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yading@10: .\" ========================================================================
yading@10: .\"
yading@10: .IX Title "FFMPEG-RESAMPLER 1"
yading@10: .TH FFMPEG-RESAMPLER 1 "2013-04-21" " " " "
yading@10: .\" For nroff, turn off justification.  Always turn off hyphenation; it makes
yading@10: .\" way too many mistakes in technical documents.
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yading@10: .nh
yading@10: .SH "NAME"
yading@10: ffmpeg\-resampler \- FFmpeg Resampler
yading@10: .SH "DESCRIPTION"
yading@10: .IX Header "DESCRIPTION"
yading@10: The FFmpeg resampler provides an high-level interface to the
yading@10: libswresample library audio resampling utilities. In particular it
yading@10: allows to perform audio resampling, audio channel layout rematrixing,
yading@10: and convert audio format and packing layout.
yading@10: .SH "RESAMPLER OPTIONS"
yading@10: .IX Header "RESAMPLER OPTIONS"
yading@10: The audio resampler supports the following named options.
yading@10: .PP
yading@10: Options may be set by specifying \-\fIoption\fR \fIvalue\fR in the
yading@10: FFmpeg tools, \fIoption\fR=\fIvalue\fR for the aresample filter,
yading@10: by setting the value explicitly in the
yading@10: \&\f(CW\*(C`SwrContext\*(C'\fR options or using the \fIlibavutil/opt.h\fR \s-1API\s0 for
yading@10: programmatic use.
yading@10: .IP "\fBich, in_channel_count\fR" 4
yading@10: .IX Item "ich, in_channel_count"
yading@10: Set the number of input channels. Default value is 0. Setting this
yading@10: value is not mandatory if the corresponding channel layout
yading@10: \&\fBin_channel_layout\fR is set.
yading@10: .IP "\fBoch, out_channel_count\fR" 4
yading@10: .IX Item "och, out_channel_count"
yading@10: Set the number of output channels. Default value is 0. Setting this
yading@10: value is not mandatory if the corresponding channel layout
yading@10: \&\fBout_channel_layout\fR is set.
yading@10: .IP "\fBuch, used_channel_count\fR" 4
yading@10: .IX Item "uch, used_channel_count"
yading@10: Set the number of used input channels. Default value is 0. This option is
yading@10: only used for special remapping.
yading@10: .IP "\fBisr, in_sample_rate\fR" 4
yading@10: .IX Item "isr, in_sample_rate"
yading@10: Set the input sample rate. Default value is 0.
yading@10: .IP "\fBosr, out_sample_rate\fR" 4
yading@10: .IX Item "osr, out_sample_rate"
yading@10: Set the output sample rate. Default value is 0.
yading@10: .IP "\fBisf, in_sample_fmt\fR" 4
yading@10: .IX Item "isf, in_sample_fmt"
yading@10: Specify the input sample format. It is set by default to \f(CW\*(C`none\*(C'\fR.
yading@10: .IP "\fBosf, out_sample_fmt\fR" 4
yading@10: .IX Item "osf, out_sample_fmt"
yading@10: Specify the output sample format. It is set by default to \f(CW\*(C`none\*(C'\fR.
yading@10: .IP "\fBtsf, internal_sample_fmt\fR" 4
yading@10: .IX Item "tsf, internal_sample_fmt"
yading@10: Set the internal sample format. Default value is \f(CW\*(C`none\*(C'\fR.
yading@10: This will automatically be chosen when it is not explicitly set.
yading@10: .IP "\fBicl, in_channel_layout\fR" 4
yading@10: .IX Item "icl, in_channel_layout"
yading@10: Set the input channel layout.
yading@10: .IP "\fBocl, out_channel_layout\fR" 4
yading@10: .IX Item "ocl, out_channel_layout"
yading@10: Set the output channel layout.
yading@10: .IP "\fBclev, center_mix_level\fR" 4
yading@10: .IX Item "clev, center_mix_level"
yading@10: Set the center mix level. It is a value expressed in deciBel, and must be
yading@10: in the interval [\-32,32].
yading@10: .IP "\fBslev, surround_mix_level\fR" 4
yading@10: .IX Item "slev, surround_mix_level"
yading@10: Set the surround mix level. It is a value expressed in deciBel, and must
yading@10: be in the interval [\-32,32].
yading@10: .IP "\fBlfe_mix_level\fR" 4
yading@10: .IX Item "lfe_mix_level"
yading@10: Set \s-1LFE\s0 mix into non \s-1LFE\s0 level. It is used when there is a \s-1LFE\s0 input but no
yading@10: \&\s-1LFE\s0 output. It is a value expressed in deciBel, and must
yading@10: be in the interval [\-32,32].
yading@10: .IP "\fBrmvol, rematrix_volume\fR" 4
yading@10: .IX Item "rmvol, rematrix_volume"
yading@10: Set rematrix volume. Default value is 1.0.
yading@10: .IP "\fBflags, swr_flags\fR" 4
yading@10: .IX Item "flags, swr_flags"
yading@10: Set flags used by the converter. Default value is 0.
