[FFmpeg-devel] [PATCH] avcodec/ffv1dec_template: Optimize common case in run mode

[Michael Niedermayer]

Fixes: Timeout (14sec -> 9sec)
Fixes: 13398/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_FFV1_fuzzer-5664106709778432

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/ffv1dec_template.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/libavcodec/ffv1dec_template.c b/libavcodec/ffv1dec_template.c
index 1b7f6c4bf5..0b1d176ba1 100644
--- a/libavcodec/ffv1dec_template.c
+++ b/libavcodec/ffv1dec_template.c
@@ -86,11 +86,19 @@ static av_always_inline int RENAME(decode_line)(FFV1Context *s, int w,
                         run_mode = 2;
                     }
                 }
+                if (sample[1][x - 1] == sample[0][x - 1]) {
+                    while (run_count > 1 && w-x > 1) {
+                        sample[1][x] = sample[0][x];
+                        x++;
+                        run_count--;
+                    }
+                } else {
                 while (run_count > 1 && w-x > 1) {
                     sample[1][x] = RENAME(predict)(sample[1] + x, sample[0] + x);
                     x++;
                     run_count--;
                 }
+                }
                 run_count--;
                 if (run_count < 0) {
                     run_mode  = 0;
-- 
2.21.0