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2433 lines
68 KiB
2433 lines
68 KiB
@chapter Filtergraph description |
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@c man begin FILTERGRAPH DESCRIPTION |
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A filtergraph is a directed graph of connected filters. It can contain |
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cycles, and there can be multiple links between a pair of |
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filters. Each link has one input pad on one side connecting it to one |
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filter from which it takes its input, and one output pad on the other |
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side connecting it to the one filter accepting its output. |
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|
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Each filter in a filtergraph is an instance of a filter class |
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registered in the application, which defines the features and the |
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number of input and output pads of the filter. |
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A filter with no input pads is called a "source", a filter with no |
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output pads is called a "sink". |
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@anchor{Filtergraph syntax} |
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@section Filtergraph syntax |
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A filtergraph can be represented using a textual representation, which is |
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recognized by the @option{-filter}/@option{-vf} and @option{-filter_complex} |
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options in @command{avconv} and @option{-vf} in @command{avplay}, and by the |
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@code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} function defined in |
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@file{libavfilter/avfiltergraph.h}. |
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A filterchain consists of a sequence of connected filters, each one |
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connected to the previous one in the sequence. A filterchain is |
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represented by a list of ","-separated filter descriptions. |
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A filtergraph consists of a sequence of filterchains. A sequence of |
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filterchains is represented by a list of ";"-separated filterchain |
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descriptions. |
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A filter is represented by a string of the form: |
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[@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}] |
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@var{filter_name} is the name of the filter class of which the |
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described filter is an instance of, and has to be the name of one of |
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the filter classes registered in the program. |
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The name of the filter class is optionally followed by a string |
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"=@var{arguments}". |
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@var{arguments} is a string which contains the parameters used to |
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initialize the filter instance, and are described in the filter |
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descriptions below. |
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The list of arguments can be quoted using the character "'" as initial |
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and ending mark, and the character '\' for escaping the characters |
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within the quoted text; otherwise the argument string is considered |
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terminated when the next special character (belonging to the set |
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"[]=;,") is encountered. |
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The name and arguments of the filter are optionally preceded and |
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followed by a list of link labels. |
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A link label allows to name a link and associate it to a filter output |
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or input pad. The preceding labels @var{in_link_1} |
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... @var{in_link_N}, are associated to the filter input pads, |
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the following labels @var{out_link_1} ... @var{out_link_M}, are |
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associated to the output pads. |
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When two link labels with the same name are found in the |
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filtergraph, a link between the corresponding input and output pad is |
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created. |
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If an output pad is not labelled, it is linked by default to the first |
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unlabelled input pad of the next filter in the filterchain. |
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For example in the filterchain: |
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@example |
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nullsrc, split[L1], [L2]overlay, nullsink |
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@end example |
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the split filter instance has two output pads, and the overlay filter |
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instance two input pads. The first output pad of split is labelled |
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"L1", the first input pad of overlay is labelled "L2", and the second |
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output pad of split is linked to the second input pad of overlay, |
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which are both unlabelled. |
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|
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In a complete filterchain all the unlabelled filter input and output |
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pads must be connected. A filtergraph is considered valid if all the |
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filter input and output pads of all the filterchains are connected. |
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|
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Libavfilter will automatically insert scale filters where format |
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conversion is required. It is possible to specify swscale flags |
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for those automatically inserted scalers by prepending |
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@code{sws_flags=@var{flags};} |
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to the filtergraph description. |
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Follows a BNF description for the filtergraph syntax: |
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@example |
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@var{NAME} ::= sequence of alphanumeric characters and '_' |
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@var{LINKLABEL} ::= "[" @var{NAME} "]" |
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@var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}] |
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@var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted) |
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@var{FILTER} ::= [@var{LINKNAMES}] @var{NAME} ["=" @var{ARGUMENTS}] [@var{LINKNAMES}] |
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@var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}] |
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@var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}] |
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@end example |
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@c man end FILTERGRAPH DESCRIPTION |
