dashdemux: remove buffering message emission from dashdemux

dashdemux shouldn't emit the buffering message as that can pause
the pipeline. It has no proper knowledge of the downstream buffering
status so it can pause the pipeline when it isn't necessary. It should
have an internal buffer for downloading the streams ahead of playback,
but that shouldn't make it able to stop the pipeline for buffering.

A particular case in which this is bad is when a pad switch happens
(changing bitrates for example), the new pads dashdemux creates
will get linked to demuxers and new queues will be created,
these queues are initially empty and dashdemux will quickly
drain its buffers by pushing them to those queues. So it
would have no more buffers internally and would emit a
buffering message with a low ratio, causing the pipeline
to pause when it wouldn't be necessary.

diff --git a/ext/dash/gstdashdemux.c b/ext/dash/gstdashdemux.c
index 1abe9bf..3fa585a 100644 (file)
--- a/ext/dash/gstdashdemux.c
+++ b/ext/dash/gstdashdemux.c
@@ -237,7 +237,6 @@ static gboolean gst_dash_demux_get_next_fragment_set (GstDashDemux * demux);
 
 static void gst_dash_demux_reset (GstDashDemux * demux, gboolean dispose);
 static GstClockTime gst_dash_demux_get_buffering_time (GstDashDemux * demux);
-static float gst_dash_demux_get_buffering_ratio (GstDashDemux * demux);
 static GstCaps *gst_dash_demux_get_input_caps (GstDashDemux * demux,
     GstActiveStream * stream);
 static GstClockTime gst_dash_demux_stream_get_buffering_time (GstDashDemuxStream
@@ -366,7 +365,6 @@ gst_dash_demux_init (GstDashDemux * demux, GstDashDemuxClass * klass)
   demux->downloader = gst_uri_downloader_new ();
 
   /* Properties */
-  demux->min_buffering_time = DEFAULT_MIN_BUFFERING_TIME * GST_SECOND;
   demux->max_buffering_time = DEFAULT_MAX_BUFFERING_TIME * GST_SECOND;
   demux->bandwidth_usage = DEFAULT_BANDWIDTH_USAGE;
   demux->max_bitrate = DEFAULT_MAX_BITRATE;
@@ -393,9 +391,6 @@ gst_dash_demux_set_property (GObject * object, guint prop_id,
   GstDashDemux *demux = GST_DASH_DEMUX (object);
 
   switch (prop_id) {
-    case PROP_MIN_BUFFERING_TIME:
-      demux->min_buffering_time = g_value_get_uint (value) * GST_SECOND;
-      break;
     case PROP_MAX_BUFFERING_TIME:
       demux->max_buffering_time = g_value_get_uint (value) * GST_SECOND;
       break;
@@ -418,10 +413,6 @@ gst_dash_demux_get_property (GObject * object, guint prop_id, GValue * value,
   GstDashDemux *demux = GST_DASH_DEMUX (object);
 
   switch (prop_id) {
-    case PROP_MIN_BUFFERING_TIME:
-      g_value_set_uint (value, demux->min_buffering_time);
-      demux->min_buffering_time *= GST_SECOND;
-      break;
     case PROP_MAX_BUFFERING_TIME:
       g_value_set_uint (value, demux->max_buffering_time);
       demux->max_buffering_time *= GST_SECOND;
@@ -1060,20 +1051,6 @@ gst_dash_demux_stream_loop (GstDashDemux * demux)
 
   GST_LOG_OBJECT (demux, "Starting stream loop");
 
-  if (GST_STATE (demux) == GST_STATE_PLAYING) {
-    if (!demux->end_of_manifest
-        && gst_dash_demux_get_buffering_time (demux) <
-        demux->min_buffering_time) {
-      /* Warn we are below our threshold: this will eventually pause 
-       * the pipeline */
-      GST_WARNING
-          ("Below the threshold: this will eventually pause the pipeline");
-      gst_element_post_message (GST_ELEMENT (demux),
-          gst_message_new_buffering (GST_OBJECT (demux),
-              100 * gst_dash_demux_get_buffering_ratio (demux)));
-    }
-  }
-
   best_time = GST_CLOCK_TIME_NONE;
   selected_stream = NULL;
   pad_switch = TRUE;
@@ -1284,16 +1261,6 @@ gst_dash_demux_stream_get_buffering_time (GstDashDemuxStream * stream)
   return (GstClockTime) level.time;
 }
 
