The generic code in utils.c sets the AVFrame.pkt_dts field from the
packet it was supposedly decoded. This does not have to be true for a
fully asynchronous decoder like mmaldec. It could be overwritten with an
incorrect value. Even if the decoder doesn't determine the DTS (but sets
it to AV_NOPTS_VALUE), it's impossible to determine a correct value in
utils.c.
Decoders can now be marked with FF_CODEC_CAP_SETS_PKT_DTS, in which case
utils.c won't overwrite the field. The decoders are expected to set this
field (even if they only set it to AV_NOPTS_VALUE).
---
libavcodec/internal.h | 5 ++++-
libavcodec/mmaldec.c | 1 +
libavcodec/utils.c | 3 ++-
3 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/libavcodec/internal.h b/libavcodec/internal.h
index fc90632..3ef70b7 100644
--- a/libavcodec/internal.h
+++ b/libavcodec/internal.h
@@ -46,7 +46,10 @@
* all.
*/
#define FF_CODEC_CAP_INIT_CLEANUP (1 << 1)
-
+/**
+ * whether the decoder sets AVFrame.pkt_dts itself
+ */
+#define FF_CODEC_CAP_SETS_PKT_DTS (1 << 2)
#ifdef DEBUG
# define ff_dlog(ctx, ...) av_log(ctx, AV_LOG_DEBUG, __VA_ARGS__)
diff --git a/libavcodec/mmaldec.c b/libavcodec/mmaldec.c
index f4bf921..a23a97f 100644
--- a/libavcodec/mmaldec.c
+++ b/libavcodec/mmaldec.c
@@ -792,6 +792,7 @@ AVCodec ff_h264_mmal_decoder = {
.flush = ffmmal_flush,
.priv_class = &ffmmaldec_class,
.capabilities = AV_CODEC_CAP_DELAY,
+ .caps_internal = FF_CODEC_CAP_SETS_PKT_DTS,
.pix_fmts = (const enum AVPixelFormat[]) { AV_PIX_FMT_MMAL,
AV_PIX_FMT_YUV420P,
AV_PIX_FMT_NONE},
diff --git a/libavcodec/utils.c b/libavcodec/utils.c
index 1d718b2..a94e4a6 100644
--- a/libavcodec/utils.c
+++ b/libavcodec/utils.c
@@ -1482,7 +1482,8 @@ int attribute_align_arg
avcodec_decode_video2(AVCodecContext *avctx, AVFrame *pi
else {
ret = avctx->codec->decode(avctx, picture, got_picture_ptr,
avpkt);
- picture->pkt_dts = avpkt->dts;
+ if (!(avctx->codec->caps_internal & FF_CODEC_CAP_SETS_PKT_DTS))
+ picture->pkt_dts = avpkt->dts;
/* get_buffer is supposed to set frame parameters */
if (!(avctx->codec->capabilities & AV_CODEC_CAP_DR1)) {
picture->sample_aspect_ratio = avctx->sample_aspect_ratio;
--
2.5.1
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