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@chapter Audio Filters |
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@c man begin AUDIO FILTERS |
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When you configure your Libav build, you can disable any of the |
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existing filters using --disable-filters. |
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The configure output will show the audio filters included in your |
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build. |
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Below is a description of the currently available audio filters. |
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@section aformat |
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Convert the input audio to one of the specified formats. The framework will |
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negotiate the most appropriate format to minimize conversions. |
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The filter accepts the following named parameters: |
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@table @option |
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@item sample_fmts |
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A comma-separated list of requested sample formats. |
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@item sample_rates |
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A comma-separated list of requested sample rates. |
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@item channel_layouts |
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A comma-separated list of requested channel layouts. |
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@end table |
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If a parameter is omitted, all values are allowed. |
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For example to force the output to either unsigned 8-bit or signed 16-bit stereo: |
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@example |
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aformat=sample_fmts\=u8\,s16:channel_layouts\=stereo |
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@end example |
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@section amix |
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Mixes multiple audio inputs into a single output. |
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For example |
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@example |
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avconv -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT |
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@end example |
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will mix 3 input audio streams to a single output with the same duration as the |
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first input and a dropout transition time of 3 seconds. |
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The filter accepts the following named parameters: |
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@table @option |
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@item inputs |
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Number of inputs. If unspecified, it defaults to 2. |
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@item duration |
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How to determine the end-of-stream. |
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@table @option |
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@item longest |
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Duration of longest input. (default) |
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@item shortest |
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Duration of shortest input. |
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@item first |
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Duration of first input. |
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@end table |
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@item dropout_transition |
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Transition time, in seconds, for volume renormalization when an input |
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stream ends. The default value is 2 seconds. |
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@end table |
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@section anull |
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Pass the audio source unchanged to the output. |
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@section ashowinfo |
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Show a line containing various information for each input audio frame. |
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The input audio is not modified. |
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The shown line contains a sequence of key/value pairs of the form |
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@var{key}:@var{value}. |
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A description of each shown parameter follows: |
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@table @option |
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@item n |
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sequential number of the input frame, starting from 0 |
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@item pts |
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Presentation timestamp of the input frame, in time base units; the time base |
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depends on the filter input pad, and is usually 1/@var{sample_rate}. |
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@item pts_time |
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presentation timestamp of the input frame in seconds |
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@item fmt |
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sample format |
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@item chlayout |
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channel layout |
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@item rate |
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sample rate for the audio frame |
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@item nb_samples |
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number of samples (per channel) in the frame |
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@item checksum |
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Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio |
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the data is treated as if all the planes were concatenated. |
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@item plane_checksums |
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A list of Adler-32 checksums for each data plane. |
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@end table |
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@section asplit |
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Split input audio into several identical outputs. |
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The filter accepts a single parameter which specifies the number of outputs. If |
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unspecified, it defaults to 2. |
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For example |
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@example |
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avconv -i INPUT -filter_complex asplit=5 OUTPUT |
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@end example |
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will create 5 copies of the input audio. |
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@section asyncts |
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Synchronize audio data with timestamps by squeezing/stretching it and/or |
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dropping samples/adding silence when needed. |
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The filter accepts the following named parameters: |
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@table @option |
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@item compensate |
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Enable stretching/squeezing the data to make it match the timestamps. Disabled |
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by default. When disabled, time gaps are covered with silence. |
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@item min_delta |
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Minimum difference between timestamps and audio data (in seconds) to trigger |
