Re: [FFmpeg-devel] [PATCH] ffmpeg: add option fps_mode

[Paul B Mahol <onemda@gmail.com>]

On Thu, Jun 9, 2022 at 8:06 PM Gyan Doshi <ffmpeg@gyani.pro> wrote:

> Plan to push in a day.
>

Is this a hack?

>
> On 2022-06-07 05:44 pm, Gyan Doshi wrote:
> > fps_mode sets video sync per output stream. Overrides vsync for matching
> > streams.
> > ---
> >   doc/ffmpeg.texi      |  8 +++++---
> >   fftools/ffmpeg.c     |  9 +++++----
> >   fftools/ffmpeg.h     |  3 +++
> >   fftools/ffmpeg_mux.c |  2 +-
> >   fftools/ffmpeg_opt.c | 41 ++++++++++++++++++++++++++++++-----------
> >   5 files changed, 44 insertions(+), 19 deletions(-)
> >
> > diff --git a/doc/ffmpeg.texi b/doc/ffmpeg.texi
> > index 0d7e1a479d..395ddc34ba 100644
> > --- a/doc/ffmpeg.texi
> > +++ b/doc/ffmpeg.texi
> > @@ -1618,10 +1618,12 @@ it may cause packet loss.
> >   It is useful for when flow speed of output packets is important, such
> as live streaming.
> >   @item -re (@emph{input})
> >   Read input at native frame rate. This is equivalent to setting
> @code{-readrate 1}.
> > -@item -vsync @var{parameter}
> > -Video sync method.
> > +@item -vsync @var{parameter} (@emph{global})
> > +@itemx -fps_mode[:@var{stream_specifier}] @var{parameter}
> (@emph{output,per-stream})
> > +Set video sync method / framerate mode. vsync is applied to all output
> video streams
> > +but can be overridden for a stream by setting fps_mode.
> >
> > -For compatibility reasons some of the values can be specified as
> numbers (shown
> > +For compatibility reasons some of the values for vsync can be specified
> as numbers (shown
> >   in parentheses in the following table). This is deprecated and will
> stop working
> >   in the future.
> >
> > diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
> > index 5ed287c522..2922a1e707 100644
> > --- a/fftools/ffmpeg.c
> > +++ b/fftools/ffmpeg.c
> > @@ -3018,11 +3018,12 @@ static int
> init_output_stream_encode(OutputStream *ost, AVFrame *frame)
> >
> >           if (!(enc_ctx->time_base.num && enc_ctx->time_base.den))
> >               enc_ctx->time_base =
> av_buffersink_get_time_base(ost->filter->filter);
> > -        if (   av_q2d(enc_ctx->time_base) < 0.001 && video_sync_method
> != VSYNC_PASSTHROUGH
> > -           && (video_sync_method == VSYNC_CFR || video_sync_method ==
> VSYNC_VSCFR ||
> > -               (video_sync_method == VSYNC_AUTO && !(of->format->flags
> & AVFMT_VARIABLE_FPS)))){
> > +        if (   av_q2d(enc_ctx->time_base) < 0.001 && ost->vsync_method
> != VSYNC_PASSTHROUGH
> > +           && (ost->vsync_method == VSYNC_CFR || ost->vsync_method ==
> VSYNC_VSCFR ||
> > +               (ost->vsync_method == VSYNC_AUTO && !(of->format->flags
> & AVFMT_VARIABLE_FPS)))){
> >               av_log(oc, AV_LOG_WARNING, "Frame rate very high for a
> muxer not efficiently supporting it.\n"
> > -                                       "Please consider specifying a
> lower framerate, a different muxer or -vsync 2\n");
> > +                                       "Please consider specifying a
> lower framerate, a different muxer or"
> > +                                       "setting vsync or fps_mode to
> vfr\n");
> >           }
> >
> >           enc_ctx->width  = av_buffersink_get_w(ost->filter->filter);
> > diff --git a/fftools/ffmpeg.h b/fftools/ffmpeg.h
> > index 7326193caf..69a368b8d1 100644
