharpen effect parameters |
|
unsharp=7:7:2.5 |
|
|
|
# Strong blur of both luma and chroma parameters |
|
unsharp=7:7:-2:7:7:-2 |
|
|
|
# Use the default values with @command{ffmpeg} |
|
ffmpeg -i in.avi -vf "unsharp" out.mp4 |
|
@end example |
|
|
|
@section vflip |
|
|
|
Flip the input video vertically. |
|
|
|
@example |
|
ffmpeg -i in.avi -vf "vflip" out.avi |
|
@end example |
|
|
|
@section yadif |
|
|
|
Deinterlace the input video ("yadif" means "yet another deinterlacing |
|
filter"). |
|
|
|
It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}. |
|
|
|
@var{mode} specifies the interlacing mode to adopt, accepts one of the |
|
following values: |
|
|
|
@table @option |
|
@item 0 |
|
output 1 frame for each frame |
|
@item 1 |
|
output 1 frame for each field |
|
@item 2 |
|
like 0 but skips spatial interlacing check |
|
@item 3 |
|
like 1 but skips spatial interlacing check |
|
@end table |
|
|
|
Default value is 0. |
|
|
|
@var{parity} specifies the picture field parity assumed for the input |
|
interlaced video, accepts one of the following values: |
|
|
|
@table @option |
|
@item 0 |
|
assume top field first |
|
@item 1 |
|
assume bottom field first |
|
@item -1 |
|
enable automatic detection |
|
@end table |
|
|
|
Default value is -1. |
|
If interlacing is unknown or decoder does not export this information, |
|
top field first will be assumed. |
|
|
|
@var{auto} specifies if deinterlacer should trust the interlaced flag |
|
and only deinterlace frames marked as interlaced |
|
|
|
@table @option |
|
@item 0 |
|
deinterlace all frames |
|
@item 1 |
|
only deinterlace frames marked as interlaced |
|
@end table |
|
|
|
Default value is 0. |
|
|
|
@c man end VIDEO FILTERS |
|
|
|
@chapter Video Sources |
|
@c man begin VIDEO SOURCES |
|
|
|
Below is a description of the currently available video sources. |
|
|
|
@section buffer |
|
|
|
Buffer video frames, and make them available to the filter chain. |
|
|
|
This source is mainly intended for a programmatic use, in particular |
|
through the interface defined in @file{libavfilter/vsrc_buffer.h}. |
|
|
|
It accepts the following parameters: |
|
@var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}:@var{sample_aspect_ratio_num}:@var{sample_aspect_ratio.den}:@var{scale_params} |
|
|
|
All the parameters but @var{scale_params} need to be explicitly |
|
defined. |
|
|
|
Follows the list of the accepted parameters. |
|
|
|
@table @option |
|
|
|
@item width, height |
|
Specify the width and height of the buffered video frames. |
|
|
|
@item pix_fmt_string |
|
A string representing the pixel format of the buffered video frames. |
|
It may be a number corresponding to a pixel format, or a pixel format |
|
name. |
|
|
|
@item timebase_num, timebase_den |
|
Specify numerator and denomitor of the timebase assumed by the |
|
timestamps of the buffered frames. |
|
|
|
@item sample_aspect_ratio.num, sample_aspect_ratio.den |
|
Specify numerator and denominator of the sample aspect ratio assumed |
|
by the video frames. |
|
|
|
@item scale_params |
|
Specify the optional parameters to be used for the scale filter which |
|
is automatically inserted when an input change is detected in the |
|
input size or format. |
|
@end table |
|
|
|
For example: |
|
@example |
|
buffer=320:240:yuv410p:1:24:1:1 |
|
@end example |
|
|
|
will instruct the source to accept video frames with size 320x240 and |
|
with format "yuv410p", assuming 1/24 as the timestamps timebase and |
|
square pixels (1:1 sample aspect ratio). |
|
Since the pixel format with name "yuv410p" corresponds to the number 6 |
|
(check the enum PixelFormat definition in @file{libavutil/pixfmt.h}), |
|
this example corresponds to: |
|
@example |
|
buffer=320:240:6:1:24:1:1 |
|
@end example |
|
|
|
@section cellauto |
|
|
|
Create a pattern generated by an elementary cellular automaton. |
|
|
|
The initial state of the cellular automaton can be defined through the |
|
@option{filename}, and @option{pattern} options. If such options are |
|
not specified an initial state is created randomly. |
|
|
|
At each new frame a new row in the video is filled with the result of |
|
the cellular automaton next generation. The behavior when the whole |
|
frame is filled is defined by the @option{scroll} option. |
|
|
|
This source accepts a list of options in the form of |
|
@var{key}=@var{value} pairs separated by ":". A description of the |
|
accepted options follows. |
|
