mirror of https://github.com/FFmpeg/FFmpeg.git
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
238 lines
6.6 KiB
238 lines
6.6 KiB
\input texinfo @c -*- texinfo -*- |
|
|
|
@settitle FFmpeg Resampler Documentation |
|
@titlepage |
|
@center @titlefont{FFmpeg Resampler Documentation} |
|
@end titlepage |
|
|
|
@top |
|
|
|
@contents |
|
|
|
@chapter Description |
|
@c man begin DESCRIPTION |
|
|
|
The FFmpeg resampler provides an high-level interface to the |
|
libswresample library audio resampling utilities. In particular it |
|
allows to perform audio resampling, audio channel layout rematrixing, |
|
and convert audio format and packing layout. |
|
|
|
@c man end DESCRIPTION |
|
|
|
@chapter Resampler Options |
|
@c man begin RESAMPLER OPTIONS |
|
|
|
The audio resampler supports the following named options. |
|
|
|
Options may be set by specifying -@var{option} @var{value} in the |
|
FFmpeg tools, @var{option}=@var{value} for the aresample filter, |
|
by setting the value explicitly in the |
|
@code{SwrContext} options or using the @file{libavutil/opt.h} API for |
|
programmatic use. |
|
|
|
@table @option |
|
|
|
@item ich, in_channel_count |
|
Set the number of input channels. Default value is 0. Setting this |
|
value is not mandatory if the corresponding channel layout |
|
@option{in_channel_layout} is set. |
|
|
|
@item och, out_channel_count |
|
Set the number of output channels. Default value is 0. Setting this |
|
value is not mandatory if the corresponding channel layout |
|
@option{out_channel_layout} is set. |
|
|
|
@item uch, used_channel_count |
|
Set the number of used channels. Default value is 0. This option is |
|
only used for special remapping. |
|
|
|
@item isr, in_sample_rate |
|
Set the input sample rate. Default value is 0. |
|
|
|
@item osr, out_sample_rate |
|
Set the output sample rate. Default value is 0. |
|
|
|
@item isf, in_sample_fmt |
|
Specify the input sample format. It is set by default to @code{none}. |
|
|
|
@item osf, out_sample_fmt |
|
Specify the output sample format. It is set by default to @code{none}. |
|
|
|
@item tsf, internal_sample_fmt |
|
Set the internal sample format. Default value is @code{none}. |
|
|
|
@item icl, in_channel_layout |
|
Set the input channel layout. |
|
|
|
@item ocl, out_channel_layout |
|
Set the output channel layout. |
|
|
|
@item clev, center_mix_level |
|
Set center mix level. It is a value expressed in deciBel, and must be |
|
inclusively included between -32 and +32. |
|
|
|
@item slev, surround_mix_level |
|
Set surround mix level. It is a value expressed in deciBel, and must |
|
be inclusively included between -32 and +32. |
|
|
|
@item lfe_mix_evel |
|
Set LFE mix level. |
|
|
|
@item rmvol, rematrix_volume |
|
Set rematrix volume. Default value is 1.0. |
|
|
|
@item flags, swr_flags |
|
Set flags used by the converter. Default value is 0. |
|
|
|
It supports the following individual flags: |
|
@table @option |
|
@item res |
|
force resampling |
|
@end table |
|
|
|
@item dither_scale |
|
Set the dither scale. Default value is 1. |
|
|
|
@item dither_method |
|
Set dither method. Default value is 0. |
|
|
|
Supported values: |
|
@table @samp |
|
@item rectangular |
|
select rectangular dither |
|
@item triangular |
|
select triangular dither |
|
@item triangular_hp |
|
select triangular dither with high pass |
|
@end table |
|
|
|
@item resampler |
|
Set resampling engine. Default value is swr. |
|
|
|
Supported values: |
|
@table @samp |
|
@item swr |
|
select the native SW Resampler; filter options precision and cheby are not |
|
applicable in this case. |
|
@item soxr |
|
select the SoX Resampler (where available); compensation, and filter options |
|
filter_size, phase_shift, filter_type & kaiser_beta, are not applicable in this |
|
case. |
|
@end table |
|
|
|
@item filter_size |
|
For swr only, set resampling filter size, default value is 32. |
