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avfilter/af_silenceremove: fix the any/all confusion and change default

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'any' stop mode is now correctly implemented for end trimming and is of limited usage.
Extend examples and other documentation of this filter.
This commit is contained in:
Paul B Mahol 2023-05-27 13:59:24 +02:00
parent 8d662adcc9
commit e8e4863325
3 changed files with 50 additions and 18 deletions
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62
doc/filters.texi
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@ -6419,15 +6419,16 @@ trimming. Default is 0, which is equal to trimming all samples detected
as silence.
@item start_mode
Specify mode of detection of silence end in start of multi-channel audio.
Specify mode of detection of silence end at start of multi-channel audio.
Can be @var{any} or @var{all}. Default is @var{any}.
With @var{any}, any sample that is detected as non-silence will cause
stopped trimming of silence.
With @var{all}, only if all channels are detected as non-silence will cause
stopped trimming of silence.
With @var{any}, any sample from any channel that is detected as non-silence
will trigger end of silence trimming at start of audio stream.
With @var{all}, only if every sample from every channel is detected as non-silence
will trigger end of silence trimming at start of audio stream, limited usage.
@item stop_periods
Set the count for trimming silence from the end of audio.
Set the count for trimming silence from the end of audio. When specifying a
positive value, it trims audio after it finds specified silence period.
To remove silence from the middle of a file, specify a @var{stop_periods}
that is negative. This value is then treated as a positive value and is
used to indicate the effect should restart processing as specified by
@ -6453,20 +6454,34 @@ trimming. Default is 0, which is equal to trimming all samples detected
as silence.
@item stop_mode
Specify mode of detection of silence start in end of multi-channel audio.
Can be @var{any} or @var{all}. Default is @var{any}.
With @var{any}, any sample that is detected as non-silence will cause
stopped trimming of silence.
With @var{all}, only if all channels are detected as non-silence will cause
stopped trimming of silence.
Specify mode of detection of silence start after start of multi-channel audio.
Can be @var{any} or @var{all}. Default is @var{all}.
With @var{any}, any sample from any channel that is detected as silence
will trigger start of silence trimming after start of audio stream, limited usage.
With @var{all}, only if every sample from every channel is detected as silence
will trigger start of silence trimming after start of audio stream.
@item detection
Set how is silence detected. Can be @code{avg}, @code{rms}, @code{median} or @code{peak}.
Set how is silence detected.
@table @option
@item avg
Mean of absolute values of samples in moving window.
@item rms
Root squared mean of absolute values of samples in moving window.
@item peak
Maximum of absolute values of samples in moving window.
@item median
Median of absolute values of samples in moving window.
@end table
Default value is @code{rms}.
@item window
Set duration in number of seconds used to calculate size of window in number
of samples for detecting silence.
of samples for detecting silence. Using @code{0} will effectively disable
any windowing and use only single sample per channel for silence detection.
In that case it may be needed to also set @option{start_silence} and/or
@option{stop_silence} to nonzero values with also @option{start_duration} and/or
@option{stop_duration} to nonzero values.
Default value is @code{0.02}. Allowed range is from @code{0} to @code{10}.
@end table
@ -6495,6 +6510,25 @@ silence is detected in all channels at same positions in stream:
@example
silenceremove=window=0:detection=peak:stop_mode=all:start_mode=all:stop_periods=-1:stop_threshold=0
@end example
@item
Trim every 2nd encountered silence period from beginning to end where there is
more than 1 second of silence per silence period in audio:
@example
silenceremove=stop_periods=-2:stop_duration=1:stop_threshold=-90dB
@end example
@item
Similar as above, but keep maximum of 0.5 seconds of silence from each trimmed period:
@example
silenceremove=stop_periods=-2:stop_duration=1:stop_threshold=-90dB:stop_silence=0.5
@end example
@item
Similar as above, but keep maximum of 1.5 seconds of silence from start of audio:
@example
silenceremove=stop_periods=-2:stop_duration=1:stop_threshold=-90dB:stop_silence=0.5:start_periods=1:start_duration=1:start_silence=1.5:stop_threshold=-90dB
@end example
@end itemize
@subsection Commands

2
libavfilter/af_silenceremove.c
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@ -129,7 +129,7 @@ static const AVOption silenceremove_options[] = {
{ "stop_duration", "set stop duration of silence part", OFFSET(stop_duration_opt), AV_OPT_TYPE_DURATION, {.i64=0}, 0, INT32_MAX, AF },
{ "stop_threshold", "set threshold for stop silence detection", OFFSET(stop_threshold), AV_OPT_TYPE_DOUBLE, {.dbl=0}, 0, DBL_MAX, AFR },
{ "stop_silence", "set stop duration of silence part to keep", OFFSET(stop_silence_opt), AV_OPT_TYPE_DURATION, {.i64=0}, 0, INT32_MAX, AF },
{ "stop_mode", "set which channel will trigger trimming from end", OFFSET(stop_mode), AV_OPT_TYPE_INT, {.i64=T_ANY}, T_ANY, T_ALL, AFR, "mode" },
{ "stop_mode", "set which channel will trigger trimming from end", OFFSET(stop_mode), AV_OPT_TYPE_INT, {.i64=T_ALL}, T_ANY, T_ALL, AFR, "mode" },
{ "detection", "set how silence is detected", OFFSET(detection), AV_OPT_TYPE_INT, {.i64=D_RMS}, 0, D_NB-1, AF, "detection" },
{ "avg", "use mean absolute values of samples", 0, AV_OPT_TYPE_CONST, {.i64=D_AVG}, 0, 0, AF, "detection" },
{ "rms", "use root mean squared values of samples", 0, AV_OPT_TYPE_CONST, {.i64=D_RMS}, 0, 0, AF, "detection" },

4
libavfilter/silenceremove_template.c
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@ -403,10 +403,8 @@ static void fn(filter_stop)(AVFilterContext *ctx,
s->stop_found_periods = 0;
if (s->stop_found_periods >= 0 || ctx->is_disabled) {
if (s->found_nonsilence) {
if (s->found_nonsilence)
s->stop_sample_count += stop_thres;
s->stop_sample_count *= stop_thres;
}
} else if (s->stop_silence_count > 0) {
const int dst_pos = out_nb_samples * nb_channels;
for (int ch = 0; ch < nb_channels; ch++)