[FFmpeg-devel] [PATCH v2] avcodec/mediacodecdec: work around for decoding h264 with coded fields

[Aman Gupta]

From: Aman Gupta <aman at tmm1.net>

This is a hacky work-around for #7092, where the lavc h264
parser splits coded fields into separate video packets, only one
of which has a PTS set.

The MediaCodec#queueInputBuffer API expects a PTS along with
incoming video packets, and breaks badly when the PTS is missing
or incorrect (previously it would be passed in as AV_NOPTS_VALUE,
but the same breakage happens if you pass in 0 instead).

Since it seems there's no easy fix for #7092, this patch stores
the previous PTS in the decoder context and re-uses it for the
second packet. This emulates the behavior of other Android video
players that don't split the coded fields, and pass them as a single
buffer with the same timestamp.

Signed-off-by: Aman Gupta <aman at tmm1.net>
---
 libavcodec/mediacodecdec_common.c | 9 +++++++++
 libavcodec/mediacodecdec_common.h | 2 ++
 2 files changed, 11 insertions(+)

diff --git a/libavcodec/mediacodecdec_common.c b/libavcodec/mediacodecdec_common.c
index 40a2ee6778..80cbb7afbd 100644
--- a/libavcodec/mediacodecdec_common.c
+++ b/libavcodec/mediacodecdec_common.c
@@ -448,6 +448,7 @@ static int mediacodec_dec_flush_codec(AVCodecContext *avctx, MediaCodecDecContex
     s->eos = 0;
     atomic_fetch_add(&s->serial, 1);
     atomic_init(&s->hw_buffer_count, 0);
+    s->last_pts = AV_NOPTS_VALUE;
     s->current_input_buffer = -1;
 
     status = ff_AMediaCodec_flush(codec);
@@ -476,6 +477,7 @@ int ff_mediacodec_dec_init(AVCodecContext *avctx, MediaCodecDecContext *s,
     atomic_init(&s->refcount, 1);
     atomic_init(&s->hw_buffer_count, 0);
     atomic_init(&s->serial, 1);
+    s->last_pts = AV_NOPTS_VALUE;
     s->current_input_buffer = -1;
 
     pix_fmt = ff_get_format(avctx, pix_fmts);
@@ -609,6 +611,13 @@ int ff_mediacodec_dec_send(AVCodecContext *avctx, MediaCodecDecContext *s,
         }
 
         pts = pkt->pts;
+        if (pts == AV_NOPTS_VALUE && s->last_pts != AV_NOPTS_VALUE) {
+            pts = s->last_pts;
+        } else if (pts == AV_NOPTS_VALUE) {
+            av_log(avctx, AV_LOG_WARNING, "Packet is missing PTS!\n");
+            pts = 0;
+        }
+        s->last_pts = pkt->pts;
         if (pts != AV_NOPTS_VALUE && avctx->pkt_timebase.num && avctx->pkt_timebase.den) {
             pts = av_rescale_q(pts, avctx->pkt_timebase, AV_TIME_BASE_Q);
         }
diff --git a/libavcodec/mediacodecdec_common.h b/libavcodec/mediacodecdec_common.h
index d280236b8e..9f22006e12 100644
--- a/libavcodec/mediacodecdec_common.h
+++ b/libavcodec/mediacodecdec_common.h
@@ -69,6 +69,8 @@ typedef struct MediaCodecDecContext {
     bool delay_flush;
     atomic_int serial;
 
+    int64_t last_pts;
+
 } MediaCodecDecContext;
 
 int ff_mediacodec_dec_init(AVCodecContext *avctx,
-- 
2.14.2