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adding/dropping samples. Default value is 0.1. If you get non-perfect sync with |
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this filter, try setting this parameter to 0. |
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@item max_comp |
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Maximum compensation in samples per second. Relevant only with compensate=1. |
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Default value 500. |
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@item first_pts |
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Assume the first pts should be this value. |
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This allows for padding/trimming at the start of stream. By default, no |
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assumption is made about the first frame's expected pts, so no padding or |
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trimming is done. For example, this could be set to 0 to pad the beginning with |
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silence if an audio stream starts after the video stream. |
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@end table |
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@section channelsplit |
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Split each channel in input audio stream into a separate output stream. |
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This filter accepts the following named parameters: |
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@table @option |
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@item channel_layout |
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Channel layout of the input stream. Default is "stereo". |
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@end table |
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For example, assuming a stereo input MP3 file |
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@example |
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avconv -i in.mp3 -filter_complex channelsplit out.mkv |
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@end example |
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will create an output Matroska file with two audio streams, one containing only |
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the left channel and the other the right channel. |
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To split a 5.1 WAV file into per-channel files |
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@example |
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avconv -i in.wav -filter_complex |
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'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]' |
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-map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]' |
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front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]' |
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side_right.wav |
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@end example |
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@section channelmap |
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Remap input channels to new locations. |
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This filter accepts the following named parameters: |
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@table @option |
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@item channel_layout |
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Channel layout of the output stream. |
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@item map |
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Map channels from input to output. The argument is a comma-separated list of |
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mappings, each in the @code{@var{in_channel}-@var{out_channel}} or |
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@var{in_channel} form. @var{in_channel} can be either the name of the input |
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channel (e.g. FL for front left) or its index in the input channel layout. |
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@var{out_channel} is the name of the output channel or its index in the output |
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channel layout. If @var{out_channel} is not given then it is implicitly an |
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index, starting with zero and increasing by one for each mapping. |
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@end table |
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If no mapping is present, the filter will implicitly map input channels to |
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output channels preserving index. |
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For example, assuming a 5.1+downmix input MOV file |
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@example |
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avconv -i in.mov -filter 'channelmap=map=DL-FL\,DR-FR' out.wav |
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@end example |
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will create an output WAV file tagged as stereo from the downmix channels of |
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the input. |
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To fix a 5.1 WAV improperly encoded in AAC's native channel order |
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@example |
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avconv -i in.wav -filter 'channelmap=1\,2\,0\,5\,3\,4:channel_layout=5.1' out.wav |
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@end example |
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@section join |
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Join multiple input streams into one multi-channel stream. |
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The filter accepts the following named parameters: |
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@table @option |
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@item inputs |
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Number of input streams. Defaults to 2. |
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@item channel_layout |
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Desired output channel layout. Defaults to stereo. |
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@item map |
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Map channels from inputs to output. The argument is a comma-separated list of |
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mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}} |
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form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel} |
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can be either the name of the input channel (e.g. FL for front left) or its |
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index in the specified input stream. @var{out_channel} is the name of the output |
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channel. |
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@end table |
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The filter will attempt to guess the mappings when those are not specified |
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explicitly. It does so by first trying to find an unused matching input channel |
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and if that fails it picks the first unused input channel. |
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E.g. to join 3 inputs (with properly set channel layouts) |
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@example |
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avconv -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT |
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@end example |
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To build a 5.1 output from 6 single-channel streams: |
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@example |
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avconv -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex |
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'join=inputs=6:channel_layout=5.1:map=0.0-FL\,1.0-FR\,2.0-FC\,3.0-SL\,4.0-SR\,5.0-LFE' |
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out |
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@end example |
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@section resample |
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Convert the audio sample format, sample rate and channel layout. This filter is |
