adaptivedemux2: Fixes for period switching in the output loop

Close some race conditions in switching to the next period,
by ensuring the tracks are completely drained first and by
not outputting EOS events to the output source pad
if there is another period pending.

Fixes Manifest_MultiPeriod_1080p.mpd some more.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/2838>

subprojects/gst-plugins-good/ext/adaptivedemux2/gstadaptivedemux.c

@@ -744,6 +744,7 @@ gst_adaptive_demux_output_slot_free (GstAdaptiveDemux * demux,
   GstEvent *eos = gst_event_new_eos ();
   GST_DEBUG_OBJECT (slot->pad, "Releasing slot");
 
+  /* FIXME: The slot might not have output any data, caps or segment yet */
   gst_event_set_seqnum (eos, demux->priv->segment_seqnum);
   gst_pad_push_event (slot->pad, eos);
   gst_pad_set_active (slot->pad, FALSE);
@@ -3521,6 +3522,7 @@ gst_adaptive_demux_output_loop (GstAdaptiveDemux * demux)
   GList *tmp;
   GstClockTimeDiff global_output_position = GST_CLOCK_STIME_NONE;
   gboolean wait_for_data = FALSE;
+  gboolean all_tracks_empty;
   GstFlowReturn ret;
 
   GST_DEBUG_OBJECT (demux, "enter");
@@ -3539,6 +3541,8 @@ gst_adaptive_demux_output_loop (GstAdaptiveDemux * demux)
 restart:
   ret = GST_FLOW_OK;
   global_output_position = GST_CLOCK_STIME_NONE;
+  all_tracks_empty = TRUE;
+
   if (wait_for_data) {
     GST_DEBUG_OBJECT (demux, "Waiting for data");
     g_cond_wait (&demux->priv->tracks_add, &demux->priv->tracks_lock);
@@ -3583,6 +3587,11 @@ restart:
       gst_adaptive_demux_track_update_next_position (track);
     }
 
+    GST_TRACE_OBJECT (demux,
+        "Looking at track %s (period %u). next_position %" GST_STIME_FORMAT,
+        track->stream_id, track->period_num,
+        GST_STIME_ARGS (track->next_position));
+
     if (track->next_position != GST_CLOCK_STIME_NONE) {
       if (global_output_position == GST_CLOCK_STIME_NONE)
         global_output_position = track->next_position;
@@ -3590,22 +3599,27 @@ restart:
         global_output_position =
             MIN (global_output_position, track->next_position);
       track->waiting_add = FALSE;
+      all_tracks_empty = FALSE;
     } else if (!track->eos) {
       GST_DEBUG_OBJECT (demux, "Need timed data on track %s (period %u)",
           track->stream_id, track->period_num);
+      all_tracks_empty = FALSE;
       wait_for_data = track->waiting_add = TRUE;
     } else {
       GST_DEBUG_OBJECT (demux,
           "Track %s (period %u) is EOS, not waiting for timed data",
           track->stream_id, track->period_num);
+
+      if (gst_queue_array_get_length (track->queue) > 0) {
+        all_tracks_empty = FALSE;
+      }
     }
   }
 
   if (wait_for_data)
     goto restart;
 
-  if (global_output_position == GST_CLOCK_STIME_NONE
+  if (all_tracks_empty && demux->output_period->has_next_period) {
-      && demux->output_period->has_next_period) {
     GST_DEBUG_OBJECT (demux, "Period %d is drained, switching to next period",
         demux->output_period->period_num);
     if (!gst_adaptive_demux_advance_output_period (demux)) {
@@ -3646,7 +3660,8 @@ restart:
     while (global_output_position == GST_CLOCK_STIME_NONE
         || !slot->pushed_timed_data
         || ((track->next_position != GST_CLOCK_STIME_NONE)
-            && track->next_position <= global_output_position)) {
+            && track->next_position <= global_output_position)
+        || ((track->next_position == GST_CLOCK_STIME_NONE) && track->eos)) {
       GstMiniObject *mo = track_dequeue_data_locked (demux, track, TRUE);
 
       if (!mo) {
@@ -3679,13 +3694,27 @@ restart:
 
       if (GST_IS_EVENT (mo)) {
         GstEvent *event = (GstEvent *) mo;
-        if (GST_EVENT_TYPE (event) == GST_EVENT_GAP)
+        if (GST_EVENT_TYPE (event) == GST_EVENT_GAP) {
           slot->pushed_timed_data = TRUE;
+        } else if (GST_EVENT_TYPE (event) == GST_EVENT_EOS) {
+          /* If there is a pending next period, don't send the EOS */
+          if (demux->output_period->has_next_period) {
+            GST_LOG_OBJECT (demux,
+                "Dropping EOS on track '%s' (period %u) before next period",
+                track->stream_id, track->period_num);
+            gst_event_store_mark_delivered (&track->sticky_events, event);
+            gst_event_unref (event);
+            event = NULL;
+          }
+        }
+
+        if (event != NULL) {
           gst_pad_push_event (slot->pad, gst_event_ref (event));
 
           if (GST_EVENT_IS_STICKY (event))
             gst_event_store_mark_delivered (&track->sticky_events, event);
           gst_event_unref (event);
+        }
       } else if (GST_IS_BUFFER (mo)) {
         GstBuffer *buffer = (GstBuffer *) mo;