-static float
-gst_dash_demux_get_buffering_ratio (GstDashDemux * demux)
-{
-  float buffering_time = gst_dash_demux_get_buffering_time (demux);
-  if (buffering_time >= demux->min_buffering_time) {
-    return 1.0;
-  } else
-    return buffering_time / demux->min_buffering_time;
-}
-
 /* gst_dash_demux_download_loop:
  * 
  * Loop for the "download' task that fetches fragments based on the 
@@ -1325,16 +1292,9 @@ gst_dash_demux_get_buffering_ratio (GstDashDemux * demux)
 void
 gst_dash_demux_download_loop (GstDashDemux * demux)
 {
-  GstClockTime target_buffering_time;
   GstClock *clock = gst_element_get_clock (GST_ELEMENT (demux));
   gint64 update_period = demux->client->mpd_node->minimumUpdatePeriod;
 
-  /* Wait until the next scheduled download */
-  if (g_cond_timed_wait (GST_TASK_GET_COND (demux->download_task),
-          demux->download_timed_lock, &demux->next_download)) {
-    goto quit;
-  }
-
   if (clock && gst_mpd_client_is_live (demux->client)
       && demux->client->mpd_uri != NULL && update_period != -1) {
     GstFragment *download;
@@ -1413,71 +1373,43 @@ gst_dash_demux_download_loop (GstDashDemux * demux)
   }
 
 
-  /* Target buffering time MUST at least exceeds mimimum buffering time 
-   * by the duration of a fragment, but SHOULD NOT exceed maximum
-   * buffering time */
   GST_DEBUG_OBJECT (demux, "download loop %i", demux->end_of_manifest);
-  target_buffering_time =
-      demux->min_buffering_time +
-      gst_mpd_client_get_next_fragment_duration (demux->client);
-  if (demux->max_buffering_time > target_buffering_time)
-    target_buffering_time = demux->max_buffering_time;
-  if (!demux->end_of_manifest
-      && gst_dash_demux_get_buffering_time (demux) < target_buffering_time) {
-    if (GST_STATE (demux) != GST_STATE_PLAYING) {
-      /* Signal our buffering status (this will eventually restart the
-       * pipeline when we have reached 100 %) */
-      gst_element_post_message (GST_ELEMENT (demux),
-          gst_message_new_buffering (GST_OBJECT (demux),
-              100 * gst_dash_demux_get_buffering_ratio (demux)));
-    }
 
