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, 18 insertions, 6 deletions

diff --git a/video/decode/dec_video.h b/video/decode/dec_video.h
index cb4724af33..9117fceefd 100644
--- a/video/decode/dec_video.h
+++ b/video/decode/dec_video.h
@@ -40,18 +40,31 @@ struct dec_video {
 
     char *decoder_desc;
 
-    void *priv;
+    void *priv; // for free use by vd_driver
 
+    // Last PTS from decoder (set with each vd_driver->decode() call)
+    double codec_pts;
+    int num_codec_pts_problems;
+
+    // Last packet DTS from decoder (passed through from source packets)
+    double codec_dts;
+    int num_codec_dts_problems;
+
+    // PTS sorting (obscure, non-default)
     double buffered_pts[32];
     int num_buffered_pts;
-    double codec_reordered_pts;
-    double prev_codec_reordered_pts;
-    int num_reordered_pts_problems;
     double sorted_pts;
-    double prev_sorted_pts;
     int num_sorted_pts_problems;
+    double unsorted_pts;
+    int num_unsorted_pts_problems;
     int pts_assoc_mode;
 
+    // PTS or DTS of packet last read
+    double last_packet_pdts;
+
+    // Final PTS of previously decoded image
+    double decoded_pts;
+
     // PTS of the last decoded frame (often overwritten by player)
     double pts;
 
@@ -60,7 +73,6 @@ struct dec_video {
     float fps;            // FPS from demuxer or from user override
     float initial_decoder_aspect;
 
-    double last_packet_pdts;
     // State used only by player/video.c
     double last_pts;
 };