timecodestamper: Fix up handling/queueing of LTC timecodes

Directly read them out of the decoder as soon as we passed audio and then store them in a queue that we handle internally together with their timestamps. This cleans up memory management and gives us proper control over the queue instead of guessing how the queue inside the LTC decoder actually works and when it overflows.
2024-11-23 18:21:04 +00:00 · 2020-01-09 17:41:55 +02:00 · 2020-01-09 17:41:55 +02:00 · d7bb5b8a16
commit d7bb5b8a16
parent 0a53f6560a
2 changed files with 180 additions and 156 deletions
--- a/gst/timecode/gsttimecodestamper.c
+++ b/gst/timecode/gsttimecodestamper.c
@ -127,6 +127,12 @@ static void gst_timecodestamper_release_pad (GstElement * element,
    GstPad * pad);

 #if HAVE_LTC
+typedef struct
+{
+  GstClockTime running_time;
+  GstVideoTimeCode timecode;
+} TimestampedTimecode;
+
 static gboolean gst_timecodestamper_query (GstBaseTransform * trans,
    GstPadDirection direction, GstQuery * query);

@ -350,8 +356,7 @@ gst_timecodestamper_init (GstTimeCodeStamper * timecodestamper)
  timecodestamper->ltc_first_running_time = GST_CLOCK_TIME_NONE;
  timecodestamper->ltc_current_running_time = GST_CLOCK_TIME_NONE;

-  timecodestamper->ltc_current_tc = NULL;
-  timecodestamper->ltc_current_tc_running_time = GST_CLOCK_TIME_NONE;
+  g_queue_init (&timecodestamper->ltc_current_tcs);
  timecodestamper->ltc_internal_tc = NULL;
  timecodestamper->ltc_internal_running_time = GST_CLOCK_TIME_NONE;
  timecodestamper->ltc_dec = NULL;
@ -409,9 +414,12 @@ gst_timecodestamper_dispose (GObject * object)
  g_cond_clear (&timecodestamper->ltc_cond_video);
  g_cond_clear (&timecodestamper->ltc_cond_audio);
  g_mutex_clear (&timecodestamper->mutex);
-  if (timecodestamper->ltc_current_tc != NULL) {
-    gst_video_time_code_free (timecodestamper->ltc_current_tc);
-    timecodestamper->ltc_current_tc = NULL;
+  {
+    TimestampedTimecode *tc;
+    while ((tc = g_queue_pop_tail (&timecodestamper->ltc_current_tcs))) {
+      gst_video_time_code_clear (&tc->timecode);
+      g_free (tc);
+    }
  }
  if (timecodestamper->ltc_internal_tc != NULL) {
    gst_video_time_code_free (timecodestamper->ltc_internal_tc);
@ -465,13 +473,18 @@ gst_timecodestamper_set_property (GObject * object, guint prop_id,
      timecodestamper->ltc_daily_jam = g_value_dup_boxed (value);

 #if HAVE_LTC
-      if (timecodestamper->ltc_current_tc) {
-        if (timecodestamper->ltc_current_tc->config.latest_daily_jam) {
-          g_date_time_unref (timecodestamper->ltc_current_tc->config.
-              latest_daily_jam);
+      {
+        GList *l;
+
+        for (l = timecodestamper->ltc_current_tcs.head; l; l = l->next) {
+          TimestampedTimecode *tc = l->data;
+
+          if (tc->timecode.config.latest_daily_jam) {
+            g_date_time_unref (tc->timecode.config.latest_daily_jam);
+          }
+          tc->timecode.config.latest_daily_jam =
+              g_date_time_ref (timecodestamper->ltc_daily_jam);
        }
-        timecodestamper->ltc_current_tc->config.latest_daily_jam =
-            g_date_time_ref (timecodestamper->ltc_daily_jam);
      }

      if (timecodestamper->ltc_internal_tc) {
@ -626,11 +639,13 @@ gst_timecodestamper_stop (GstBaseTransform * trans)
  }
  timecodestamper->ltc_internal_running_time = GST_CLOCK_TIME_NONE;

