[FFmpeg-devel] [PATCH] libavdevice/lavfi.c: adjust subcc_packet->pts to be in 90 timebase

[Chris Landry]

Haven't been able to connect to upload.ffmpeg.org.
Sample file is here:
https://www.dropbox.com/s/38ll6y7wws7zssr/cc_different_video_timebase.mp4?dl=0

Also have not been able to get the fate stuff working. I am not a C
developer and have a lot to learn here.


On Sat, Oct 1, 2016 at 6:27 AM, Michael Niedermayer <michael at niedermayer.cc>
wrote:

> On Fri, Sep 30, 2016 at 11:02:32PM -0400, Chris Landry wrote:
> > From: Chris Landry <topher.p.landry at gmail.com>
> >
> > When a video stream timebase is not 90k, the cc packet pts is relevant
> to the timebase of the video stream, but later is assumed to be 90k. Adjust
> it here to be 90k so timing is accurate in resulting subs.
> >
> > Signed-off-by: Chris Landry <topher.p.landry at gmail.com>
> > ---
> >  libavdevice/lavfi.c | 11 ++++++++++-
> >  1 file changed, 10 insertions(+), 1 deletion(-)
> >
> > diff --git a/libavdevice/lavfi.c b/libavdevice/lavfi.c
> > index f9b2694..ffe5e0e 100644
> > --- a/libavdevice/lavfi.c
> > +++ b/libavdevice/lavfi.c
> > @@ -58,6 +58,7 @@ typedef struct {
> >      AVFrame *decoded_frame;
> >      int nb_sinks;
> >      AVPacket subcc_packet;
> > +    AVRational video_time_base;
> >  } LavfiContext;
> >
> >  static int *create_all_formats(int n)
> > @@ -317,6 +318,8 @@ av_cold static int lavfi_read_header(AVFormatContext
> *avctx)
> >          st->codecpar->codec_type = link->type;
> >          avpriv_set_pts_info(st, 64, link->time_base.num,
> link->time_base.den);
> >          if (link->type == AVMEDIA_TYPE_VIDEO) {
> > +            lavfi->video_time_base = link->time_base;
> > +
> >              st->codecpar->codec_id   = AV_CODEC_ID_RAWVIDEO;
> >              st->codecpar->format     = link->format;
> >              st->codecpar->width      = link->w;
> > @@ -373,8 +376,14 @@ static int create_subcc_packet(AVFormatContext
> *avctx, AVFrame *frame,
> >      if ((ret = av_new_packet(&lavfi->subcc_packet, sd->size)) < 0)
> >          return ret;
> >      memcpy(lavfi->subcc_packet.data, sd->data, sd->size);
> > +
> > +    AVRational time_base = lavfi->video_time_base;
>
> likely triggers compiler warning
>
>
> > +
> > +    double adjust_factor = time_base.den / (90000.0 * time_base.num);
>
> floating point is not needed and not ok due to binary non portability
> theres av_rescale*
>
> also this breaks make fate
>
> do you have a testcase that this fixes ?
>
> [...]
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> Freedom in capitalist society always remains about the same as it was in
> ancient Greek republics: Freedom for slave owners. -- Vladimir Lenin
>
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