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

Gyan Doshi ffmpeg at gyani.pro
Thu Jun 9 21:06:04 EEST 2022


Plan to push in a day.

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}.
> - at item -vsync @var{parameter}
> -Video sync method.
> + at item -vsync @var{parameter} (@emph{global})
> + at 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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