rtpsession: fix rb blocks disappearing after the first rtcp cycle with multiple senders

Previously, when the session had multiple internal sender SSRCs, it would
issue SR reports with RB blocks only on the first RTCP timeout and afterwards
SR reports would be sent empty. This was because the "generation" number
in RTPSource would increase more than once during the same cycle and afterwards
it would always be greater than the session's generation, which would cause
it to be skipped from being included in RBs.

This commit fixes this problem by:
1) Increasing the RTPSource generation only at the end of each cycle,
which essentially fixes the problem but only when the internal senders
are less than GST_RTCP_MAX_RB_COUNT.
2) Keeping for each RTPSource a set of SSRCs which stores which SSRC's
SR the given RTPSource has been reported in, which also fixes the problem
when the internal senders are more than GST_RTCP_MAX_RB_COUNT. This is
necessary because of the fact that any RTPSource is marked as reported
in itself's SR and makes it impossible to know if it has been reported
in other SRs too or not, and which.

gst/rtpmanager/rtpsession.c

@@ -2975,15 +2975,21 @@ session_report_blocks (const gchar * key, RTPSource * source, ReportData * data)
     return;
   }
 
-  /* only report about other sender */
-  if (source == data->source)
-    goto reported;
+  if (g_hash_table_contains (source->reported_in_sr_of,
+          GUINT_TO_POINTER (data->source->ssrc))) {
+    GST_DEBUG ("source %08x already reported in this generation", source->ssrc);
+    return;
+  }
 
   if (gst_rtcp_packet_get_rb_count (packet) == GST_RTCP_MAX_RB_COUNT) {
     GST_DEBUG ("max RB count reached");
     return;
   }
 
+  /* only report about other sender */
+  if (source == data->source)
+    goto reported;
+
   if (!RTP_SOURCE_IS_SENDER (source)) {
     GST_DEBUG ("source %08x not sender", source->ssrc);
     goto reported;
@@ -3009,14 +3015,8 @@ session_report_blocks (const gchar * key, RTPSource * source, ReportData * data)
       exthighestseq, jitter, lsr, dlsr);
 
 reported:
-  /* source is reported, move to next generation */
-  source->generation = sess->generation + 1;
-
-  /* if we reported all sources in this generation, move to next */
-  if (--data->num_to_report == 0) {
-    sess->generation++;
-    GST_DEBUG ("all reported, generation now %u", sess->generation);
-  }
+  g_hash_table_add (source->reported_in_sr_of,
+      GUINT_TO_POINTER (data->source->ssrc));
 }
 
 /* construct FIR */
@@ -3534,6 +3534,28 @@ generate_rtcp (const gchar * key, RTPSource * source, ReportData * data)
   g_queue_push_tail (&data->output, output);
 }
 
+static void
+update_generation (const gchar * key, RTPSource * source, ReportData * data)
+{
+  RTPSession *sess = data->sess;
+
+  if (g_hash_table_size (source->reported_in_sr_of) >=
+      sess->stats.internal_sources) {
+    /* source is reported, move to next generation */
+    source->generation = sess->generation + 1;
+    g_hash_table_remove_all (source->reported_in_sr_of);
+
+    GST_LOG ("reported source %x, new generation: %d", source->ssrc,
+        source->generation);
+
+    /* if we reported all sources in this generation, move to next */
+    if (--data->num_to_report == 0) {
+      sess->generation++;
+      GST_DEBUG ("all reported, generation now %u", sess->generation);
+    }
+  }
+}
+
 /**
  * rtp_session_on_timeout:
  * @sess: an #RTPSession
@@ -3621,6 +3643,10 @@ rtp_session_on_timeout (RTPSession * sess, GstClockTime current_time,
   g_hash_table_foreach (sess->ssrcs[sess->mask_idx],
       (GHFunc) generate_rtcp, &data);
 
+  /* update the generation for all the sources that have been reported */
+  g_hash_table_foreach (sess->ssrcs[sess->mask_idx],
+      (GHFunc) update_generation, &data);
+
   /* we keep track of the last report time in order to timeout inactive
    * receivers or senders */
   if (!data.is_early && !data.may_suppress)

gst/rtpmanager/rtpsource.c

@@ -224,6 +224,7 @@ rtp_source_reset (RTPSource * src)
     g_free (src->bye_reason);
   src->bye_reason = NULL;
   src->sent_bye = FALSE;
+  g_hash_table_remove_all (src->reported_in_sr_of);
 
   src->stats.cycles = -1;
   src->stats.jitter = 0;
@@ -261,6 +262,8 @@ rtp_source_init (RTPSource * src)
   src->retained_feedback = g_queue_new ();
   src->nacks = g_array_new (FALSE, FALSE, sizeof (guint32));
 
+  src->reported_in_sr_of = g_hash_table_new (g_direct_hash, g_direct_equal);
+
   rtp_source_reset (src);
 }
 
@@ -304,6 +307,8 @@ rtp_source_finalize (GObject * object)
   if (src->rtcp_from)
     g_object_unref (src->rtcp_from);
 
+  g_hash_table_unref (src->reported_in_sr_of);
+
   G_OBJECT_CLASS (rtp_source_parent_class)->finalize (object);
 }
 

gst/rtpmanager/rtpsource.h

@@ -136,6 +136,8 @@ struct _RTPSource {
   guint32       ssrc;
 
   guint16       generation;
+  GHashTable    *reported_in_sr_of;     /* set of SSRCs */
+
   guint         probation;
   guint         curr_probation;
   gboolean      validated;