vp8: update frame size changes on thread context switches.

This properly synchronizes frame size changes between threads if
subsequent threads abort decoding before frame size is initialized, i.e.
it prevents the thread after that from ping-ponging back to the original
value.

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind

1 files changed, 2 insertions, 0 deletions

diff --git a/libavcodec/vp8.c b/libavcodec/vp8.c
index 1c973d5bed..d9fdd4da44 100644
--- a/libavcodec/vp8.c
+++ b/libavcodec/vp8.c
@@ -1833,6 +1833,8 @@ static int vp8_decode_update_thread_context(AVCodecContext *dst, const AVCodecCo
         (s_src->mb_width != s->mb_width || s_src->mb_height != s->mb_height)) {
         free_buffers(s);
         s->maps_are_invalid = 1;
+        s->mb_width  = s_src->mb_width;
+        s->mb_height = s_src->mb_height;
     }
 
     s->prob[0] = s_src->prob[!s_src->update_probabilities];