multiqueue: Handle use-interleave latency live pipelines

Due to the dynamic nature of multiqueue, when `use-interleave` is used we can't
report a maximum tolerated latency (when queried) since it is calculated
dynamically.

When in such live pipelines, we need to make sure multiqueue can handle the
lowest global latency (provided by this event). Failure to do that would
result in not providing enough buffering for a realtime pipeline.

Fixes #1732

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3810>

diff --git a/subprojects/gstreamer/plugins/elements/gstmultiqueue.c b/subprojects/gstreamer/plugins/elements/gstmultiqueue.c
index cf4edc8..b65b51b 100644 (file)
--- a/subprojects/gstreamer/plugins/elements/gstmultiqueue.c
+++ b/subprojects/gstreamer/plugins/elements/gstmultiqueue.c
@@ -2964,6 +2964,34 @@ gst_multi_queue_src_event (GstPad * pad, GstObject * parent, GstEvent * event)
   }
 
   switch (GST_EVENT_TYPE (event)) {
+    case GST_EVENT_LATENCY:
+    {
+      GstClockTime latency = GST_CLOCK_TIME_NONE;
+      gst_event_parse_latency (event, &latency);
+      if (GST_CLOCK_TIME_IS_VALID (latency)) {
+        GST_MULTI_QUEUE_MUTEX_LOCK (mq);
+        if (latency > mq->min_interleave_time) {
+          /* Due to the dynamic nature of multiqueue, whe `use-interleave` is
+           * used we can't report a maximum tolerated latency (when queried)
+           * since it is calculated dynamically.
+           *
+           * When in such live pipelines, we need to make sure multiqueue can
+           * handle the lowest global latency (provided by this event). Failure
+           * to do that would result in not providing enough buffering for a
+           * realtime pipeline.
+           */
+          GST_DEBUG_OBJECT (mq,
+              "Raising minimum interleave time to %" GST_TIME_FORMAT,
+              GST_TIME_ARGS (latency));
+          mq->min_interleave_time = latency;
+          if (mq->use_interleave)
+            calculate_interleave (mq, NULL);
+        }
+        GST_MULTI_QUEUE_MUTEX_UNLOCK (mq);
+      }
+      ret = gst_pad_push_event (sinkpad, event);
+    }
+      break;
     case GST_EVENT_RECONFIGURE:
       GST_MULTI_QUEUE_MUTEX_LOCK (mq);
       if (sq->srcresult == GST_FLOW_NOT_LINKED) {