Make timestamp interpolation work with mpeg2 field pictures.

Cleaner/simpler solutions are welcome.

Originally committed as revision 12156 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/avcodec.h

@@ -2788,6 +2788,7 @@ typedef struct AVCodecParserContext {
     /* video info */
     int pict_type; /* XXX: Put it back in AVCodecContext. */
     int repeat_pict; /* XXX: Put it back in AVCodecContext. */
+    int parity;
     int64_t pts;     /* pts of the current frame */
     int64_t dts;     /* dts of the current frame */
 

libavcodec/mpegvideo_parser.c

@@ -36,6 +36,7 @@ static void mpegvideo_extract_headers(AVCodecParserContext *s,
     int horiz_size_ext, vert_size_ext, bit_rate_ext;
 //FIXME replace the crap with get_bits()
     s->repeat_pict = 0;
+    s->parity = 0;
     buf_end = buf + buf_size;
     while (buf < buf_end) {
         start_code= -1;
@@ -105,8 +106,11 @@ static void mpegvideo_extract_headers(AVCodecParserContext *s,
 
                         /* the packet only represents half a frame
                            XXX,FIXME maybe find a different solution */
-                        if(picture_structure != 3)
+                        if(picture_structure != 3){
                             s->repeat_pict = -1;
+                            s->parity = picture_structure-1;
+                        }else
+                            s->parity = !top_field_first;
                     }
                     break;
                 }

libavformat/avformat.h

@@ -337,8 +337,8 @@ typedef struct AVStream {
     struct AVCodecParserContext *parser;
 
     int64_t cur_dts;
-    int last_IP_duration;
-    int64_t last_IP_pts;
+    int last_IP_duration[2];
+    int64_t last_IP_pts[2];
     /* av_seek_frame() support */
     AVIndexEntry *index_entries; /**< only used if the format does not
                                     support seeking natively */

libavformat/utils.c

@@ -702,21 +702,30 @@ static void compute_pkt_fields(AVFormatContext *s, AVStream *st,
     /* interpolate PTS and DTS if they are not present */
     if(delay <=1){
         if (presentation_delayed) {
+            int fields= 2 + (pc ? pc->repeat_pict : 0);
+            int field_duration= pkt->duration / fields;
+            int parity= pc ? pc->parity : 0;
             /* DTS = decompression timestamp */
             /* PTS = presentation timestamp */
             if (pkt->dts == AV_NOPTS_VALUE)
-                pkt->dts = st->last_IP_pts;
+                pkt->dts = st->last_IP_pts[parity];
             update_initial_timestamps(s, pkt->stream_index, pkt->dts, pkt->pts);
             if (pkt->dts == AV_NOPTS_VALUE)
                 pkt->dts = st->cur_dts;
 
             /* this is tricky: the dts must be incremented by the duration
             of the frame we are displaying, i.e. the last I- or P-frame */
-            if (st->last_IP_duration == 0)
-                st->last_IP_duration = pkt->duration;
-            st->cur_dts = pkt->dts + st->last_IP_duration;
-            st->last_IP_duration  = pkt->duration;
-            st->last_IP_pts= pkt->pts;
+            st->cur_dts = pkt->dts;
+            for(i=0; i<fields; i++){
+                int p= (parity + i)&1;
+                if(!st->last_IP_duration[p])
+                    st->last_IP_duration[p]= field_duration;
+                st->cur_dts += st->last_IP_duration[p];
+                st->last_IP_pts[p]= pkt->pts;
+                if(pkt->pts != AV_NOPTS_VALUE)
+                    st->last_IP_pts[p] += i*field_duration;
+                st->last_IP_duration[p]= field_duration;
+            }
             /* cannot compute PTS if not present (we can compute it only
             by knowing the future */
         } else if(pkt->pts != AV_NOPTS_VALUE || pkt->dts != AV_NOPTS_VALUE || pkt->duration){
@@ -1014,7 +1023,8 @@ static void av_read_frame_flush(AVFormatContext *s)
             av_parser_close(st->parser);
             st->parser = NULL;
         }
-        st->last_IP_pts = AV_NOPTS_VALUE;
+        st->last_IP_pts[0] =
+        st->last_IP_pts[1] = AV_NOPTS_VALUE;
         st->cur_dts = AV_NOPTS_VALUE; /* we set the current DTS to an unspecified origin */
     }
 }
@@ -1622,7 +1632,8 @@ static void av_estimate_timings_from_pts(AVFormatContext *ic, offset_t old_offse
     for(i=0; i<ic->nb_streams; i++){
         st= ic->streams[i];
         st->cur_dts= st->first_dts;
-        st->last_IP_pts = AV_NOPTS_VALUE;
+        st->last_IP_pts[0] =
+        st->last_IP_pts[1] = AV_NOPTS_VALUE;
     }
 }
 
@@ -2181,7 +2192,8 @@ AVStream *av_new_stream(AVFormatContext *s, int id)
 
     /* default pts setting is MPEG-like */
     av_set_pts_info(st, 33, 1, 90000);
-    st->last_IP_pts = AV_NOPTS_VALUE;
+    st->last_IP_pts[0] =
+    st->last_IP_pts[1] = AV_NOPTS_VALUE;
     for(i=0; i<MAX_REORDER_DELAY+1; i++)
         st->pts_buffer[i]= AV_NOPTS_VALUE;