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not meant to be used directly, it is inserted automatically by libavfilter |
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whenever conversion is needed. Use the @var{aformat} filter to force a specific |
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conversion. |
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@section volume |
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Adjust the input audio volume. |
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The filter accepts the following named parameters: |
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@table @option |
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@item volume |
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Expresses how the audio volume will be increased or decreased. |
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Output values are clipped to the maximum value. |
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The output audio volume is given by the relation: |
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@example |
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@var{output_volume} = @var{volume} * @var{input_volume} |
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@end example |
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Default value for @var{volume} is 1.0. |
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@item precision |
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Mathematical precision. |
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This determines which input sample formats will be allowed, which affects the |
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precision of the volume scaling. |
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@table @option |
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@item fixed |
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8-bit fixed-point; limits input sample format to U8, S16, and S32. |
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@item float |
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32-bit floating-point; limits input sample format to FLT. (default) |
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@item double |
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64-bit floating-point; limits input sample format to DBL. |
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@end table |
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@end table |
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@subsection Examples |
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@itemize |
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@item |
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Halve the input audio volume: |
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@example |
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volume=volume=0.5 |
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volume=volume=1/2 |
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volume=volume=-6.0206dB |
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@end example |
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@item |
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Increase input audio power by 6 decibels using fixed-point precision: |
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@example |
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volume=volume=6dB:precision=fixed |
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@end example |
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@end itemize |
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@c man end AUDIO FILTERS |
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@chapter Audio Sources |
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@c man begin AUDIO SOURCES |
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Below is a description of the currently available audio sources. |
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|
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@section anullsrc |
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|
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Null audio source, never return audio frames. It is mainly useful as a |
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template and to be employed in analysis / debugging tools. |
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It accepts as optional parameter a string of the form |
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@var{sample_rate}:@var{channel_layout}. |
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@var{sample_rate} specify the sample rate, and defaults to 44100. |
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@var{channel_layout} specify the channel layout, and can be either an |
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integer or a string representing a channel layout. The default value |
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of @var{channel_layout} is 3, which corresponds to CH_LAYOUT_STEREO. |
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|
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Check the channel_layout_map definition in |
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@file{libavutil/channel_layout.c} for the mapping between strings and |
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channel layout values. |
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Follow some examples: |
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@example |
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# set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO. |
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anullsrc=48000:4 |
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# same as |
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anullsrc=48000:mono |
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@end example |
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@section abuffer |
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Buffer audio frames, and make them available to the filter chain. |
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This source is not intended to be part of user-supplied graph descriptions but |
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for insertion by calling programs through the interface defined in |
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@file{libavfilter/buffersrc.h}. |
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It accepts the following named parameters: |
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@table @option |
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@item time_base |
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Timebase which will be used for timestamps of submitted frames. It must be |
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either a floating-point number or in @var{numerator}/@var{denominator} form. |
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@item sample_rate |
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Audio sample rate. |
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@item sample_fmt |
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Name of the sample format, as returned by @code{av_get_sample_fmt_name()}. |
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@item channel_layout |
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Channel layout of the audio data, in the form that can be accepted by |
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@code{av_get_channel_layout()}. |
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@end table |
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All the parameters need to be explicitly defined. |
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@c man end AUDIO SOURCES |
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@chapter Audio Sinks |
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@c man begin AUDIO SINKS |
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Below is a description of the currently available audio sinks. |
|
|
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@section anullsink |
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|
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Null audio sink, do absolutely nothing with the input audio. It is |
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mainly useful as a template and to be employed in analysis / debugging |
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tools. |
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|
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@section abuffersink |
