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| author | Andreas Rheinhardt <andreas.rheinhardt@outlook.com> | 2022-08-08 16:51:04 +0200 |
|---|---|---|
| committer | Andreas Rheinhardt <andreas.rheinhardt@outlook.com> | 2024-06-12 11:01:07 +0200 |
| commit | 71ff9217f769b03ce3b8081ad596ed777ac24d2f (patch) | |
| tree | 735f0832f7f267a82be3e261b0f943d18f266455 | |
| parent | caac9740f84681f28bc6c6bf285fd0a25dc99060 (diff) | |
| download | ffmpeg-71ff9217f769b03ce3b8081ad596ed777ac24d2f.tar.gz | |
avcodec/mpegpicture: Always reset motion val buffer
Codecs call ff_find_unused_picture() to get the index of
an unused picture; said picture may have buffers left
from using it previously (these buffers are intentionally
not unreferenced so that it might be possible to reuse them;
this is mpegvideo's version of a bufferpool). They should
not make any assumptions about which picture they get.
Yet somehow this is not true when decoding OBMC: Returning
random empty pictures (instead of the first one) leads
to nondeterministic results; similarly, explicitly
rezeroing the buffer before handing it over to the codec
changes the outcome of the h263-obmc tests, but it makes it
independent of the returned pictures. Therefore this commit
does so.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
| -rw-r--r-- | libavcodec/mpegpicture.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/libavcodec/mpegpicture.c b/libavcodec/mpegpicture.c index 88b4d5dec1..06c82880a8 100644 --- a/libavcodec/mpegpicture.c +++ b/libavcodec/mpegpicture.c @@ -245,6 +245,10 @@ int ff_alloc_picture(AVCodecContext *avctx, Picture *pic, MotionEstContext *me, for (i = 0; i < 2; i++) { pic->motion_val[i] = (int16_t (*)[2])pic->motion_val_buf[i]->data + 4; pic->ref_index[i] = pic->ref_index_buf[i]->data; + /* FIXME: The output of H.263 with OBMC depends upon + * the earlier content of the buffer; therefore we + * reset it here. */ + memset(pic->motion_val_buf[i]->data, 0, pic->motion_val_buf[i]->size); } } |