[FFmpeg-devel] [PATCH v2 1/2] libavformat/utils: Interpolate missing timestamps in H264 and HEVC when no b-frames observed

[Andriy Gelman]

From: Andriy Gelman <andriy.gelman at gmail.com>

Fixes Ticket #7895.

Currently, timestamp interpolation is disabled by default in H264 and
HEVC.  This creates playback issues when the demuxer does not output a
valid timestamp. This patch allows interpolation when no b-frames have
been observed during decoding, which fixes playback issues for some
missing timestamp cases.
---
 libavformat/utils.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/libavformat/utils.c b/libavformat/utils.c
index a63d71b0f4..3dd0bf0d66 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -1233,7 +1233,9 @@ static void compute_pkt_fields(AVFormatContext *s, AVStream *st,
     int64_t offset;
     AVRational duration;
     int onein_oneout = st->codecpar->codec_id != AV_CODEC_ID_H264 &&
-                       st->codecpar->codec_id != AV_CODEC_ID_HEVC;
+                       st->codecpar->codec_id != AV_CODEC_ID_HEVC ||
+                       (!st->internal->avctx->max_b_frames &&
+                        st->cur_dts != RELATIVE_TS_BASE); /*skip when no timing info from demuxer */
 
     if (s->flags & AVFMT_FLAG_NOFILLIN)
         return;
@@ -1272,6 +1274,10 @@ static void compute_pkt_fields(AVFormatContext *s, AVStream *st,
     delay = st->internal->avctx->has_b_frames;
     presentation_delayed = 0;
 
+    /*update max_b_frames if delay is larger */
+    if (delay > st->internal->avctx->max_b_frames)
+      st->internal->avctx->max_b_frames = delay;
+
     /* XXX: need has_b_frame, but cannot get it if the codec is
      *  not initialized */
     if (delay &&
@@ -1337,7 +1343,8 @@ static void compute_pkt_fields(AVFormatContext *s, AVStream *st,
             presentation_delayed, av_ts2str(pkt->pts), av_ts2str(pkt->dts), av_ts2str(st->cur_dts),
             pkt->stream_index, pc, pkt->duration, delay, onein_oneout);
 
-    /* Interpolate PTS and DTS if they are not present. We skip H264
+    /* Interpolate PTS and DTS if they are not present. H264/HEVC timestamps are
+     * interpolated only if no b-frames have been observed. Otherwise, we skip H264/HEVC
      * currently because delay and has_b_frames are not reliably set. */
     if ((delay == 0 || (delay == 1 && pc)) &&
         onein_oneout) {
-- 
2.21.0