Ticket #2573: xdcam.patch

libavformat/movenc.c

@@ -1316 +1316 @@
     return update_size(pb, pos);
 }
 
+static int compute_track_delay(MOVTrack *track) {
+    int i;
+    int64_t first_pts, key_frame_pts;
+    MOVIentry *key_frame = NULL;
+
+    // search for the first keyframe within this track
+    for (i = 0; i < track->entry; i++) {
+        if (track->cluster[i].flags & (MOV_SYNC_SAMPLE|MOV_PARTIAL_SYNC_SAMPLE)) {
+            key_frame = &track->cluster[i];
+            break;
+        }
+    }
+    if (!key_frame) {
+        // no keyframe found
+        return 0;
+    }
+
+    // check if after this first keyframe are entries with 'earlier' pts,
+    // which means entries are reordered
+    // we assume entries to be in decoding order
+    first_pts = key_frame_pts = key_frame->dts + key_frame->cts;
+    for (i++; i < track->entry; i++) {
+        int64_t pts = track->cluster[i].dts + track->cluster[i].cts;
+        if (pts >= key_frame_pts)
+            break;
+        first_pts = FFMIN(pts, first_pts);
+    }
+    // diff between pts of the first shown frame and the dts of the first decoded
+    // frame (which is not necessarily equal to 0) is the delay of this track
+    return first_pts - key_frame->dts;
+}
+
+
 static int mov_write_ctts_tag(AVIOContext *pb, MOVTrack *track)
 {
     MOVStts *ctts_entries;
     uint32_t entries = 0;
     uint32_t atom_size;
-    int i;
+    int i, track_delay = 0;
+
+    if(track->mode == MODE_MOV)
+        track_delay = compute_track_delay(track);
 
     ctts_entries = av_malloc((track->entry + 1) * sizeof(*ctts_entries)); /* worst case */
     ctts_entries[0].count = 1;
@@ -1343 +1379 @@
     avio_wb32(pb, entries); /* entry count */
     for (i = 0; i < entries; i++) {
         avio_wb32(pb, ctts_entries[i].count);
-        avio_wb32(pb, ctts_entries[i].duration);
+        avio_wb32(pb, ctts_entries[i].duration - track_delay);
     }
     av_free(ctts_entries);
     return atom_size;
@@ -1810 +1846 @@
     int64_t duration = av_rescale_rnd(track->track_duration, MOV_TIMESCALE,
                                       track->timescale, AV_ROUND_UP);
     int version = duration < INT32_MAX ? 0 : 1;
-    int entry_size, entry_count, size;
+    int entry_size, entry_count, size, idx = 0;
     int64_t delay, start_ct = track->cluster[0].cts;
-    delay = av_rescale_rnd(track->cluster[0].dts + start_ct, MOV_TIMESCALE,
+
+    // compute delay, which is the pts of the first shown frame (not necessarily 0)
+    // as frames might be reordered, we have to iterate
+    delay = track->cluster[0].dts + track->cluster[0].cts;
+    for(int i = 1; i < track->entry; i++) {
+        int64_t pts = track->cluster[i].dts + track->cluster[i].cts;
+        if(pts >= track->cluster[0].dts + track->cluster[0].cts)
+            break;
+        if(pts < delay) {
+            delay = pts;
+            start_ct = pts;
+            idx = i;
+        }
+    }
+
+    delay = av_rescale_rnd(delay, MOV_TIMESCALE,
                            track->timescale, AV_ROUND_DOWN);
     version |= delay < INT32_MAX ? 0 : 1;
 
@@ -1829 +1880 @@
     avio_wb24(pb, 0); /* flags */
 
     avio_wb32(pb, entry_count);
+
     if (delay > 0) { /* add an empty edit to delay presentation */
         if (version == 1) {
             avio_wb64(pb, delay);
@@ -1839 +1891 @@
         }
         avio_wb32(pb, 0x00010000);
     } else {
-        av_assert0(av_rescale_rnd(track->cluster[0].dts, MOV_TIMESCALE, track->timescale, AV_ROUND_DOWN) <= 0);
-        start_ct  = -FFMIN(track->cluster[0].dts, 0); //FFMIN needed due to rounding
+        av_assert0(av_rescale_rnd(track->cluster[idx].dts + track->cluster[idx].cts, MOV_TIMESCALE, track->timescale, AV_ROUND_DOWN) <= 0);
+        start_ct  = -FFMIN(track->cluster[idx].dts + track->cluster[idx].cts, 0); //FFMIN needed due to rounding
         duration += delay;
     }