movenc: Use start_dts/cts instead of cluster[0] for writing edit lists

This allows writing edit lists even when track->entry == 0, if
the start times have been set.

Signed-off-by: Martin Storsjö <martin@martin.st>

libavformat/movenc.c

@@ -1613,8 +1613,8 @@ static int mov_write_edts_tag(AVIOContext *pb, MOVMuxContext *mov,
                                       track->timescale, AV_ROUND_UP);
     int version = duration < INT32_MAX ? 0 : 1;
     int entry_size, entry_count, size;
-    int64_t delay, start_ct = track->cluster[0].cts;
-    delay = av_rescale_rnd(track->cluster[0].dts + start_ct, MOV_TIMESCALE,
+    int64_t delay, start_ct = track->start_cts;
+    delay = av_rescale_rnd(track->start_dts + start_ct, MOV_TIMESCALE,
                            track->timescale, AV_ROUND_DOWN);
     version |= delay < INT32_MAX ? 0 : 1;
 
@@ -1650,7 +1650,7 @@ static int mov_write_edts_tag(AVIOContext *pb, MOVMuxContext *mov,
          * special meaning. Normally start_ct should end up positive or zero
          * here, but use FFMIN in case dts is a a small positive integer
          * rounded to 0 when represented in MOV_TIMESCALE units. */
-        start_ct  = -FFMIN(track->cluster[0].dts, 0);
+        start_ct  = -FFMIN(track->start_dts, 0);
         /* Note, this delay is calculated from the pts of the first sample,
          * ensuring that we don't reduce the duration for cases with
          * dts<0 pts=0. */
@@ -1774,9 +1774,9 @@ static int mov_write_trak_tag(AVIOContext *pb, MOVMuxContext *mov,
     avio_wb32(pb, 0); /* size */
     ffio_wfourcc(pb, "trak");
     mov_write_tkhd_tag(pb, mov, track, st);
-    if (track->entry &&
+    if (track->start_dts != AV_NOPTS_VALUE &&
         (track->mode == MODE_PSP || track->flags & MOV_TRACK_CTTS ||
-        track->cluster[0].dts || is_clcp_track(track))) {
+        track->start_dts || is_clcp_track(track))) {
         if (mov->use_editlist)
             mov_write_edts_tag(pb, mov, track);  // PSP Movies require edts box
         else if ((track->entry && track->cluster[0].dts) || track->mode == MODE_PSP || is_clcp_track(track))