Call ff_fetch_timestamp() for mpeg1/2 when a picture start code is found instead

of calling it at the end of a frame with a large negative offset.
This significantly reduces the maximal distance in container packets between
the point where the first byte of the "access unit" was stored and where
we call ff_fetch_timestamp() thus reducing the constraints on our parser.
Also change the parser from next_frame_offset to cur, this is needed
because now the reference is from container packet start instead of
frame start. (i previously misinterpreted this as bug)

Originally committed as revision 17731 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/mpeg12.c

@@ -2196,7 +2196,7 @@ static void mpeg_decode_gop(AVCodecContext *avctx,
  * Finds the end of the current frame in the bitstream.
  * @return the position of the first byte of the next frame, or -1
  */
-int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)
+int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size, AVCodecParserContext *s)
 {
     int i;
     uint32_t state= pc->state;
@@ -2244,6 +2244,9 @@ int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)
                     return i-3;
                 }
             }
+            if(s && state == PICTURE_START_CODE){
+                ff_fetch_timestamp(s, i-4, 1);
+            }
         }
     }
     pc->state= state;
@@ -2276,7 +2279,7 @@ static int mpeg_decode_frame(AVCodecContext *avctx,
     }
 
     if(s2->flags&CODEC_FLAG_TRUNCATED){
-        int next= ff_mpeg1_find_frame_end(&s2->parse_context, buf, buf_size);
+        int next= ff_mpeg1_find_frame_end(&s2->parse_context, buf, buf_size, NULL);
 
         if( ff_combine_frame(&s2->parse_context, next, (const uint8_t **)&buf, &buf_size) < 0 )
             return buf_size;

libavcodec/mpegvideo.h

@@ -769,7 +769,7 @@ void mpeg1_encode_mb(MpegEncContext *s,
 void ff_mpeg1_encode_init(MpegEncContext *s);
 void ff_mpeg1_encode_slice_header(MpegEncContext *s);
 void ff_mpeg1_clean_buffers(MpegEncContext *s);
-int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size);
+int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size, AVCodecParserContext *s);
 
 extern const uint8_t ff_mpeg4_y_dc_scale_table[32];
 extern const uint8_t ff_mpeg4_c_dc_scale_table[32];

libavcodec/mpegvideo_parser.c

@@ -29,7 +29,6 @@ static void mpegvideo_extract_headers(AVCodecParserContext *s,
 {
     ParseContext1 *pc = s->priv_data;
     const uint8_t *buf_end;
-    const uint8_t *buf_start= buf;
     uint32_t start_code;
     int frame_rate_index, ext_type, bytes_left;
     int frame_rate_ext_n, frame_rate_ext_d;
@@ -44,8 +43,6 @@ static void mpegvideo_extract_headers(AVCodecParserContext *s,
         bytes_left = buf_end - buf;
         switch(start_code) {
         case PICTURE_START_CODE:
-            ff_fetch_timestamp(s, buf-buf_start-4, 1);
-
             if (bytes_left >= 2) {
                 s->pict_type = (buf[1] >> 3) & 7;
             }
@@ -137,7 +134,7 @@ static int mpegvideo_parse(AVCodecParserContext *s,
     if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
         next= buf_size;
     }else{
-        next= ff_mpeg1_find_frame_end(pc, buf, buf_size);
+        next= ff_mpeg1_find_frame_end(pc, buf, buf_size, s);
 
         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
             *poutbuf = NULL;

libavcodec/parser.c

@@ -87,7 +87,7 @@ void ff_fetch_timestamp(AVCodecParserContext *s, int off, int remove){
     s->dts= s->pts= AV_NOPTS_VALUE;
     s->offset= 0;
     for(i = 0; i < AV_PARSER_PTS_NB; i++) {
-        if (   s->next_frame_offset + off >= s->cur_frame_offset[i]
+        if (   s->cur_offset + off >= s->cur_frame_offset[i]
             &&(s->     frame_offset       <  s->cur_frame_offset[i] || !s->frame_offset)
             //check is disabled  becausue mpeg-ts doesnt send complete PES packets
             && /*s->next_frame_offset + off <*/  s->cur_frame_end[i]){