|
|
|
@item phase_shift |
|
For swr only, set resampling phase shift, default value is 10, must be included |
|
between 0 and 30. |
|
|
|
@item linear_interp |
|
Use Linear Interpolation if set to 1, default value is 0. |
|
|
|
@item cutoff |
|
Set cutoff frequency (swr: 6dB point; soxr: 0dB point) ratio; must be a float |
|
value between 0 and 1. Default value is 0.97 with swr, and 0.91 with soxr |
|
(which, with a sample-rate of 44100, preserves the entire audio band to 20kHz). |
|
|
|
@item precision |
|
For soxr only, the precision in bits to which the resampled signal will be |
|
calculated. The default value of 20 (which, with suitable dithering, is |
|
appropriate for a destination bit-depth of 16) gives SoX's 'High Quality'; a |
|
value of 28 gives SoX's 'Very High Quality'. |
|
|
|
@item cheby |
|
For soxr only, selects passband rolloff none (Chebyshev) & higher-precision |
|
approximation for 'irrational' ratios. Default value is 0. |
|
|
|
@item async |
|
For swr only, simple 1 parameter audio sync to timestamps using stretching, |
|
squeezing, filling and trimming. Setting this to 1 will enable filling and |
|
trimming, larger values represent the maximum amount in samples that the data |
|
may be stretched or squeezed for each second. |
|
Default value is 0, thus no compensation is applied to make the samples match |
|
the audio timestamps. |
|
|
|
@item min_comp |
|
For swr only, set the minimum difference between timestamps and audio data (in |
|
seconds) to trigger stretching/squeezing/filling or trimming of the |
|
data to make it match the timestamps. The default is that |
|
stretching/squeezing/filling and trimming is disabled |
|
(@option{min_comp} = @code{FLT_MAX}). |
|
|
|
@item min_hard_comp |
|
For swr only, set the minimum difference between timestamps and audio data (in |
|
seconds) to trigger adding/dropping samples to make it match the |
|
timestamps. This option effectively is a threshold to select between |
|
hard (trim/fill) and soft (squeeze/stretch) compensation. Note that |
|
all compensation is by default disabled through @option{min_comp}. |
|
The default is 0.1. |
|
|
|
@item comp_duration |
|
For swr only, set duration (in seconds) over which data is stretched/squeezed |
|
to make it match the timestamps. Must be a non-negative double float value, |
|
default value is 1.0. |
|
|
|
@item max_soft_comp |
|
For swr only, set maximum factor by which data is stretched/squeezed to make it |
|
match the timestamps. Must be a non-negative double float value, default value |
|
is 0. |
|
|
|
@item matrix_encoding |
|
Select matrixed stereo encoding. |
|
|
|
It accepts the following values: |
|
@table @samp |
|
@item none |
|
select none |
|
@item dolby |
|
select Dolby |
|
@item dplii |
|
select Dolby Pro Logic II |
|
@end table |
|
|
|
Default value is @code{none}. |
|
|
|
@item filter_type |
|
For swr only, select resampling filter type. This only affects resampling |
|
operations. |
|
|
|
It accepts the following values: |
|
@table @samp |
|
@item cubic |
|
select cubic |
|
@item blackman_nuttall |
|
select Blackman Nuttall Windowed Sinc |
|
@item kaiser |
|
select Kaiser Windowed Sinc |
|
@end table |
|
|
|
@item kaiser_beta |
|
For swr only, set Kaiser Window Beta value. Must be an integer included between |
|
2 and 16, default value is 9. |
|
|
|
@end table |
|
|
|
@c man end RESAMPLER OPTIONS |
|
|
|
@chapter See Also |
|
|
|
@ifhtml |
|
@url{ffmpeg.html,ffmpeg}, @url{ffplay.html,ffplay}, @url{ffprobe.html,ffprobe}, @url{ffserver.html,ffserver}, |
|
@url{libswresample.html,libswresample} |
|
@end ifhtml |
|
|
|
@ifnothtml |
|
ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), libswresample(3) |
|
@end ifnothtml |
|
|
|
@include authors.texi |
|
|
|
@ignore |
|
|
|
@setfilename ffmpeg-resampler |
|
@settitle FFmpeg Resampler |
|
|
|
@end ignore |
|
|
|
@bye
|
|
|