[FFmpeg-devel] [PATCH v2] fftools/ffmpeg: accelerate seeking while reading input at native frame rate

[Linjie Fu]

On Wed, Jul 7, 2021 at 9:42 AM Linjie Fu <linjie.justin.fu at gmail.com> wrote:
>
> On Sun, Jul 4, 2021 at 10:50 PM Linjie Fu <fulinjie at zju.edu.cn> wrote:
> >
> > From: Linjie Fu <linjie.justin.fu at gmail.com>
> >
> > Skip the logic of frame rate emulation until the input reaches the
> > specified start time.
> >
> > Test CMD:
> >    $ffmpeg -re -ss 30 -i input.mp4 -pix_fmt yuv420p -f sdl2 -
> >
> > Before the patch:
> > first time to got frame, it takes 257305 us
> > After this patch:
> > first time to got frame, it takes 48879 us
> >
> > Signed-off-by: Linjie Fu <linjie.justin.fu at gmail.com>
> > ---
> > [v2]: fixed the mixed declaration and code warning
> > Calculate the time to get the first frame:
> > https://github.com/fulinjie/ffmpeg/commit/2aa4762e1e65709997b1ab9dd596332244db80ed
> >  fftools/ffmpeg.c | 8 ++++++--
> >  1 file changed, 6 insertions(+), 2 deletions(-)
> >
> > diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
> > index e97d879cb3..c8849e4250 100644
> > --- a/fftools/ffmpeg.c
> > +++ b/fftools/ffmpeg.c
> > @@ -4221,10 +4221,14 @@ static int get_input_packet(InputFile *f, AVPacket **pkt)
> >  {
> >      if (f->rate_emu) {
> >          int i;
> > +        int64_t pts;
> > +        int64_t now;
> >          for (i = 0; i < f->nb_streams; i++) {
> >              InputStream *ist = input_streams[f->ist_index + i];
> > -            int64_t pts = av_rescale(ist->dts, 1000000, AV_TIME_BASE);
> > -            int64_t now = av_gettime_relative() - ist->start;
> > +            if (!ist->got_output)
> > +                continue;
> > +            pts = av_rescale(ist->dts, 1000000, AV_TIME_BASE);
> > +            now = av_gettime_relative() - ist->start;
> >              if (pts > now)
> >                  return AVERROR(EAGAIN);
> >          }
> > --
> > 2.31.1
> ping, thx.
>
Another ping, thx.