[FFmpeg-devel] [PATCH] avcodec/setts_bsf: allow to use input stream timebase too

[Paul B Mahol]

On Sun, Aug 22, 2021 at 2:48 PM Andreas Rheinhardt <
andreas.rheinhardt at outlook.com> wrote:

> Paul B Mahol:
> > Signed-off-by: Paul B Mahol <onemda at gmail.com>
> > ---
> >  doc/bitstream_filters.texi | 5 ++++-
> >  libavcodec/setts_bsf.c     | 5 ++++-
> >  2 files changed, 8 insertions(+), 2 deletions(-)
> >
> > diff --git a/doc/bitstream_filters.texi b/doc/bitstream_filters.texi
> > index 1900eb4352..b5a0be8ca2 100644
> > --- a/doc/bitstream_filters.texi
> > +++ b/doc/bitstream_filters.texi
> > @@ -777,8 +777,11 @@ The previous output DTS.
> >  @item PREV_OUTPTS
> >  The previous output PTS.
> >
> > + at item ITB
> > +The input timebase of stream packet belongs.
> > +
> >  @item TB
> > -The timebase of stream packet belongs.
> > +The output timebase of stream packet belongs.
> >
> >  @item SR
> >  The sample rate of stream packet belongs.
> > diff --git a/libavcodec/setts_bsf.c b/libavcodec/setts_bsf.c
> > index d604f91f71..965c999500 100644
> > --- a/libavcodec/setts_bsf.c
> > +++ b/libavcodec/setts_bsf.c
> > @@ -41,7 +41,8 @@ static const char *const var_names[] = {
> >      "DTS",         ///< original DTS in the file of the frame
> >      "STARTPTS",    ///< PTS at start of movie
> >      "STARTDTS",    ///< DTS at start of movie
> > -    "TB",          ///< timebase of the stream
> > +    "ITB",         ///< input timebase of the stream
> > +    "TB",          ///< output timebase of the stream
> >      "SR",          ///< sample rate of the stream
> >      "NOPTS",       ///< The AV_NOPTS_VALUE constant
> >      NULL
> > @@ -59,6 +60,7 @@ enum var_name {
> >      VAR_DTS,
> >      VAR_STARTPTS,
> >      VAR_STARTDTS,
> > +    VAR_ITB,
> >      VAR_TB,
> >      VAR_SR,
> >      VAR_NOPTS,
> > @@ -154,6 +156,7 @@ static int setts_filter(AVBSFContext *ctx, AVPacket
> *pkt)
> >      s->var_values[VAR_PREV_OUTDTS] = s->prev_outdts;
> >      s->var_values[VAR_STARTPTS]    = s->start_pts;
> >      s->var_values[VAR_STARTDTS]    = s->start_dts;
> > +    s->var_values[VAR_ITB]         = ctx->time_base_in.den  ?
> av_q2d(ctx->time_base_in)  : 0;
> >      s->var_values[VAR_TB]          = ctx->time_base_out.den ?
> av_q2d(ctx->time_base_out) : 0;
> >      s->var_values[VAR_SR]          = ctx->par_in->sample_rate;
> >
> >
> This is of no use: It is the user which sets the input timebase and it
> is the bsf which (in its init function) chooses the output timebase (the
> generic bsf code sets it equal to the input timebase and most (all?)
> filters don't change it). This filter does not change it, so input and
> output timebases are always equal.
>
> The bug in #9382 is really in ffmpeg.c, it can't be fixed in this bsf at
> all as it lacks the information about the muxing timebase.
>

Are you telling me that one field there is now useless?
Above Code is correct.


>
> - Andreas
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".
>