> > --- a/fftools/ffmpeg.h
> > +++ b/fftools/ffmpeg.h
> > @@ -176,6 +176,8 @@ typedef struct OptionsContext {
> >       int        nb_qscale;
> >       SpecifierOpt *forced_key_frames;
> >       int        nb_forced_key_frames;
> > +    SpecifierOpt *fps_mode;
> > +    int        nb_fps_mode;
> >       SpecifierOpt *force_fps;
> >       int        nb_force_fps;
> >       SpecifierOpt *frame_aspect_ratios;
> > @@ -489,6 +491,7 @@ typedef struct OutputStream {
> >       AVRational max_frame_rate;
> >       enum VideoSyncMethod vsync_method;
> >       int is_cfr;
> > +    const char *fps_mode;
> >       int force_fps;
> >       int top_field_first;
> >       int rotate_overridden;
> > diff --git a/fftools/ffmpeg_mux.c b/fftools/ffmpeg_mux.c
> > index 794d580635..a55fd18f8f 100644
> > --- a/fftools/ffmpeg_mux.c
> > +++ b/fftools/ffmpeg_mux.c
> > @@ -96,7 +96,7 @@ void of_write_packet(OutputFile *of, AVPacket *pkt,
> OutputStream *ost,
> >           return;
> >       }
> >
> > -    if ((st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO &&
> video_sync_method == VSYNC_DROP) ||
> > +    if ((st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO &&
> ost->vsync_method == VSYNC_DROP) ||
> >           (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO &&
> audio_sync_method < 0))
> >           pkt->pts = pkt->dts = AV_NOPTS_VALUE;
> >
> > diff --git a/fftools/ffmpeg_opt.c b/fftools/ffmpeg_opt.c
> > index 2c1b3bd0dd..0993985765 100644
> > --- a/fftools/ffmpeg_opt.c
> > +++ b/fftools/ffmpeg_opt.c
> > @@ -81,6 +81,7 @@ static const char *const opt_name_codec_tags[]
>         = {"tag", "atag",
> >   static const char *const opt_name_sample_fmts[]               =
> {"sample_fmt", NULL};
> >   static const char *const opt_name_qscale[]                    = {"q",
> "qscale", NULL};
> >   static const char *const opt_name_forced_key_frames[]         =
> {"forced_key_frames", NULL};
> > +static const char *const opt_name_fps_mode[]                  =
> {"fps_mode", NULL};
> >   static const char *const opt_name_force_fps[]                 =
> {"force_fps", NULL};
> >   static const char *const opt_name_frame_aspect_ratios[]       =
> {"aspect", NULL};
> >   static const char *const opt_name_rc_overrides[]              =
> {"rc_override", NULL};
> > @@ -265,6 +266,26 @@ static AVDictionary *strip_specifiers(AVDictionary
> *dict)
> >       return ret;
> >   }
> >
> > +static int parse_and_set_vsync(const char *arg, int *vsync_var, int
> file_idx, int st_idx, int is_global)
> > +{
> > +    if      (!av_strcasecmp(arg, "cfr"))         *vsync_var = VSYNC_CFR;
> > +    else if (!av_strcasecmp(arg, "vfr"))         *vsync_var = VSYNC_VFR;
> > +    else if (!av_strcasecmp(arg, "passthrough")) *vsync_var =
> VSYNC_PASSTHROUGH;
> > +    else if (!av_strcasecmp(arg, "drop"))        *vsync_var =
> VSYNC_DROP;
> > +    else if (!is_global && !av_strcasecmp(arg, "auto"))  *vsync_var =
> VSYNC_AUTO;
> > +    else if (!is_global) {
> > +        av_log(NULL, AV_LOG_FATAL, "Invalid value %s specified for
> fps_mode of #%d:%d.\n", arg, file_idx, st_idx);
> > +        exit_program(1);
> > +    }
> > +
> > +    if (is_global && *vsync_var == VSYNC_AUTO) {
> > +        video_sync_method = parse_number_or_die("vsync", arg, OPT_INT,
> VSYNC_AUTO, VSYNC_VFR);
> > +        av_log(NULL, AV_LOG_WARNING, "Passing a number to -vsync is
> deprecated,"
