Make sure the parsers do not overwrite width/height as this can interfere

with the decoder.
Fixes issue1135.

Originally committed as revision 20736 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/mpeg4video_parser.c

@@ -82,7 +82,7 @@ static int av_mpeg4_decode_header(AVCodecParserContext *s1,
 
     init_get_bits(gb, buf, 8 * buf_size);
     ret = ff_mpeg4_decode_picture_header(s, gb);
-    if (s->width) {
+    if (s->width && (!avctx->width || !avctx->height || !avctx->coded_width || !avctx->coded_height)) {
         avcodec_set_dimensions(avctx, s->width, s->height);
     }
     s1->pict_type= s->pict_type;