[FFmpeg-devel] [PATCH] avfilter/af_apad: do not add infinte silence for zero pad_dur or whole_dur

[Marton Balint]

On Thu, 29 Jul 2021, Marton Balint wrote:

> Unfortunately pad_len and pad_dur behaviour was different if 0 was specified,
> pad_dur handled 0 duration as infinity, for pad_len, infinity was -1.
>
> Let's make the behaviour consistent by handling 0 duration for pad_dur and
> whole_dur as indeed 0 duration. This somewhat changes the behaviour of the
> filter if 0 was explicitly specified, but deprecating the old option and adding
> a new for the corrected behaviour seemed a bit overkill. So let's document the
> change instead.

Ping, anybody against this? Slightly breaks compatibility.

Thanks,
Marton

>
> Signed-off-by: Marton Balint <cus at passwd.hu>
> ---
> doc/filters.texi      | 7 +++++--
> libavfilter/af_apad.c | 8 ++++----
> libavfilter/version.h | 2 +-
> 3 files changed, 10 insertions(+), 7 deletions(-)
>
> diff --git a/doc/filters.texi b/doc/filters.texi
> index 66c0f87e47..f164f4d62d 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -2248,12 +2248,12 @@ with @option{pad_len}.
> @item pad_dur
> Specify the duration of samples of silence to add. See
> @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
> -for the accepted syntax. Used only if set to non-zero value.
> +for the accepted syntax. Used only if set to non-negative value.
>
> @item whole_dur
> Specify the minimum total duration in the output audio stream. See
> @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}
> -for the accepted syntax. Used only if set to non-zero value. If the value is longer than
> +for the accepted syntax. Used only if set to non-negative value. If the value is longer than
> the input audio length, silence is added to the end, until the value is reached.
> This option is mutually exclusive with @option{pad_dur}
> @end table
> @@ -2262,6 +2262,9 @@ If neither the @option{pad_len} nor the @option{whole_len} nor @option{pad_dur}
> nor @option{whole_dur} option is set, the filter will add silence to the end of
> the input stream indefinitely.
>
> +Note that for ffmpeg 4.4 and earlier a zero @option{pad_dur} or
> + at option{whole_dur} also caused the filter to add silence indefinitely.
> +
> @subsection Examples
>
> @itemize
> diff --git a/libavfilter/af_apad.c b/libavfilter/af_apad.c
> index 8628c0c2e2..ff60eaa397 100644
> --- a/libavfilter/af_apad.c
> +++ b/libavfilter/af_apad.c
> @@ -52,8 +52,8 @@ static const AVOption apad_options[] = {
>     { "packet_size", "set silence packet size",                                  OFFSET(packet_size), AV_OPT_TYPE_INT,   { .i64 = 4096 }, 0, INT_MAX, A },
>     { "pad_len",     "set number of samples of silence to add",                  OFFSET(pad_len),     AV_OPT_TYPE_INT64, { .i64 = -1 }, -1, INT64_MAX, A },
>     { "whole_len",   "set minimum target number of samples in the audio stream", OFFSET(whole_len),   AV_OPT_TYPE_INT64, { .i64 = -1 }, -1, INT64_MAX, A },
> -    { "pad_dur",     "set duration of silence to add",                           OFFSET(pad_dur),     AV_OPT_TYPE_DURATION, { .i64 = 0 }, 0, INT64_MAX, A },
> -    { "whole_dur",   "set minimum target duration in the audio stream",          OFFSET(whole_dur),   AV_OPT_TYPE_DURATION, { .i64 = 0 }, 0, INT64_MAX, A },
> +    { "pad_dur",     "set duration of silence to add",                           OFFSET(pad_dur),     AV_OPT_TYPE_DURATION, { .i64 = -1 }, -1, INT64_MAX, A },
> +    { "whole_dur",   "set minimum target duration in the audio stream",          OFFSET(whole_dur),   AV_OPT_TYPE_DURATION, { .i64 = -1 }, -1, INT64_MAX, A },
>     { NULL }
> };
>
> @@ -138,9 +138,9 @@ static int config_output(AVFilterLink *outlink)
>     AVFilterContext *ctx = outlink->src;
>     APadContext *s  = ctx->priv;
>
> -    if (s->pad_dur)
> +    if (s->pad_dur >= 0)
>         s->pad_len = av_rescale(s->pad_dur, outlink->sample_rate, AV_TIME_BASE);
> -    if (s->whole_dur)
> +    if (s->whole_dur >= 0)
>         s->whole_len = av_rescale(s->whole_dur, outlink->sample_rate, AV_TIME_BASE);
>
>     s->pad_len_left   = s->pad_len;
> diff --git a/libavfilter/version.h b/libavfilter/version.h
> index 75cd10dccd..85acd613a0 100644
> --- a/libavfilter/version.h
> +++ b/libavfilter/version.h
> @@ -31,7 +31,7 @@
>
> #define LIBAVFILTER_VERSION_MAJOR   8
> #define LIBAVFILTER_VERSION_MINOR   1
> -#define LIBAVFILTER_VERSION_MICRO 103
> +#define LIBAVFILTER_VERSION_MICRO 104
>
>
> #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
> -- 
> 2.26.2
>
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