|
|
@table @option |
|
@item filename, f |
|
Read the initial cellular automaton state, i.e. the starting row, from |
|
the specified file. |
|
In the file, each non-whitespace character is considered an alive |
|
cell, a newline will terminate the row, and further characters in the |
|
file will be ignored. |
|
|
|
@item pattern, p |
|
Read the initial cellular automaton state, i.e. the starting row, from |
|
the specified string. |
|
|
|
Each non-whitespace character in the string is considered an alive |
|
cell, a newline will terminate the row, and further characters in the |
|
string will be ignored. |
|
|
|
@item rate, r |
|
Set the video rate, that is the number of frames generated per second. |
|
Default is 25. |
|
|
|
@item random_fill_ratio, ratio |
|
Set the random fill ratio for the initial cellular automaton row. It |
|
is a floating point number value ranging from 0 to 1, defaults to |
|
1/PHI. |
|
|
|
This option is ignored when a file or a pattern is specified. |
|
|
|
@item random_seed, seed |
|
Set the seed for filling randomly the initial row, must be an integer |
|
included between 0 and UINT32_MAX. If not specified, or if explicitly |
|
set to -1, the filter will try to use a good random seed on a best |
|
effort basis. |
|
|
|
@item rule |
|
Set the cellular automaton rule, it is a number ranging from 0 to 255. |
|
Default value is 110. |
|
|
|
@item size, s |
|
Set the size of the output video. |
|
|
|
If @option{filename} or @option{pattern} is specified, the size is set |
|
by default to the width of the specified initial state row, and the |
|
height is set to @var{width} * PHI. |
|
|
|
If @option{size} is set, it must contain the width of the specified |
|
pattern string, and the specified pattern will be centered in the |
|
larger row. |
|
|
|
If a filename or a pattern string is not specified, the size value |
|
defaults to "320x518" (used for a randomly generated initial state). |
|
|
|
@item scroll |
|
If set to 1, scroll the output upward when all the rows in the output |
|
have been already filled. If set to 0, the new generated row will be |
|
written over the top row just after the bottom row is filled. |
|
Defaults to 1. |
|
|
|
@item start_full, full |
|
If set to 1, completely fill the output with generated rows before |
|
outputting the first frame. |
|
This is the default behavior, for disabling set the value to 0. |
|
|
|
@item stitch |
|
If set to 1, stitch the left and right row edges together. |
|
This is the default behavior, for disabling set the value to 0. |
|
@end table |
|
|
|
@subsection Examples |
|
|
|
@itemize |
|
@item |
|
Read the initial state from @file{pattern}, and specify an output of |
|
size 200x400. |
|
@example |
|
cellauto=f=pattern:s=200x400 |
|
@end example |
|
|
|
@item |
|
Generate a random initial row with a width of 200 cells, with a fill |
|
ratio of 2/3: |
|
@example |
|
cellauto=ratio=2/3:s=200x200 |
|
@end example |
|
|
|
@item |
|
Create a pattern generated by rule 18 starting by a single alive cell |
|
centered on an initial row with width 100: |
|
@example |
|
cellauto=p=@@:s=100x400:full=0:rule=18 |
|
@end example |
|
|
|
@item |
|
Specify a more elaborated initial pattern: |
|
@example |
|
cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18 |
|
@end example |
|
|
|
@end itemize |
|
|
|
@section color |
|
|
|
Provide an uniformly colored input. |
|
|
|
It accepts the following parameters: |
|
@var{color}:@var{frame_size}:@var{frame_rate} |
|
|
|
Follows the description of the accepted parameters. |
|
|
|
@table @option |
|
|
|
@item color |
|
Specify the color of the source. It can be the name of a color (case |
|
insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an |
|
alpha specifier. The default value is "black". |
|
|
|
@item frame_size |
|
Specify the size of the sourced video, it may be a string of the form |
|
@var{width}x@var{height}, or the name of a size abbreviation. The |
|
default value is "320x240". |
|
|
|
@item frame_rate |
|
Specify the frame rate of the sourced video, as the number of frames |
|
generated per second. It has to be a string in the format |
|
@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float |
|
number or a valid video frame rate abbreviation. The default value is |
|
"25". |
|
|
|
@end table |
|
|
|
For example the following graph description will generate a red source |
|
with an opacity of 0.2, with size "qcif" and a frame rate of 10 |