> > +               " use a string argument as described in the manual.\n");
> > +    }
> > +    return 0;
> > +}
> > +
> >   static int opt_filter_threads(void *optctx, const char *opt, const
> char *arg)
> >   {
> >       av_free(filter_nbthreads);
> > @@ -1905,6 +1926,10 @@ static OutputStream
> *new_video_stream(OptionsContext *o, AVFormatContext *oc, in
> >           MATCH_PER_STREAM_OPT(top_field_first, i, ost->top_field_first,
> oc, st);
> >
> >           ost->vsync_method = video_sync_method;
> > +        MATCH_PER_STREAM_OPT(fps_mode, str, ost->fps_mode, oc, st);
> > +        if (ost->fps_mode)
> > +            parse_and_set_vsync(ost->fps_mode, &ost->vsync_method,
> ost->file_index, ost->index, 0);
> > +
> >           if (ost->vsync_method == VSYNC_AUTO) {
> >               if (!strcmp(oc->oformat->name, "avi")) {
> >                   ost->vsync_method = VSYNC_VFR;
> > @@ -3248,16 +3273,7 @@ static int opt_audio_filters(void *optctx, const
> char *opt, const char *arg)
> >
> >   static int opt_vsync(void *optctx, const char *opt, const char *arg)
> >   {
> > -    if      (!av_strcasecmp(arg, "cfr"))         video_sync_method =
> VSYNC_CFR;
> > -    else if (!av_strcasecmp(arg, "vfr"))         video_sync_method =
> VSYNC_VFR;
> > -    else if (!av_strcasecmp(arg, "passthrough")) video_sync_method =
> VSYNC_PASSTHROUGH;
> > -    else if (!av_strcasecmp(arg, "drop"))        video_sync_method =
> VSYNC_DROP;
> > -
> > -    if (video_sync_method == VSYNC_AUTO) {
> > -        video_sync_method = parse_number_or_die("vsync", arg, OPT_INT,
> VSYNC_AUTO, VSYNC_VFR);
> > -        av_log(NULL, AV_LOG_WARNING, "Passing a number to -vsync is
> deprecated,"
> > -               " use a string argument as described in the manual.\n");
> > -    }
> > +    parse_and_set_vsync(arg, &video_sync_method, -1, -1, 1);
> >       return 0;
> >   }
> >
> > @@ -3620,7 +3636,7 @@ const OptionDef options[] = {
> >           "specify target file type (\"vcd\", \"svcd\", \"dvd\", \"dv\"
> or \"dv50\" "
> >           "with optional prefixes \"pal-\", \"ntsc-\" or \"film-\")",
> "type" },
> >       { "vsync",          HAS_ARG | OPT_EXPERT,                        {
> .func_arg = opt_vsync },
> > -        "video sync method", "" },
> > +        "set video sync method / fps_mode globally", "" },
> >       { "frame_drop_threshold", HAS_ARG | OPT_FLOAT | OPT_EXPERT,      {
> &frame_drop_threshold },
> >           "frame drop threshold", "" },
> >       { "async",          HAS_ARG | OPT_INT | OPT_EXPERT,              {
> &audio_sync_method },
> > @@ -3777,6 +3793,9 @@ const OptionDef options[] = {
> >           "force video tag/fourcc", "fourcc/tag" },
> >       { "qphist",       OPT_VIDEO | OPT_BOOL | OPT_EXPERT ,
>           { &qp_hist },
> >           "show QP histogram" },
> > +    { "fps_mode",     OPT_VIDEO | HAS_ARG | OPT_STRING | OPT_EXPERT |
> > +                      OPT_SPEC | OPT_OUTPUT,
>          { .off = OFFSET(fps_mode) },
> > +        "set framerate mode for matching video streams; overrides
> vsync." },
> >       { "force_fps",    OPT_VIDEO | OPT_BOOL | OPT_EXPERT  | OPT_SPEC |
> >                         OPT_OUTPUT,
>           { .off = OFFSET(force_fps) },
> >           "force the selected framerate, disable the best supported
> framerate selection" },
>
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