-  if (timecodestamper->ltc_current_tc != NULL) {
-    gst_video_time_code_free (timecodestamper->ltc_current_tc);
-    timecodestamper->ltc_current_tc = NULL;
+  {
+    TimestampedTimecode *tc;
+    while ((tc = g_queue_pop_tail (&timecodestamper->ltc_current_tcs))) {
+      gst_video_time_code_clear (&tc->timecode);
+      g_free (tc);
+    }
  }
-  timecodestamper->ltc_current_tc_running_time = GST_CLOCK_TIME_NONE;

  if (timecodestamper->ltc_dec) {
    ltc_decoder_free (timecodestamper->ltc_dec);
@ -678,9 +693,15 @@ gst_timecodestamper_update_drop_frame (GstTimeCodeStamper * timecodestamper)
      timecodestamper->rtc_tc->config.flags |=
          GST_VIDEO_TIME_CODE_FLAGS_DROP_FRAME;
 #if HAVE_LTC
-    if (timecodestamper->ltc_current_tc)
-      timecodestamper->ltc_current_tc->config.flags |=
-          GST_VIDEO_TIME_CODE_FLAGS_DROP_FRAME;
+    {
+      GList *l;
+
+      for (l = timecodestamper->ltc_current_tcs.head; l; l = l->next) {
+        TimestampedTimecode *tc = l->data;
+
+        tc->timecode.config.flags |= GST_VIDEO_TIME_CODE_FLAGS_DROP_FRAME;
+      }
+    }
    if (timecodestamper->ltc_internal_tc)
      timecodestamper->ltc_internal_tc->config.flags |=
          GST_VIDEO_TIME_CODE_FLAGS_DROP_FRAME;
@ -693,9 +714,15 @@ gst_timecodestamper_update_drop_frame (GstTimeCodeStamper * timecodestamper)
      timecodestamper->rtc_tc->config.flags &=
          ~GST_VIDEO_TIME_CODE_FLAGS_DROP_FRAME;
 #if HAVE_LTC
-    if (timecodestamper->ltc_current_tc)
-      timecodestamper->ltc_current_tc->config.flags &=
-          ~GST_VIDEO_TIME_CODE_FLAGS_DROP_FRAME;
+    {
+      GList *l;
+
+      for (l = timecodestamper->ltc_current_tcs.head; l; l = l->next) {
+        TimestampedTimecode *tc = l->data;
+
+        tc->timecode.config.flags &= ~GST_VIDEO_TIME_CODE_FLAGS_DROP_FRAME;
+      }
+    }
    if (timecodestamper->ltc_internal_tc)
      timecodestamper->ltc_internal_tc->config.flags &=
          ~GST_VIDEO_TIME_CODE_FLAGS_DROP_FRAME;
@ -705,7 +732,8 @@ gst_timecodestamper_update_drop_frame (GstTimeCodeStamper * timecodestamper)

 static void
 gst_timecodestamper_update_timecode_framerate (GstTimeCodeStamper *
-    timecodestamper, const GstVideoInfo * vinfo, GstVideoTimeCode * timecode)
+    timecodestamper, const GstVideoInfo * vinfo, GstVideoTimeCode * timecode,
+    gboolean is_ltc)
 {
  guint64 nframes;
  GstClockTime time;
@ -724,22 +752,27 @@ gst_timecodestamper_update_timecode_framerate (GstTimeCodeStamper *
          timecodestamper->vinfo.fps_n == 60000))
    tc_flags |= GST_VIDEO_TIME_CODE_FLAGS_DROP_FRAME;

-  nframes = gst_video_time_code_frames_since_daily_jam (timecode);
-  time =
-      gst_util_uint64_scale (nframes, GST_SECOND * timecodestamper->vinfo.fps_d,
-      timecodestamper->vinfo.fps_n);
-  jam =
-      timecode->config.latest_daily_jam ? g_date_time_ref (timecode->
-      config.latest_daily_jam) : NULL;
-  gst_video_time_code_clear (timecode);
-  gst_video_time_code_init (timecode, timecodestamper->vinfo.fps_n,
-      timecodestamper->vinfo.fps_d, jam, tc_flags, 0, 0, 0, 0, 0);
-  if (jam)
-    g_date_time_unref (jam);
+  /* If this is an LTC timecode and we have no framerate yet in there then
+   * just do nothing. We're going to set the framerate at a later time */
+  if (timecode->config.fps_d != 0 || !is_ltc) {
+    nframes = gst_video_time_code_frames_since_daily_jam (timecode);
+    time =
+        gst_util_uint64_scale (nframes,
+        GST_SECOND * timecodestamper->vinfo.fps_d,
+        timecodestamper->vinfo.fps_n);
+    jam =
+        timecode->config.latest_daily_jam ? g_date_time_ref (timecode->
+        config.latest_daily_jam) : NULL;
+    gst_video_time_code_clear (timecode);
+    gst_video_time_code_init (timecode, timecodestamper->vinfo.fps_n,
+        timecodestamper->vinfo.fps_d, jam, tc_flags, 0, 0, 0, 0, 0);
+    if (jam)
+      g_date_time_unref (jam);