|
frames per second, which will be overlayed over the source connected |
|
to the pad with identifier "in". |
|
|
|
@example |
|
"color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]" |
|
@end example |
|
|
|
@section movie |
|
|
|
Read a video stream from a movie container. |
|
|
|
It accepts the syntax: @var{movie_name}[:@var{options}] where |
|
@var{movie_name} is the name of the resource to read (not necessarily |
|
a file but also a device or a stream accessed through some protocol), |
|
and @var{options} is an optional sequence of @var{key}=@var{value} |
|
pairs, separated by ":". |
|
|
|
The description of the accepted options follows. |
|
|
|
@table @option |
|
|
|
@item format_name, f |
|
Specifies the format assumed for the movie to read, and can be either |
|
the name of a container or an input device. If not specified the |
|
format is guessed from @var{movie_name} or by probing. |
|
|
|
@item seek_point, sp |
|
Specifies the seek point in seconds, the frames will be output |
|
starting from this seek point, the parameter is evaluated with |
|
@code{av_strtod} so the numerical value may be suffixed by an IS |
|
postfix. Default value is "0". |
|
|
|
@item stream_index, si |
|
Specifies the index of the video stream to read. If the value is -1, |
|
the best suited video stream will be automatically selected. Default |
|
value is "-1". |
|
|
|
@item loop |
|
Specifies how many times to read the video stream in sequence. |
|
If the value is less than 1, the stream will be read again and again. |
|
Default value is "1". |
|
|
|
Note that when the movie is looped the source timestamps are not |
|
changed, so it will generate non monotonically increasing timestamps. |
|
@end table |
|
|
|
This filter allows to overlay a second video on top of main input of |
|
a filtergraph as shown in this graph: |
|
@example |
|
input -----------> deltapts0 --> overlay --> output |
|
^ |
|
| |
|
movie --> scale--> deltapts1 -------+ |
|
@end example |
|
|
|
Some examples follow: |
|
@example |
|
# skip 3.2 seconds from the start of the avi file in.avi, and overlay it |
|
# on top of the input labelled as "in". |
|
movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie]; |
|
[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out] |
|
|
|
# read from a video4linux2 device, and overlay it on top of the input |
|
# labelled as "in" |
|
movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie]; |
|
[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out] |
|
|
|
@end example |
|
|
|
@section mptestsrc |
|
|
|
Generate various test patterns, as generated by the MPlayer test filter. |
|
|
|
The size of the generated video is fixed, and is 256x256. |
|
This source is useful in particular for testing encoding features. |
|
|
|
This source accepts an optional sequence of @var{key}=@var{value} pairs, |
|
separated by ":". The description of the accepted options follows. |
|
|
|
@table @option |
|
|
|
@item rate, r |
|
Specify the frame rate of the sourced video, as the number of frames |
|
generated per second. It has to be a string in the format |
|
@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float |
|
number or a valid video frame rate abbreviation. The default value is |
|
"25". |
|
|
|
@item duration, d |
|
Set the video duration of the sourced video. The accepted syntax is: |
|
@example |
|
[-]HH[:MM[:SS[.m...]]] |
|
[-]S+[.m...] |
|
@end example |
|
See also the function @code{av_parse_time()}. |
|
|
|
If not specified, or the expressed duration is negative, the video is |
|
supposed to be generated forever. |
|
|
|
@item test, t |
|
|
|
Set the number or the name of the test to perform. Supported tests are: |
|
@table @option |
|
@item dc_luma |
|
@item dc_chroma |
|
@item freq_luma |
|
@item freq_chroma |
|
@item amp_luma |
|
@item amp_chroma |
|
@item cbp |
|
@item mv |
|
@item ring1 |
|
@item ring2 |
|
@item all |
|
@end table |
|
|
|
Default value is "all", which will cycle through the list of all tests. |
|
@end table |
|
|
|
For example the following: |
|
@example |
|
testsrc=t=dc_luma |
|
@end example |
|
|
|
will generate a "dc_luma" test pattern. |
|
|
|
@section frei0r_src |
|
|
|
Provide a frei0r source. |
|
|
|
To enable compilation of this filter you need to install the frei0r |
|
header and configure FFmpeg with @code{--enable-frei0r}. |
|
|
|
The source supports the syntax: |
|
@example |
|
@var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}] |
