Hi,
I am encountering frequent crashes with current libav when encoding
live MPEG2 streams. This seems to be caused by the recent
multithreading changes in error_resilience.c.
The problem is, that after the ff_thread_await_progress, picture's
motion_val and ref_index can still sometimes be NULL, which causes the
segfault. I tried to add a simple sanity check (attached) which solves
the problem here, but I don't know if it's a proper solution.
Sample mpeg-ts stream: http://geraldine.fjfi.cvut.cz/~makovicka/stream.dump
To reproduce: ./ffmpeg -y -i stream.dump out.mpg
Regards,
--
Jindrich Makovicka
diff --git a/libavcodec/error_resilience.c b/libavcodec/error_resilience.c
index aea0e15..c939733 100644
--- a/libavcodec/error_resilience.c
+++ b/libavcodec/error_resilience.c
@@ -534,9 +534,19 @@ skip_mean_and_median:
ff_thread_await_progress((AVFrame *) s->last_picture_ptr,
mb_y, 0);
}
- prev_x = s->last_picture.motion_val[0][mot_index][0];
- prev_y = s->last_picture.motion_val[0][mot_index][1];
- prev_ref = s->last_picture.ref_index[0][4*mb_xy];
+
+ if (s->last_picture.motion_val[0]) {
+ prev_x = s->last_picture.motion_val[0][mot_index][0];
+ prev_y = s->last_picture.motion_val[0][mot_index][1];
+ } else {
+ prev_x = s->current_picture.motion_val[0][mot_index][0];
+ prev_y = s->current_picture.motion_val[0][mot_index][1];
+ }
+ if (s->last_picture.ref_index[0]) {
+ prev_ref = s->last_picture.ref_index[0][4*mb_xy];
+ } else {
+ prev_ref = s->current_picture.ref_index[0][4*mb_xy];
+ }
} else {
prev_x = s->current_picture.motion_val[0][mot_index][0];
prev_y = s->current_picture.motion_val[0][mot_index][1];
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