yading@10: .Sp
yading@10: It supports the following individual flags:
yading@10: .RS 4
yading@10: .IP "\fBres\fR" 4
yading@10: .IX Item "res"
yading@10: force resampling, this flag forces resampling to be used even when the
yading@10: input and output sample rates match.
yading@10: .RE
yading@10: .RS 4
yading@10: .RE
yading@10: .IP "\fBdither_scale\fR" 4
yading@10: .IX Item "dither_scale"
yading@10: Set the dither scale. Default value is 1.
yading@10: .IP "\fBdither_method\fR" 4
yading@10: .IX Item "dither_method"
yading@10: Set dither method. Default value is 0.
yading@10: .Sp
yading@10: Supported values:
yading@10: .RS 4
yading@10: .IP "\fBrectangular\fR" 4
yading@10: .IX Item "rectangular"
yading@10: select rectangular dither
yading@10: .IP "\fBtriangular\fR" 4
yading@10: .IX Item "triangular"
yading@10: select triangular dither
yading@10: .IP "\fBtriangular_hp\fR" 4
yading@10: .IX Item "triangular_hp"
yading@10: select triangular dither with high pass
yading@10: .IP "\fBlipshitz\fR" 4
yading@10: .IX Item "lipshitz"
yading@10: select lipshitz noise shaping dither
yading@10: .IP "\fBshibata\fR" 4
yading@10: .IX Item "shibata"
yading@10: select shibata noise shaping dither
yading@10: .IP "\fBlow_shibata\fR" 4
yading@10: .IX Item "low_shibata"
yading@10: select low shibata noise shaping dither
yading@10: .IP "\fBhigh_shibata\fR" 4
yading@10: .IX Item "high_shibata"
yading@10: select high shibata noise shaping dither
yading@10: .IP "\fBf_weighted\fR" 4
yading@10: .IX Item "f_weighted"
yading@10: select f\-weighted noise shaping dither
yading@10: .IP "\fBmodified_e_weighted\fR" 4
yading@10: .IX Item "modified_e_weighted"
yading@10: select modified-e-weighted noise shaping dither
yading@10: .IP "\fBimproved_e_weighted\fR" 4
yading@10: .IX Item "improved_e_weighted"
yading@10: select improved-e-weighted noise shaping dither
yading@10: .RE
yading@10: .RS 4
yading@10: .RE
yading@10: .IP "\fBresampler\fR" 4
yading@10: .IX Item "resampler"
yading@10: Set resampling engine. Default value is swr.
yading@10: .Sp
yading@10: Supported values:
yading@10: .RS 4
yading@10: .IP "\fBswr\fR" 4
yading@10: .IX Item "swr"
yading@10: select the native \s-1SW\s0 Resampler; filter options precision and cheby are not
yading@10: applicable in this case.
yading@10: .IP "\fBsoxr\fR" 4
yading@10: .IX Item "soxr"
yading@10: select the SoX Resampler (where available); compensation, and filter options
yading@10: filter_size, phase_shift, filter_type & kaiser_beta, are not applicable in this
yading@10: case.
yading@10: .RE
yading@10: .RS 4
yading@10: .RE
yading@10: .IP "\fBfilter_size\fR" 4
yading@10: .IX Item "filter_size"
yading@10: For swr only, set resampling filter size, default value is 32.
yading@10: .IP "\fBphase_shift\fR" 4
yading@10: .IX Item "phase_shift"
yading@10: For swr only, set resampling phase shift, default value is 10, and must be in
yading@10: the interval [0,30].
yading@10: .IP "\fBlinear_interp\fR" 4
yading@10: .IX Item "linear_interp"
yading@10: Use Linear Interpolation if set to 1, default value is 0.
yading@10: .IP "\fBcutoff\fR" 4
yading@10: .IX Item "cutoff"
yading@10: Set cutoff frequency (swr: 6dB point; soxr: 0dB point) ratio; must be a float
yading@10: value between 0 and 1.  Default value is 0.97 with swr, and 0.91 with soxr
yading@10: (which, with a sample-rate of 44100, preserves the entire audio band to 20kHz).
yading@10: .IP "\fBprecision\fR" 4
yading@10: .IX Item "precision"
yading@10: For soxr only, the precision in bits to which the resampled signal will be
yading@10: calculated.  The default value of 20 (which, with suitable dithering, is
yading@10: appropriate for a destination bit-depth of 16) gives SoX's 'High Quality'; a
yading@10: value of 28 gives SoX's 'Very High Quality'.
yading@10: .IP "\fBcheby\fR" 4
yading@10: .IX Item "cheby"
yading@10: For soxr only, selects passband rolloff none (Chebyshev) & higher-precision
yading@10: approximation for 'irrational' ratios. Default value is 0.
yading@10: .IP "\fBasync\fR" 4
yading@10: .IX Item "async"
yading@10: For swr only, simple 1 parameter audio sync to timestamps using stretching,
yading@10: squeezing, filling and trimming. Setting this to 1 will enable filling and
yading@10: trimming, larger values represent the maximum amount in samples that the data
yading@10: may be stretched or squeezed for each second.
