aggregator: Keep at least two buffers in the queue in live mode

When in live mode, the queue needs to hold the currently processed
buffer and one more at least.

https://bugzilla.gnome.org/show_bug.cgi?id=754851

diff --git a/libs/gst/base/gstaggregator.c b/libs/gst/base/gstaggregator.c
index 9a0a55c..9d31649 100644 (file)
--- a/libs/gst/base/gstaggregator.c
+++ b/libs/gst/base/gstaggregator.c
@@ -216,6 +216,7 @@ struct _GstAggregatorPadPrivate
   gboolean pending_eos;
 
   GQueue buffers;
+  guint num_buffers;
   GstClockTime head_position;
   GstClockTime tail_position;
   GstClockTime head_time;
@@ -777,6 +778,7 @@ gst_aggregator_pad_set_flushing (GstAggregatorPad * aggpad,
     }
     item = next;
   }
+  aggpad->priv->num_buffers = 0;
 
   PAD_BROADCAST_EVENT (aggpad);
   PAD_UNLOCK (aggpad);
@@ -2041,7 +2043,7 @@ gst_aggregator_get_type (void)
   return type;
 }
 
-/* Must be called with PAD lock held */
+/* Must be called with SRC lock and PAD lock held */
 static gboolean
 gst_aggregator_pad_has_space (GstAggregator * self, GstAggregatorPad * aggpad)
 {
@@ -2049,6 +2051,11 @@ gst_aggregator_pad_has_space (GstAggregator * self, GstAggregatorPad * aggpad)
   if (g_queue_get_length (&aggpad->priv->buffers) == 0)
     return TRUE;
 
+  /* We also want at least two buffers, one is being processed and one is ready
+   * for the next iteration when we operate in live mode. */
+  if (self->priv->peer_latency_live && aggpad->priv->num_buffers < 2)
+    return TRUE;
+
   /* zero latency, if there is a buffer, it's full */
   if (self->priv->latency == 0)
     return FALSE;
@@ -2135,6 +2142,7 @@ gst_aggregator_pad_chain_internal (GstAggregator * self,
       else
         g_queue_push_tail (&aggpad->priv->buffers, actual_buf);
       apply_buffer (aggpad, actual_buf, head);
+      aggpad->priv->num_buffers++;
       actual_buf = buffer = NULL;
       SRC_BROADCAST (self);
       break;
@@ -2431,6 +2439,7 @@ gst_aggregator_pad_steal_buffer (GstAggregatorPad * pad)
 
   if (buffer) {
     apply_buffer (pad, buffer, FALSE);
+    pad->priv->num_buffers--;
     GST_TRACE_OBJECT (pad, "Consuming buffer");
     if (gst_aggregator_pad_queue_is_empty (pad) && pad->priv->pending_eos) {
       pad->priv->pending_eos = FALSE;