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This sink is intended for programmatic use. Frames that arrive on this sink can |
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be retrieved by the calling program using the interface defined in |
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@file{libavfilter/buffersink.h}. |
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This filter accepts no parameters. |
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|
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@c man end AUDIO SINKS |
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|
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@chapter Video Filters |
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@c man begin VIDEO FILTERS |
|
|
|
When you configure your Libav build, you can disable any of the |
|
existing filters using --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 blackframe |
|
|
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Detect frames that are (almost) completely black. Can be useful to |
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detect chapter transitions or commercials. Output lines consist of |
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the frame number of the detected frame, the percentage of blackness, |
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the position in the file if known or -1 and the timestamp in seconds. |
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|
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In order to display the output lines, you need to set the loglevel at |
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least to the AV_LOG_INFO value. |
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|
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The filter accepts the syntax: |
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@example |
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blackframe[=@var{amount}:[@var{threshold}]] |
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@end example |
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|
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@var{amount} is the percentage of the pixels that have to be below the |
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threshold, and defaults to 98. |
|
|
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@var{threshold} is the threshold below which a pixel value is |
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considered black, and defaults to 32. |
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|
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@section boxblur |
|
|
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Apply boxblur algorithm to the input video. |
|
|
|
This filter accepts the parameters: |
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@var{luma_power}:@var{luma_radius}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power} |
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|
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Chroma and alpha parameters are optional, if not specified they default |
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to the corresponding values set for @var{luma_radius} and |
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@var{luma_power}. |
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|
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@var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent |
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the radius in pixels of the box used for blurring the corresponding |
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input plane. They are expressions, and can contain the following |
|
constants: |
|
@table @option |
|
@item w, h |
|
the input width and height in pixels |
|
|
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@item cw, ch |
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the input chroma image width and height in pixels |
|
|
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@item hsub, vsub |
|
horizontal and vertical chroma subsample values. For example for the |
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pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1. |
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@end table |
|
|
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The radius must be a non-negative number, and must not be greater than |
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the value of the expression @code{min(w,h)/2} for the luma and alpha planes, |
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and of @code{min(cw,ch)/2} for the chroma planes. |
|
|
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@var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent |
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how many times the boxblur filter is applied to the corresponding |
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plane. |
|
|
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Some examples follow: |
|
|
|
@itemize |
|
|
|
@item |
|
Apply a boxblur filter with luma, chroma, and alpha radius |
|
set to 2: |
|
@example |
|
boxblur=2:1 |
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@end example |
|
|
|
@item |
|
Set luma radius to 2, alpha and chroma radius to 0 |
|
@example |
|
boxblur=2:1:0:0:0:0 |
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@end example |
|
|
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@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 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}. |
|
|
|
The parameters are expressions containing the following constants: |
|
|
|
@table @option |
|
@item E, PI, PHI |
|
the corresponding mathematical approximated values for e |
|
(euler number), pi (greek PI), PHI (golden ratio) |
|
|
|
@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 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 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 Libav 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 offsets where text will be drawn within the video frame. |
|
Relative to the top/left border of the output image. |
|
They accept expressions similar to the @ref{overlay} filter: |
|
@table @option |
|
|
|
@item x, y |
|
the computed values for @var{x} and @var{y}. They are evaluated for |
|
each new frame. |
|
|
|
@item main_w, main_h |
|
main input width and height |
|
|
|
@item W, H |
|
same as @var{main_w} and @var{main_h} |
|
|
|
@item text_w, text_h |
|
rendered text width and height |
|
|
|
@item w, h |
|
same as @var{text_w} and @var{text_h} |
|
|
|
@item n |
|
the number of frames processed, starting from 0 |
|
|
|
@item t |
|
timestamp expressed in seconds, NAN if the input timestamp is unknown |
|
|
|
@end table |
|
|
|
The default value of @var{x} and @var{y} is 0. |
|
|
|
@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 |
|
|
|
For example the command: |
|
@example |
|
drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'" |
|
@end example |
|
|
|
will draw "Test Text" with font FreeSerif, using the default values |
|
for the optional parameters. |
|
|
|
The command: |
|
@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 |
|
|
|
will 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%. |
|
|
|
Note that the double quotes are not necessary if spaces are not used |
|
within the parameter list. |
|
|
|
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{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. |
|
|
|
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 |
|
@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 |
|
./avconv -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 |
|
|
|
@section fps |
|
|
|
Convert the video to specified constant framerate by duplicating or dropping |
|
frames as necessary. |
|
|
|
This filter accepts the following named parameters: |
|
@table @option |
|
|
|
@item fps |
|
Desired output framerate. |
|
|
|
@end table |
|
|
|
@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 Libav with --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 colordepth. |
|
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{avconv}: |
|
@example |
|
avconv -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 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 @var{c0} (first pixel component) |
|
@item @var{c1} (second pixel component) |
|
@item @var{c2} (third pixel component) |
|
@item @var{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 @var{r} (red component) |
|
@item @var{g} (green component) |
|
@item @var{b} (blue component) |
|
@item @var{a} (alpha component) |
|
@end table |
|
|
|
The @var{lutyuv} filter requires YUV pixel formats in input, and |
|
accepts the options: |
|
@table @option |
|
@item @var{y} (Y/luminance component) |
|
@item @var{u} (U/Cb component) |
|
