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

diff --git a/libavcodec/vp8.c b/libavcodec/vp8.c
index 1c973d5bed8a1d19e8a32544ec153accbb743726..d9fdd4da441654650f63a032c5e5fe7f86fd3fdb 100644 (file)
--- 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];