[FFmpeg-devel] [PATCH 2/3] avcodec/vc1dec: Disable error concealment for *IMAGE

Michael Niedermayer michael at niedermayer.cc
Sat Jul 31 20:48:43 EEST 2021


The existing error concealment makes no sense for the image formats, they
use transformed source images which is different from keyframe + MC+difference
for which the error concealment is designed.
Of course feel free to re-enable this if you have a case where it works and
improves vissual results

Fixes: Timeout
Fixes: 36234/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VC1IMAGE_fuzzer-6300306743885824

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
---
 libavcodec/vc1dec.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/libavcodec/vc1dec.c b/libavcodec/vc1dec.c
index 6cd74a09f1..1fb1950ade 100644
--- a/libavcodec/vc1dec.c
+++ b/libavcodec/vc1dec.c
@@ -1121,7 +1121,9 @@ static int vc1_decode_frame(AVCodecContext *avctx, void *data,
             ret = AVERROR_INVALIDDATA;
             goto err;
         }
-        if (!v->field_mode)
+        if (   !v->field_mode
+            && avctx->codec_id != AV_CODEC_ID_WMV3IMAGE
+            && avctx->codec_id != AV_CODEC_ID_VC1IMAGE)
             ff_er_frame_end(&s->er);
     }
 
-- 
2.17.1



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