@item @var{v} (V/Cr component) |
|
@item @var{a} (alpha component) |
|
@end table |
|
|
|
The expressions can contain the following constants and functions: |
|
|
|
@table @option |
|
@item E, PI, PHI |
|
the corresponding mathematical approximated values for e |
|
(euler number), pi (greek PI), PHI (golden ratio) |
|
|
|
@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=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 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. |
|
|
|
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 Libav with --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{x} is the x coordinate of the overlayed video on the main video, |
|
@var{y} is the y coordinate. The parameters 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 |
|
|
|
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 |
|
avconv -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output |
|
|
|
# insert 2 different transparent PNG logos (second logo on bottom |
|
# right corner): |
|
avconv -i input -i logo1 -i logo2 -filter_complex |
|
'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output |
|
|
|
# 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 E, PI, PHI |
|
the corresponding mathematical approximated values for e |
|
(euler number), pi (greek PI), phi (golden ratio) |
|
|
|
@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 |
|
input display aspect ratio, same as @var{iw} / @var{ih} |
|
|
|
@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" |
|
|
|
# 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} and/or convert the image format. |
|
|
|
The parameters @var{width} and @var{height} are expressions containing |
|
the following constants: |
|
|
|
@table @option |
|
@item E, PI, PHI |
|
the corresponding mathematical approximated values for e |
|
(euler number), pi (greek PI), phi (golden ratio) |
|
|
|
@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 dar, a |
|
input display aspect ratio, same as @var{iw} / @var{ih} |
|
|
|
@item sar |
|
input sample aspect ratio |
|
|
|
@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. |
|
|
|
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 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 PI |
|
Greek PI |
|
|
|
@item PHI |
|
golden ratio |
|
|
|
@item E |
|
Euler number |
|
|
|
@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 |
|
|
|
@anchor{setdar} |
|
@section setdar |
|
|
|
Set 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: |
|
@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR} |
|
|
|
Keep in mind that this 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 filter accepts a parameter string which represents the wanted |
|
display aspect ratio. |
|
The parameter can be a floating point number string, or an expression |
|
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 |
|
# the above is equivalent to |
|
setdar=1.77777 |
|
@end example |
|
|
|
See also the @ref{setsar} filter documentation. |
|
|
|
@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 PI |
|
Greek PI |
|
|
|
@item PHI |
|
golden ratio |
|
|
|
@item E |
|
Euler number |
|
|
|
@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 |
|
|
|
@anchor{setsar} |
|
@section setsar |
|
|
|
Set 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 following |
|
equation: |
|
@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR} |
|
|
|
Keep in mind that the sample aspect ratio set by this filter may be |
|
changed by later filters in the filterchain, e.g. if another "setsar" |
|
or a "setdar" filter is applied. |
|
|
|
The filter accepts a parameter string which represents the wanted |
|
sample aspect ratio. |
|
The parameter can be a floating point number string, or an expression |
|
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 sample aspect ratio to 10:11, specify: |
|
@example |
|
setsar=10:11 |
|
@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 "PI", "E", "PHI", "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 of all the planes of the input frame |
|
|
|
@item plane_checksum |
|
Adler-32 checksum of each plane of the input frame, expressed in the form |
|
"[@var{c0} @var{c1} @var{c2} @var{c3}]" |
|
@end table |
|
|
|
@section split |
|
|
|
Split input video into several identical outputs. |
|
|
|
The filter accepts a single parameter which specifies the number of outputs. If |
|
unspecified, it defaults to 2. |
|
|
|
For example |
|
@example |
|
avconv -i INPUT -filter_complex split=5 OUTPUT |
|
@end example |
|
will create 5 copies of the input video. |
|
|
|
@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 luma_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{avconv} |
|
./avconv -i in.avi -vf "unsharp" out.mp4 |
|
@end example |
|
|
|
@section vflip |
|
|
|
Flip the input video vertically. |
|
|
|
@example |
|
./avconv -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} |
|
|
|
All the parameters 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. |
|
@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 AVPixelFormat definition in @file{libavutil/pixfmt.h}), |
|
this example corresponds to: |
|
@example |
|
buffer=320:240:6:1:24 |
|
@end example |
|
|
|
@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. |
|
|
|
Note that this source is a hack that bypasses the standard input path. It can be |
|
useful in applications that do not support arbitrary filter graphs, but its use |
|
is discouraged in those that do. Specifically in @command{avconv} this filter |
|
should never be used, the @option{-filter_complex} option fully replaces it. |
|
|
|
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". |
|
|
|
@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 nullsrc |
|
|
|
Null video source, never return images. It is mainly useful as a |
|
template and to be employed in analysis / debugging tools. |
|
|
|
It accepts as optional parameter a string of the form |
|
@var{width}:@var{height}:@var{timebase}. |
|
|
|
@var{width} and @var{height} specify the size of the configured |
|
source. The default values of @var{width} and @var{height} are |
|
respectively 352 and 288 (corresponding to the CIF size format). |
|
|
|
@var{timebase} specifies an arithmetic expression representing a |
|
timebase. The expression can contain the constants "PI", "E", "PHI", |
|
"AVTB" (the default timebase), and defaults to the value "AVTB". |
|
|
|
@section frei0r_src |
|
|
|
Provide a frei0r source. |
|
|
|
To enable compilation of this filter you need to install the frei0r |
|
header and configure Libav with --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 framerate 10 |
|
# which is overlayed on the overlay filter main input |
|
frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay |
|
@end example |
|
|
|
@section rgbtestsrc, testsrc |
|
|
|
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. |
|
|
|
Both 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 |
|
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. |
|
@end table |
|
|
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For example the following: |
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@example |
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testsrc=duration=5.3:size=qcif:rate=10 |
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@end example |
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will generate a video with a duration of 5.3 seconds, with size |
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176x144 and a framerate of 10 frames per second. |
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@c man end VIDEO SOURCES |
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@chapter Video Sinks |
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@c man begin VIDEO SINKS |
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Below is a description of the currently available video sinks. |
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@section buffersink |
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Buffer video frames, and make them available to the end of the filter |
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graph. |
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This sink is intended for a programmatic use through the interface defined in |
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@file{libavfilter/buffersink.h}. |
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@section nullsink |
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Null video sink, do absolutely nothing with the input video. It is |
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mainly useful as a template and to be employed in analysis / debugging |
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tools. |
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@c man end VIDEO SINKS
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