vc1dec: prevent v_edge_pos from becoming negative.

[ffmpeg] / libavcodec / mpegvideo_parser.c

diff --git a/libavcodec/mpegvideo_parser.c b/libavcodec/mpegvideo_parser.c
index c112a9484170350ed3c88e79878bde2858599bd3..35a91604d247b6e1584ef283fa86e5e14e9fc3bf 100644 (file)
--- a/libavcodec/mpegvideo_parser.c
+++ b/libavcodec/mpegvideo_parser.c
@@ -56,6 +56,7 @@ static void mpegvideo_extract_headers(AVCodecParserContext *s,
         case PICTURE_START_CODE:
             if (bytes_left >= 2) {
                 s->pict_type = (buf[1] >> 3) & 7;
+                if (bytes_left >= 4)
                 vbv_delay = ((buf[1] & 0x07) << 13) | (buf[2] << 5) | (buf[3]  >> 3);
             }
             break;