-    /* try to switch to another set of representations if needed */
-    gst_dash_demux_select_representations (demux,
-        demux->bandwidth_usage * demux->dnl_rate *
-        gst_dash_demux_get_buffering_ratio (demux));
-
-    /* fetch the next fragment */
-    while (!gst_dash_demux_get_next_fragment_set (demux)) {
-      if (demux->end_of_period) {
-        GST_INFO_OBJECT (demux, "Reached the end of the Period");
-        /* setup video, audio and subtitle streams, starting from the next Period */
-        if (!gst_mpd_client_set_period_index (demux->client,
-                gst_mpd_client_get_period_index (demux->client) + 1)
-            || !gst_dash_demux_setup_all_streams (demux)) {
-          GST_INFO_OBJECT (demux, "Reached the end of the manifest file");
-          demux->end_of_manifest = TRUE;
-          if (GST_STATE (demux) != GST_STATE_PLAYING) {
-            /* Restart the pipeline regardless of the current buffering level */
-            gst_element_post_message (GST_ELEMENT (demux),
-                gst_message_new_buffering (GST_OBJECT (demux), 100));
-          }
-          gst_task_start (demux->stream_task);
-          goto end_of_manifest;
-        }
-        /* start playing from the first segment of the new period */
-        gst_mpd_client_set_segment_index_for_all_streams (demux->client, 0);
-        demux->end_of_period = FALSE;
-      } else if (!demux->cancelled) {
-        demux->client->update_failed_count++;
-        if (demux->client->update_failed_count < DEFAULT_FAILED_COUNT) {
-          GST_WARNING_OBJECT (demux, "Could not fetch the next fragment");
-          goto quit;
-        } else {
-          goto error_downloading;
-        }
-      } else {
+  /* try to switch to another set of representations if needed */
+  gst_dash_demux_select_representations (demux,
+      demux->bandwidth_usage * demux->dnl_rate);
+
+  /* fetch the next fragment */
+  while (!gst_dash_demux_get_next_fragment_set (demux)) {
+    if (demux->end_of_period) {
+      GST_INFO_OBJECT (demux, "Reached the end of the Period");
+      /* setup video, audio and subtitle streams, starting from the next Period */
+      if (!gst_mpd_client_set_period_index (demux->client,
+              gst_mpd_client_get_period_index (demux->client) + 1)
+          || !gst_dash_demux_setup_all_streams (demux)) {
+        GST_INFO_OBJECT (demux, "Reached the end of the manifest file");
+        demux->end_of_manifest = TRUE;
+        gst_task_start (demux->stream_task);
+        goto end_of_manifest;
+      }
+      /* start playing from the first segment of the new period */
+      gst_mpd_client_set_segment_index_for_all_streams (demux->client, 0);
+      demux->end_of_period = FALSE;
+    } else if (!demux->cancelled) {
+      demux->client->update_failed_count++;
+      if (demux->client->update_failed_count < DEFAULT_FAILED_COUNT) {
+        GST_WARNING_OBJECT (demux, "Could not fetch the next fragment");
         goto quit;
+      } else {
+        goto error_downloading;
       }
+    } else {
+      goto quit;
     }
-    GST_INFO_OBJECT (demux, "Internal buffering : %" PRIu64 " s",
-        gst_dash_demux_get_buffering_time (demux) / GST_SECOND);
-    demux->client->update_failed_count = 0;
-  } else {
-    /* schedule the next download in 100 ms */
-    g_get_current_time (&demux->next_download);
-    g_time_val_add (&demux->next_download, 100000);
   }
+  GST_INFO_OBJECT (demux, "Internal buffering : %" PRIu64 " s",
+      gst_dash_demux_get_buffering_time (demux) / GST_SECOND);
+  demux->client->update_failed_count = 0;
 
 quit:
   {
@@ -1518,7 +1450,6 @@ gst_dash_demux_resume_stream_task (GstDashDemux * demux)
 static void
 gst_dash_demux_resume_download_task (GstDashDemux * demux)
 {
-  g_get_current_time (&demux->next_download);
   gst_task_start (demux->download_task);
 }
 

diff --git a/ext/dash/gstdashdemux.h b/ext/dash/gstdashdemux.h
index 3946eb0..384e25c 100644 (file)
--- a/ext/dash/gstdashdemux.h
+++ b/ext/dash/gstdashdemux.h
@@ -103,7 +103,6 @@ struct _GstDashDemux
   gboolean end_of_manifest;
 
   /* Properties */
-  GstClockTime min_buffering_time;      /* Minimum buffering time accumulated before playback */
   GstClockTime max_buffering_time;      /* Maximum buffering time accumulated during playback */
   gfloat bandwidth_usage;       /* Percentage of the available bandwidth to use       */
   guint64 max_bitrate;          /* max of bitrate supported by target decoder         */
@@ -118,7 +117,6 @@ struct _GstDashDemux
   GStaticRecMutex download_lock;
   gboolean cancelled;
   GMutex *download_timed_lock;
-  GTimeVal next_download;       /* Time of the next download */
 
   /* Manifest update */
   GstClockTime last_manifest_update;