-  nframes =
-      gst_util_uint64_scale (time, vinfo->fps_n, GST_SECOND * vinfo->fps_d);
-  gst_video_time_code_add_frames (timecode, nframes);
+    nframes =
+        gst_util_uint64_scale (time, vinfo->fps_n, GST_SECOND * vinfo->fps_d);
+    gst_video_time_code_add_frames (timecode, nframes);
+  }
 }

 /* Must be called with object lock */
@ -753,17 +786,25 @@ gst_timecodestamper_update_framerate (GstTimeCodeStamper * timecodestamper,
    return FALSE;

  gst_timecodestamper_update_timecode_framerate (timecodestamper, vinfo,
-      timecodestamper->internal_tc);
+      timecodestamper->internal_tc, FALSE);
  gst_timecodestamper_update_timecode_framerate (timecodestamper, vinfo,
-      timecodestamper->last_tc);
+      timecodestamper->last_tc, FALSE);
  gst_timecodestamper_update_timecode_framerate (timecodestamper, vinfo,
-      timecodestamper->rtc_tc);
+      timecodestamper->rtc_tc, FALSE);

 #if HAVE_LTC
+  {
+    GList *l;
+
+    for (l = timecodestamper->ltc_current_tcs.head; l; l = l->next) {
+      TimestampedTimecode *tc = l->data;
+
+      gst_timecodestamper_update_timecode_framerate (timecodestamper, vinfo,
+          &tc->timecode, TRUE);
+    }
+  }
  gst_timecodestamper_update_timecode_framerate (timecodestamper, vinfo,
-      timecodestamper->ltc_current_tc);
-  gst_timecodestamper_update_timecode_framerate (timecodestamper, vinfo,
-      timecodestamper->ltc_internal_tc);
+      timecodestamper->ltc_internal_tc, FALSE);
 #endif

  return TRUE;
@ -1174,7 +1215,7 @@ gst_timecodestamper_transform_ip (GstBaseTransform * vfilter,
  if (timecodestamper->ltcpad) {
    GstClockTime frame_duration;
    gchar *tc_str;
-    LTCFrameExt ltc_frame;
+    TimestampedTimecode *ltc_tc;
    gboolean updated_internal = FALSE;

    frame_duration = gst_util_uint64_scale_int_ceil (GST_SECOND,
@ -1236,69 +1277,35 @@ gst_timecodestamper_transform_ip (GstBaseTransform * vfilter,

    GST_OBJECT_LOCK (timecodestamper);
    /* Take timecodes out of the queue until we're at the current video
-     * position, but first check the last timecode we took out of the queue
-     * if any. */
-    while (timecodestamper->ltc_dec && (timecodestamper->ltc_current_tc
-            || ltc_decoder_read (timecodestamper->ltc_dec, &ltc_frame) == 1)) {
-      GstVideoTimeCode ltc_read_tc, *ltc_read_tc_ptr = NULL;
-      GstClockTime ltc_running_time;
-
-      memset (&ltc_read_tc, 0, sizeof (ltc_read_tc));
-
-      if (timecodestamper->ltc_current_tc) {
-        ltc_running_time = timecodestamper->ltc_current_tc_running_time;
-        ltc_read_tc_ptr = timecodestamper->ltc_current_tc;
-
-        tc_str =
-            gst_video_time_code_to_string (timecodestamper->ltc_current_tc);
-        GST_INFO_OBJECT (timecodestamper,
-            "Using previous LTC timecode %s at %" GST_TIME_FORMAT, tc_str,
-            GST_TIME_ARGS (ltc_running_time));
-        g_free (tc_str);
-      } else {
-        SMPTETimecode stc;
-        gint fps_n_div;
-
-        if (ltc_frame.off_start < 0) {
-          GstClockTime offset =
-              gst_util_uint64_scale (GST_SECOND, -ltc_frame.off_start,
-              timecodestamper->ainfo.rate);
-
-          if (offset > timecodestamper->ltc_first_running_time)
-            ltc_running_time = 0;
-          else
-            ltc_running_time = timecodestamper->ltc_first_running_time - offset;
-        } else {
-          ltc_running_time = timecodestamper->ltc_first_running_time +
-              gst_util_uint64_scale (GST_SECOND, ltc_frame.off_start,
-              timecodestamper->ainfo.rate);
-        }
-
-        ltc_frame_to_time (&stc, &ltc_frame.ltc, 0);
-        GST_INFO_OBJECT (timecodestamper,
-            "Got LTC timecode %02d:%02d:%02d:%02d at %" GST_TIME_FORMAT,
-            stc.hours, stc.mins, stc.secs, stc.frame,
-            GST_TIME_ARGS (ltc_running_time));
-        fps_n_div =
+     * position. */
+    while ((ltc_tc = g_queue_pop_head (&timecodestamper->ltc_current_tcs))) {
+      /* First update framerate and flags according to the video stream if not
+       * done yet */
+      if (ltc_tc->timecode.config.fps_d == 0) {
+        gint fps_n_div =
            ((gdouble) timecodestamper->vinfo.fps_n) /
            timecodestamper->vinfo.fps_d > 30 ? 2 : 1;

