mirror of
https://git.videolan.org/git/ffmpeg.git
synced 2024-08-26 03:11:51 +02:00
239 lines
7.7 KiB
Plaintext
239 lines
7.7 KiB
Plaintext
@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 input 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}.
|
|
This will automatically be chosen when it is not explicitly set.
|
|
|
|
@item icl, in_channel_layout
|
|
@item ocl, out_channel_layout
|
|
Set the input/output channel layout.
|
|
|
|
See @ref{channel layout syntax,,the Channel Layout section in the ffmpeg-utils(1) manual,ffmpeg-utils}
|
|
for the required syntax.
|
|
|
|
@item clev, center_mix_level
|
|
Set the center mix level. It is a value expressed in deciBel, and must be
|
|
in the interval [-32,32].
|
|
|
|
@item slev, surround_mix_level
|
|
Set the surround mix level. It is a value expressed in deciBel, and must
|
|
be in the interval [-32,32].
|
|
|
|
@item lfe_mix_level
|
|
Set LFE mix into non LFE level. It is used when there is a LFE input but no
|
|
LFE output. It is a value expressed in deciBel, and must
|
|
be in the interval [-32,32].
|
|
|
|
@item rmvol, rematrix_volume
|
|
Set rematrix volume. Default value is 1.0.
|
|
|
|
@item rematrix_maxval
|
|
Set maximum output value for rematrixing.
|
|
This can be used to prevent clipping vs. preventing volume reduction.
|
|
A value of 1.0 prevents clipping.
|
|
|
|
@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, this flag forces resampling to be used even when the
|
|
input and output sample rates match.
|
|
@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
|
|
@item lipshitz
|
|
select Lipshitz noise shaping dither.
|
|
@item shibata
|
|
select Shibata noise shaping dither.
|
|
@item low_shibata
|
|
select low Shibata noise shaping dither.
|
|
@item high_shibata
|
|
select high Shibata noise shaping dither.
|
|
@item f_weighted
|
|
select f-weighted noise shaping dither
|
|
@item modified_e_weighted
|
|
select modified-e-weighted noise shaping dither
|
|
@item improved_e_weighted
|
|
select improved-e-weighted noise shaping dither
|
|
|
|
@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, exact_rational, 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, and must be in
|
|
the interval [0,30].
|
|
|
|
@item linear_interp
|
|
Use linear interpolation when enabled (the default). Disable it if you want
|
|
to preserve speed instead of quality when exact_rational fails.
|
|
|
|
@item exact_rational
|
|
For swr only, when enabled, try to use exact phase_count based on input and
|
|
output sample rate. However, if it is larger than @code{1 << phase_shift},
|
|
the phase_count will be @code{1 << phase_shift} as fallback. Default is enabled.
|
|
|
|
@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 first_pts
|
|
For swr only, assume the first pts should be this value. The time unit is 1 / sample rate.
|
|
This allows for padding/trimming at the start of stream. By default, no
|
|
assumption is made about the first frame's expected pts, so no padding or
|
|
trimming is done. For example, this could be set to 0 to pad the beginning with
|
|
silence if an audio stream starts after the video stream or to trim any samples
|
|
with a negative pts due to encoder delay.
|
|
|
|
@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 a double float value in the
|
|
interval [2,16], default value is 9.
|
|
|
|
@item output_sample_bits
|
|
For swr only, set number of used output sample bits for dithering. Must be an integer in the
|
|
interval [0,64], default value is 0, which means it's not used.
|
|
|
|
@end table
|
|
|
|
@c man end RESAMPLER OPTIONS
|