yading@10: Default value is 0, thus no compensation is applied to make the samples match
yading@10: the audio timestamps.
yading@10: .IP "\fBfirst_pts\fR" 4
yading@10: .IX Item "first_pts"
yading@10: For swr only, assume the first pts should be this value. The time unit is 1 / sample rate.
yading@10: This allows for padding/trimming at the start of stream. By default, no
yading@10: assumption is made about the first frame's expected pts, so no padding or
yading@10: trimming is done. For example, this could be set to 0 to pad the beginning with
yading@10: silence if an audio stream starts after the video stream or to trim any samples
yading@10: with a negative pts due to encoder delay.
yading@10: .IP "\fBmin_comp\fR" 4
yading@10: .IX Item "min_comp"
yading@10: For swr only, set the minimum difference between timestamps and audio data (in
yading@10: seconds) to trigger stretching/squeezing/filling or trimming of the
yading@10: data to make it match the timestamps. The default is that
yading@10: stretching/squeezing/filling and trimming is disabled
yading@10: (\fBmin_comp\fR = \f(CW\*(C`FLT_MAX\*(C'\fR).
yading@10: .IP "\fBmin_hard_comp\fR" 4
yading@10: .IX Item "min_hard_comp"
yading@10: For swr only, set the minimum difference between timestamps and audio data (in
yading@10: seconds) to trigger adding/dropping samples to make it match the
yading@10: timestamps.  This option effectively is a threshold to select between
yading@10: hard (trim/fill) and soft (squeeze/stretch) compensation. Note that
yading@10: all compensation is by default disabled through \fBmin_comp\fR.
yading@10: The default is 0.1.
yading@10: .IP "\fBcomp_duration\fR" 4
yading@10: .IX Item "comp_duration"
yading@10: For swr only, set duration (in seconds) over which data is stretched/squeezed
yading@10: to make it match the timestamps. Must be a non-negative double float value,
yading@10: default value is 1.0.
yading@10: .IP "\fBmax_soft_comp\fR" 4
yading@10: .IX Item "max_soft_comp"
yading@10: For swr only, set maximum factor by which data is stretched/squeezed to make it
yading@10: match the timestamps. Must be a non-negative double float value, default value
yading@10: is 0.
yading@10: .IP "\fBmatrix_encoding\fR" 4
yading@10: .IX Item "matrix_encoding"
yading@10: Select matrixed stereo encoding.
yading@10: .Sp
yading@10: It accepts the following values:
yading@10: .RS 4
yading@10: .IP "\fBnone\fR" 4
yading@10: .IX Item "none"
yading@10: select none
yading@10: .IP "\fBdolby\fR" 4
yading@10: .IX Item "dolby"
yading@10: select Dolby
yading@10: .IP "\fBdplii\fR" 4
yading@10: .IX Item "dplii"
yading@10: select Dolby Pro Logic \s-1II\s0
yading@10: .RE
yading@10: .RS 4
yading@10: .Sp
yading@10: Default value is \f(CW\*(C`none\*(C'\fR.
yading@10: .RE
yading@10: .IP "\fBfilter_type\fR" 4
yading@10: .IX Item "filter_type"
yading@10: For swr only, select resampling filter type. This only affects resampling
yading@10: operations.
yading@10: .Sp
yading@10: It accepts the following values:
yading@10: .RS 4
yading@10: .IP "\fBcubic\fR" 4
yading@10: .IX Item "cubic"
yading@10: select cubic
yading@10: .IP "\fBblackman_nuttall\fR" 4
yading@10: .IX Item "blackman_nuttall"
yading@10: select Blackman Nuttall Windowed Sinc
yading@10: .IP "\fBkaiser\fR" 4
yading@10: .IX Item "kaiser"
yading@10: select Kaiser Windowed Sinc
yading@10: .RE
yading@10: .RS 4
yading@10: .RE
yading@10: .IP "\fBkaiser_beta\fR" 4
yading@10: .IX Item "kaiser_beta"
yading@10: For swr only, set Kaiser Window Beta value. Must be an integer in the
yading@10: interval [2,16], default value is 9.
yading@10: .SH "SEE ALSO"
yading@10: .IX Header "SEE ALSO"
yading@10: \&\fIffmpeg\fR\|(1), \fIffplay\fR\|(1), \fIffprobe\fR\|(1), \fIffserver\fR\|(1), \fIlibswresample\fR\|(3)
yading@10: .SH "AUTHORS"
yading@10: .IX Header "AUTHORS"
yading@10: The FFmpeg developers.
yading@10: .PP
yading@10: For details about the authorship, see the Git history of the project
yading@10: (git://source.ffmpeg.org/ffmpeg), e.g. by typing the command
yading@10: \&\fBgit log\fR in the FFmpeg source directory, or browsing the
yading@10: online repository at <\fBhttp://source.ffmpeg.org\fR>.
yading@10: .PP
yading@10: Maintainers for the specific components are listed in the file
yading@10: \&\fI\s-1MAINTAINERS\s0\fR in the source code tree.