-        gst_video_time_code_clear (&ltc_read_tc);
-        gst_video_time_code_init (&ltc_read_tc,
-            timecodestamper->vinfo.fps_n / fps_n_div,
-            timecodestamper->vinfo.fps_d,
-            timecodestamper->ltc_daily_jam,
-            tc_flags, stc.hours, stc.mins, stc.secs, stc.frame, 0);
-
-        ltc_read_tc_ptr = &ltc_read_tc;
+        ltc_tc->timecode.config.flags = tc_flags;
+        ltc_tc->timecode.config.fps_n =
+            timecodestamper->vinfo.fps_n / fps_n_div;
+        ltc_tc->timecode.config.fps_d = timecodestamper->vinfo.fps_d;
      }

+      tc_str = gst_video_time_code_to_string (&ltc_tc->timecode);
+      GST_INFO_OBJECT (timecodestamper,
+          "Retrieved LTC timecode %s at %" GST_TIME_FORMAT
+          " (%u timecodes queued)", tc_str,
+          GST_TIME_ARGS (ltc_tc->running_time),
+          g_queue_get_length (&timecodestamper->ltc_current_tcs));
+      g_free (tc_str);
+
      /* A timecode frame that starts +/- half a frame to the
       * video frame is considered belonging to that video frame.
       *
       * If it's further ahead than half a frame duration, break out of
       * the loop here and reconsider on the next frame. */
-      if (ABSDIFF (running_time, ltc_running_time) <= frame_duration / 2) {
+      if (ABSDIFF (running_time, ltc_tc->running_time) <= frame_duration / 2) {
        /* If we're resyncing LTC in general, directly replace the current
         * LTC timecode with the new one we read. Otherwise we'll continue
         * counting based on the previous timecode we had
@ -1306,46 +1313,39 @@ gst_timecodestamper_transform_ip (GstBaseTransform * vfilter,
        if (timecodestamper->ltc_auto_resync) {
          if (timecodestamper->ltc_internal_tc)
            gst_video_time_code_free (timecodestamper->ltc_internal_tc);
-          if (gst_video_time_code_is_valid (ltc_read_tc_ptr)) {
+          if (gst_video_time_code_is_valid (&ltc_tc->timecode)) {
            timecodestamper->ltc_internal_tc =
-                gst_video_time_code_copy (ltc_read_tc_ptr);
-            timecodestamper->ltc_internal_running_time = running_time;
+                gst_video_time_code_copy (&ltc_tc->timecode);
+            timecodestamper->ltc_internal_running_time = ltc_tc->running_time;
            updated_internal = TRUE;
            GST_INFO_OBJECT (timecodestamper, "Resynced internal LTC counter");
          } else {
-            tc_str = gst_video_time_code_to_string (ltc_read_tc_ptr);
+            tc_str = gst_video_time_code_to_string (&ltc_tc->timecode);
            GST_INFO_OBJECT (timecodestamper, "Invalid LTC timecode %s",
                tc_str);
            g_free (tc_str);
          }
        }

