On 5/2/18, wm4 <nfx...@googlemail.com> wrote: > On Tue, 1 May 2018 17:48:32 +0200 > Paul B Mahol <one...@gmail.com> wrote: > >> This one actually works with hd1080 y4m files when seeking backwards. >> >> Signed-off-by: Paul B Mahol <one...@gmail.com> >> --- >> libavformat/yuv4mpegdec.c | 8 +++----- >> 1 file changed, 3 insertions(+), 5 deletions(-) >> >> diff --git a/libavformat/yuv4mpegdec.c b/libavformat/yuv4mpegdec.c >> index 8662a42a4c..de3d5637fe 100644 >> --- a/libavformat/yuv4mpegdec.c >> +++ b/libavformat/yuv4mpegdec.c >> @@ -317,11 +317,9 @@ static int yuv4_read_seek(AVFormatContext *s, int >> stream_index, >> AVStream *st = s->streams[0]; >> int64_t pos; >> >> - pos = av_rescale_rnd(pts * s->packet_size, >> - st->time_base.num, >> - st->time_base.den * s->packet_size, >> - (flags & AVSEEK_FLAG_BACKWARD) ? AV_ROUND_DOWN : >> AV_ROUND_UP); >> - pos *= s->packet_size; >> + if (flags & AVSEEK_FLAG_BACKWARD) >> + pts -= 1; >> + pos = pts * s->packet_size; >> >> if (avio_seek(s->pb, pos + s->internal->data_offset, SEEK_SET) < 0) >> return -1; > > That seems questionable too. Though I'm not sure if the previous code > is correct. > > In theory, you're supposed to do this: > 1. Determine seek target as accurately as possible > 2. If the seek target is not exact then: > 2a. if AVSEEK_FLAG_FORWARD is set, then round to the next frame > 2b. otherwise, round to the previous frame > > But if pts is in the stream timebase, then 2. can never happen. (And > also, I have no idea what the code removed by this patch does.) > > Regarding mpv, can you just send me a reproducible test case?
Download any hd1080 derf sample and play it until end and than do backstepping, with --no-correct-pts and without. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
