video: refactor PTS code, add fall back heuristic to DTS

Refactor the PTS handling code to make it cleaner, and to separate the
bits that use PTS sorting.

Add a heuristic to fall back to DTS if the PTS us non-monotonic. This
code is based on what FFmpeg/Libav use for ffplay/avplay and also
best_effort_timestamp (which is only in FFmpeg). Basically, this 1. just
uses the DTS if PTS is unset, and 2. ignores PTS entirely if PTS is non-
monotonic, but DTS is sorted.

The code is pretty much the same as in Libav [1]. I'm not sure if all of
it is really needed, or if it does more than what the paragraph above
mentions. But maybe it's fine to cargo-cult this.

This heuristic fixes playback of mpeg4 in ogm, which returns packets
with PTS==DTS, even though the PTS timestamps should follow codec
reordering. This is probably a libavformat demuxer bug, but good luck
trying to fix it.

The way vd_lavc.c returns the frame PTS and DTS to dec_video.c is a bit
inelegant, but maybe better than trying to mess the PTS back into the
decoder callback again.

[1] https://git.libav.org/?p=libav.git;a=blob;f=cmdutils.c;h=3f1c667075724c5cde69d840ed5ed7d992898334;hb=fa515c2088e1d082d45741bbd5c05e13b0500804#l1431

1 files changed, 1 insertions, 2 deletions

diff --git a/video/decode/vd_lavc.c b/video/decode/vd_lavc.c
index d29bad6d29..32bbca969f 100644
--- a/video/decode/vd_lavc.c
+++ b/video/decode/vd_lavc.c
@@ -757,7 +757,7 @@ static int decode(struct dec_video *vd, struct demux_packet *packet,
         return 0;
 
     update_image_params(vd, ctx->pic);
-    double out_pts = mp_get_av_frame_pkt_pdts(ctx->pic);
+    mp_get_av_frame_pkt_ts(ctx->pic, &vd->codec_pts, &vd->codec_dts);
 
     // Note: potentially resets ctx->pic as it is transferred to mpi
     struct mp_image *mpi = image_from_decoder(vd);
@@ -769,7 +769,6 @@ static int decode(struct dec_video *vd, struct demux_packet *packet,
 
     struct mp_image_params vo_params;
     mp_image_params_from_image(&vo_params, mpi);
-    mpi->pts = out_pts;
 
     if (!mp_image_params_equals(&vo_params, &ctx->vo_image_params)) {
         mp_image_pool_clear(ctx->non_dr1_pool);