-        /* And store it for the next frame in case it has more or less the
-         * same running time */
-        timecodestamper->ltc_current_tc =
-            gst_video_time_code_copy (ltc_read_tc_ptr);
-        timecodestamper->ltc_current_tc_running_time = ltc_running_time;
-        gst_video_time_code_clear (&ltc_read_tc);
+        /* And store it back for the next frame in case it has more or less
+         * the same running time */
+        g_queue_push_head (&timecodestamper->ltc_current_tcs,
+            g_steal_pointer (&ltc_tc));
        break;
-      } else if (ltc_running_time > running_time
-          && ltc_running_time - running_time > frame_duration / 2) {
-        /* Store it for the next frame */
-        timecodestamper->ltc_current_tc =
-            gst_video_time_code_copy (ltc_read_tc_ptr);
-        timecodestamper->ltc_current_tc_running_time = ltc_running_time;
-        gst_video_time_code_clear (&ltc_read_tc);
+      } else if (ltc_tc->running_time > running_time
+          && ltc_tc->running_time - running_time > frame_duration / 2) {
+        /* Store it back for the next frame */
+        g_queue_push_head (&timecodestamper->ltc_current_tcs,
+            g_steal_pointer (&ltc_tc));
+        ltc_tc = NULL;
        break;
      }

      /* otherwise it's in the past and we need to consider the next
-       * timecode. Forget the current timecode and read a new one */
-      if (timecodestamper->ltc_current_tc) {
-        gst_video_time_code_free (timecodestamper->ltc_current_tc);
-        timecodestamper->ltc_current_tc = NULL;
-        timecodestamper->ltc_current_tc_running_time = GST_CLOCK_TIME_NONE;
-      }
-
-      gst_video_time_code_clear (&ltc_read_tc);
+       * timecode. Read a new one */
+      gst_video_time_code_clear (&ltc_tc->timecode);
+      g_free (ltc_tc);
+      ltc_tc = NULL;
    }

    /* If we didn't update from LTC above, increment our internal timecode
@ -1578,11 +1578,13 @@ gst_timecodestamper_release_pad (GstElement * element, GstPad * pad)
  }
  timecodestamper->ltc_internal_running_time = GST_CLOCK_TIME_NONE;

-  if (timecodestamper->ltc_current_tc != NULL) {
-    gst_video_time_code_free (timecodestamper->ltc_current_tc);
-    timecodestamper->ltc_current_tc = NULL;
+  {
+    TimestampedTimecode *tc;
+    while ((tc = g_queue_pop_tail (&timecodestamper->ltc_current_tcs))) {
+      gst_video_time_code_clear (&tc->timecode);
+      g_free (tc);
+    }
  }
-  timecodestamper->ltc_current_tc_running_time = GST_CLOCK_TIME_NONE;
  GST_OBJECT_UNLOCK (timecodestamper);

  gst_pad_set_active (pad, FALSE);
@ -1685,13 +1687,12 @@ gst_timecodestamper_ltcpad_chain (GstPad * pad,

  running_time = gst_segment_to_running_time (&timecodestamper->ltc_segment,
      GST_FORMAT_TIME, timestamp);
-  timecodestamper->ltc_current_running_time = running_time + duration;

  GST_DEBUG_OBJECT (timecodestamper,
      "Handling LTC audio buffer at %" GST_TIME_FORMAT " - %" GST_TIME_FORMAT
      " (offset %" G_GUINT64_FORMAT ")",
      GST_TIME_ARGS (running_time),
-      GST_TIME_ARGS (timecodestamper->ltc_current_running_time),
+      GST_TIME_ARGS (running_time + duration),
      (guint64) timecodestamper->ltc_total);

  if (timecodestamper->ltc_total == 0) {
@ -1704,47 +1705,71 @@ gst_timecodestamper_ltcpad_chain (GstPad * pad,
  timecodestamper->ltc_total += map.size;
  gst_buffer_unmap (buffer, &map);

