mpeg4 header parser clenup (needed for parsing of VOL header in avctx->extradata)

Originally committed as revision 1032 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/avcodec.h

@@ -180,6 +180,7 @@ typedef struct AVCodecContext {
      * some codecs need / can use extra-data like huffman tables
      * mjpeg: huffman tables
      * rv10: additional flags
+     * mpeg4: global headers (they can be in the bitstream or here)
      * encoding: set/allocated/freed by lavc.
      * decoding: set/allocated/freed by user.
      */

libavcodec/h263dec.c

@@ -40,8 +40,6 @@ static inline long long rdtsc()
 }
 #endif
 
-const UINT16 ff_mpeg4_resync_prefix[8];
-
 static int h263_decode_init(AVCodecContext *avctx)
 {
     MpegEncContext *s = avctx->priv_data;
@@ -313,7 +311,14 @@ uint64_t time= rdtsc();
     if (s->h263_msmpeg4) {
         ret = msmpeg4_decode_picture_header(s);
     } else if (s->h263_pred) {
-        ret = mpeg4_decode_picture_header(s);
+        if(s->avctx->extradata_size && s->picture_number==0){
+            GetBitContext gb;
+            
+            init_get_bits(&gb, s->avctx->extradata, s->avctx->extradata_size);
+            ret = ff_mpeg4_decode_picture_header(s, &gb);
+        }
+        ret = ff_mpeg4_decode_picture_header(s, &s->gb);
+
         s->has_b_frames= !s->low_delay;
     } else if (s->h263_intel) {
         ret = intel_h263_decode_picture_header(s);

libavcodec/mpegvideo.h

@@ -624,7 +624,9 @@ void h263_encode_init(MpegEncContext *s);
 void h263_decode_init_vlc(MpegEncContext *s);
 int h263_decode_picture_header(MpegEncContext *s);
 int ff_h263_decode_gob_header(MpegEncContext *s);
-int mpeg4_decode_picture_header(MpegEncContext * s);
+int ff_mpeg4_decode_picture_header(MpegEncContext * s, GetBitContext *gb);
+
+
 int intel_h263_decode_picture_header(MpegEncContext *s);
 int ff_h263_decode_mb(MpegEncContext *s,
                       DCTELEM block[6][64]);