|
@end example |
|
|
|
@var{size} is the size of the video to generate, may be a string of the |
|
form @var{width}x@var{height} or a frame size abbreviation. |
|
@var{rate} is the rate of the video to generate, may be a string of |
|
the form @var{num}/@var{den} or a frame rate abbreviation. |
|
@var{src_name} is the name to the frei0r source to load. For more |
|
information regarding frei0r and how to set the parameters read the |
|
section @ref{frei0r} in the description of the video filters. |
|
|
|
Some examples follow: |
|
@example |
|
# generate a frei0r partik0l source with size 200x200 and frame rate 10 |
|
# which is overlayed on the overlay filter main input |
|
frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay |
|
@end example |
|
|
|
@section life |
|
|
|
Generate a life pattern. |
|
|
|
This source is based on a generalization of John Conway's life game. |
|
|
|
The sourced input represents a life grid, each pixel represents a cell |
|
which can be in one of two possible states, alive or dead. Every cell |
|
interacts with its eight neighbours, which are the cells that are |
|
horizontally, vertically, or diagonally adjacent. |
|
|
|
At each interaction the grid evolves according to the adopted rule, |
|
which specifies the number of neighbor alive cells which will make a |
|
cell stay alive or born. The @option{rule} option allows to specify |
|
the rule to adopt. |
|
|
|
This source accepts a list of options in the form of |
|
@var{key}=@var{value} pairs separated by ":". A description of the |
|
accepted options follows. |
|
|
|
@table @option |
|
@item filename, f |
|
Set the file from which to read the initial grid state. In the file, |
|
each non-whitespace character is considered an alive cell, and newline |
|
is used to delimit the end of each row. |
|
|
|
If this option is not specified, the initial grid is generated |
|
randomly. |
|
|
|
@item rate, r |
|
Set the video rate, that is the number of frames generated per second. |
|
Default is 25. |
|
|
|
@item random_fill_ratio, ratio |
|
Set the random fill ratio for the initial random grid. It is a |
|
floating point number value ranging from 0 to 1, defaults to 1/PHI. |
|
It is ignored when a file is specified. |
|
|
|
@item random_seed, seed |
|
Set the seed for filling the initial random grid, must be an integer |
|
included between 0 and UINT32_MAX. If not specified, or if explicitly |
|
set to -1, the filter will try to use a good random seed on a best |
|
effort basis. |
|
|
|
@item rule |
|
Set the life rule. |
|
|
|
A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}", |
|
where @var{NS} and @var{NB} are sequences of numbers in the range 0-8, |
|
@var{NS} specifies the number of alive neighbor cells which make a |
|
live cell stay alive, and @var{NB} the number of alive neighbor cells |
|
which make a dead cell to become alive (i.e. to "born"). |
|
"s" and "b" can be used in place of "S" and "B", respectively. |
|
|
|
Alternatively a rule can be specified by an 18-bits integer. The 9 |
|
high order bits are used to encode the next cell state if it is alive |
|
for each number of neighbor alive cells, the low order bits specify |
|
the rule for "borning" new cells. Higher order bits encode for an |
|
higher number of neighbor cells. |
|
For example the number 6153 = @code{(12<<9)+9} specifies a stay alive |
|
rule of 12 and a born rule of 9, which corresponds to "S23/B03". |
|
|
|
Default value is "S23/B3", which is the original Conway's game of life |
|
rule, and will keep a cell alive if it has 2 or 3 neighbor alive |
|
cells, and will born a new cell if there are three alive cells around |
|
a dead cell. |
|
|
|
@item size, s |
|
Set the size of the output video. |
|
|
|
If @option{filename} is specified, the size is set by default to the |
|
same size of the input file. If @option{size} is set, it must contain |
|
the size specified in the input file, and the initial grid defined in |
|
that file is centered in the larger resulting area. |
|
|
|
If a filename is not specified, the size value defaults to "320x240" |
|
(used for a randomly generated initial grid). |
|
|
|
@item stitch |
|
If set to 1, stitch the left and right grid edges together, and the |
|
top and bottom edges also. Defaults to 1. |
|
|
|
@item mold |
|
Set cell mold speed. If set, a dead cell will go from @option{death_color} to |
|
@option{mold_color} with a step of @option{mold}. @option{mold} can have a |
