muxavformat: fix last subtitle persistence in mp4

libav doesn't seems to honor the duration of the subtitle AVPacket.  It
is required to send an "empty" subtitle packet to terminate all
subtitles, including the last one.

diff --git a/libhb/muxavformat.c b/libhb/muxavformat.c
index 7aa9b654a008ce129672fb27590fa929813f41be..ef72130b6ff3b12128a1323ae96a55f42cde50a9 100644 (file)
--- a/libhb/muxavformat.c
+++ b/libhb/muxavformat.c
@@ -1051,7 +1051,29 @@ static int avformatMux(hb_mux_object_t *m, hb_mux_data_t *track, hb_buffer_t *bu
         buf = tmp;
     }
     if (buf == NULL)
+    {
+        if (job->mux == HB_MUX_AV_MP4 && track->type == MUX_TYPE_SUBTITLE)
+        {
+            // Write a final "empty" subtitle to terminate the last
+            // subtitle that was written
+            if (track->duration > 0)
+            {
+                AVPacket empty_pkt;
+                uint8_t empty[2] = {0,0};
+
+                av_init_packet(&empty_pkt);
+                empty_pkt.data = empty;
+                empty_pkt.size = 2;
+                empty_pkt.dts = track->duration;
+                empty_pkt.pts = track->duration;
+                empty_pkt.duration = 90;
+                empty_pkt.convergence_duration = empty_pkt.duration;
+                empty_pkt.stream_index = track->st->index;
+                av_interleaved_write_frame(m->oc, &empty_pkt);
+            }
+        }
         return 0;
+    }
 
     if (track->type == MUX_TYPE_VIDEO && (job->mux & HB_MUX_MASK_MKV) &&
         buf->s.renderOffset < 0)