+  /* Now read all the timecodes from the decoder that are currently available
+   * and store them in our own queue, which gives us more control over how
+   * things are working. */
+  {
+    LTCFrameExt ltc_frame;
+
+    while (ltc_decoder_read (timecodestamper->ltc_dec, &ltc_frame) == 1) {
+      SMPTETimecode stc;
+      TimestampedTimecode *ltc_tc;
+      GstClockTime ltc_running_time;
+
+      if (ltc_frame.off_start < 0) {
+        GstClockTime offset =
+            gst_util_uint64_scale (GST_SECOND, -ltc_frame.off_start,
+            timecodestamper->ainfo.rate);
+
+        if (offset > timecodestamper->ltc_first_running_time)
+          ltc_running_time = 0;
+        else
+          ltc_running_time = timecodestamper->ltc_first_running_time - offset;
+      } else {
+        ltc_running_time = timecodestamper->ltc_first_running_time +
+            gst_util_uint64_scale (GST_SECOND, ltc_frame.off_start,
+            timecodestamper->ainfo.rate);
+      }
+
+      ltc_frame_to_time (&stc, &ltc_frame.ltc, 0);
+      GST_INFO_OBJECT (timecodestamper,
+          "Got LTC timecode %02d:%02d:%02d:%02d at %" GST_TIME_FORMAT,
+          stc.hours, stc.mins, stc.secs, stc.frame,
+          GST_TIME_ARGS (ltc_running_time));
+
+      ltc_tc = g_new0 (TimestampedTimecode, 1);
+      ltc_tc->running_time = ltc_running_time;
+      /* We fill in the framerate and other metadata later */
+      gst_video_time_code_init (&ltc_tc->timecode,
+          0, 0, timecodestamper->ltc_daily_jam, 0,
+          stc.hours, stc.mins, stc.secs, stc.frame, 0);
+
+      g_queue_push_tail (&timecodestamper->ltc_current_tcs,
+          g_steal_pointer (&ltc_tc));
+    }
+  }
+
  /* Notify the video streaming thread that new data is available */
  g_cond_signal (&timecodestamper->ltc_cond_video);

  /* Wait until video has caught up, if needed */
  if (timecodestamper->audio_live) {
-    /* In live-mode, do no waiting but we need to drop things from the LTC
-     * decoder queue as otherwise we'll end up reading old items as new if the
-     * ringbuffer inside it overflows! */
-    while (ltc_decoder_queue_length (timecodestamper->ltc_dec) >
-        3 * DEFAULT_LTC_QUEUE / 4) {
-      LTCFrameExt ltc_frame;
-      GST_WARNING_OBJECT (timecodestamper,
-          "Dropping old LTC timecode because of too slow video");
-      ltc_decoder_read (timecodestamper->ltc_dec, &ltc_frame);
-    }
+    /* In live-mode, do no waiting as we're guaranteed to be more or less in
+     * sync (~latency) with the video */
  } else {
    /* If we're ahead of the video, wait until the video has caught up.
     * Otherwise don't wait and drop any too old items from the ringbuffer */
    while ((timecodestamper->video_current_running_time == GST_CLOCK_TIME_NONE
-            || timecodestamper->ltc_current_running_time >=
+            || running_time + duration >=
            timecodestamper->video_current_running_time)
        && timecodestamper->ltc_dec
-        && ltc_decoder_queue_length (timecodestamper->ltc_dec) >
+        && g_queue_get_length (&timecodestamper->ltc_current_tcs) >
        DEFAULT_LTC_QUEUE / 2 && !timecodestamper->video_eos
        && !timecodestamper->ltc_flushing) {
      GST_TRACE_OBJECT (timecodestamper,
          "Waiting for video to advance, EOS or flushing");
      g_cond_wait (&timecodestamper->ltc_cond_audio, &timecodestamper->mutex);
    }
-
-    while ((timecodestamper->video_current_running_time == GST_CLOCK_TIME_NONE
-            || timecodestamper->ltc_current_running_time <
-            timecodestamper->video_current_running_time)
-        && timecodestamper->ltc_dec
-        && ltc_decoder_queue_length (timecodestamper->ltc_dec) >
-        3 * DEFAULT_LTC_QUEUE / 4) {
-      LTCFrameExt ltc_frame;
-      GST_WARNING_OBJECT (timecodestamper,
-          "Dropping old LTC timecode because of audio being behind");
-      ltc_decoder_read (timecodestamper->ltc_dec, &ltc_frame);
-    }
  }

  if (timecodestamper->ltc_flushing)
--- a/gst/timecode/gsttimecodestamper.h
+++ b/gst/timecode/gsttimecodestamper.h
@ -114,10 +114,9 @@ struct _GstTimeCodeStamper
  GstClockTime ltc_current_running_time;

  /* Protected by object lock */
-  /* Current LTC timecode that we last read close
-   * to our video running time */
-  GstVideoTimeCode *ltc_current_tc;
-  GstClockTime ltc_current_tc_running_time;
+  /* Queue of LTC timecodes we took out of the LTC decoder already
+   * together with their corresponding running times */
+  GQueue ltc_current_tcs;

  /* LTC timecode we last synced to and potentially incremented manually since
   * then */