|
value from 0 to 255. |
|
|
|
@item life_color |
|
Set the color of living (or new born) cells. |
|
|
|
@item death_color |
|
Set the color of dead cells. If @option{mold} is set, this is the first color |
|
used to represent a dead cell. |
|
|
|
@item mold_color |
|
Set mold color, for definitely dead and moldy cells. |
|
@end table |
|
|
|
@subsection Examples |
|
|
|
@itemize |
|
@item |
|
Read a grid from @file{pattern}, and center it on a grid of size |
|
300x300 pixels: |
|
@example |
|
life=f=pattern:s=300x300 |
|
@end example |
|
|
|
@item |
|
Generate a random grid of size 200x200, with a fill ratio of 2/3: |
|
@example |
|
life=ratio=2/3:s=200x200 |
|
@end example |
|
|
|
@item |
|
Specify a custom rule for evolving a randomly generated grid: |
|
@example |
|
life=rule=S14/B34 |
|
@end example |
|
|
|
@item |
|
Full example with slow death effect (mold) using @command{ffplay}: |
|
@example |
|
ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16 |
|
@end example |
|
@end itemize |
|
|
|
@section nullsrc, rgbtestsrc, testsrc |
|
|
|
The @code{nullsrc} source returns unprocessed video frames. It is |
|
mainly useful to be employed in analysis / debugging tools, or as the |
|
source for filters which ignore the input data. |
|
|
|
The @code{rgbtestsrc} source generates an RGB test pattern useful for |
|
detecting RGB vs BGR issues. You should see a red, green and blue |
|
stripe from top to bottom. |
|
|
|
The @code{testsrc} source generates a test video pattern, showing a |
|
color pattern, a scrolling gradient and a timestamp. This is mainly |
|
intended for testing purposes. |
|
|
|
These sources accept an optional sequence of @var{key}=@var{value} pairs, |
|
separated by ":". The description of the accepted options follows. |
|
|
|
@table @option |
|
|
|
@item size, s |
|
Specify the size of the sourced video, it may be a string of the form |
|
@var{width}x@var{height}, or the name of a size abbreviation. The |
|
default value is "320x240". |
|
|
|
@item rate, r |
|
Specify the frame rate of the sourced video, as the number of frames |
|
generated per second. It has to be a string in the format |
|
@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float |
|
number or a valid video frame rate abbreviation. The default value is |
|
"25". |
|
|
|
@item sar |
|
Set the sample aspect ratio of the sourced video. |
|
|
|
@item duration, d |
|
Set the video duration of the sourced video. The accepted syntax is: |
|
@example |
|
[-]HH[:MM[:SS[.m...]]] |
|
[-]S+[.m...] |
|
@end example |
|
See also the function @code{av_parse_time()}. |
|
|
|
If not specified, or the expressed duration is negative, the video is |
|
supposed to be generated forever. |
|
|
|
@item decimals, n |
|
Set the number of decimals to show in the timestamp, only used in the |
|
@code{testsrc} source. |
|
|
|
The displayed timestamp value will correspond to the original |
|
timestamp value multiplied by the power of 10 of the specified |
|
value. Default value is 0. |
|
@end table |
|
|
|
For example the following: |
|
@example |
|
testsrc=duration=5.3:size=qcif:rate=10 |
|
@end example |
|
|
|
will generate a video with a duration of 5.3 seconds, with size |
|
176x144 and a frame rate of 10 frames per second. |
|
|
|
If the input content is to be ignored, @code{nullsrc} can be used. The |
|
following command generates noise in the luminance plane by employing |
|
the @code{mp=geq} filter: |
|
@example |
|
nullsrc=s=256x256, mp=geq=random(1)*255:128:128 |
|
@end example |
|
|
|
@c man end VIDEO SOURCES |
|
|
|
@chapter Video Sinks |
|
@c man begin VIDEO SINKS |
|
|
|
Below is a description of the currently available video sinks. |
|
|
|
@section buffersink |
|
|
|
Buffer video frames, and make them available to the end of the filter |
|
graph. |
|
|
|
This sink is mainly intended for a programmatic use, in particular |
|
through the interface defined in @file{libavfilter/buffersink.h}. |
|
|
|
It does not require a string parameter in input, but you need to |
|
specify a pointer to a list of supported pixel formats terminated by |
|
-1 in the opaque parameter provided to @code{avfilter_init_filter} |
|
when initializing this sink. |
|
|
|
@section nullsink |
|
|
|
Null video sink, do absolutely nothing with the input video. It is |
|
mainly useful as a template and to be employed in analysis / debugging |
|
tools. |
|
|
|
@c man end VIDEO SINKS
|
|
|