core: pipeline: add gst_pipeline_get_configured_latency()

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/4472>

girs/Gst-1.0.gir

@@ -32854,6 +32854,23 @@ clock, even if the pipeline is not in the PLAYING state.</doc>
           </instance-parameter>
         </parameters>
       </method>
+      <method name="get_configured_latency" c:identifier="gst_pipeline_get_configured_latency" version="1.24">
+        <doc xml:space="preserve" filename="../subprojects/gstreamer/gst/gstpipeline.c">Return the configured latency on @pipeline.</doc>
+        <source-position filename="../subprojects/gstreamer/gst/gstpipeline.h"/>
+        <return-value transfer-ownership="none">
+          <doc xml:space="preserve" filename="../subprojects/gstreamer/gst/gstpipeline.c">@pipeline configured latency, or %GST_CLOCK_TIME_NONE if none has been configured
+because @pipeline did not reach the PLAYING state yet.
+
+MT safe.</doc>
+          <type name="ClockTime" c:type="GstClockTime"/>
+        </return-value>
+        <parameters>
+          <instance-parameter name="pipeline" transfer-ownership="none">
+            <doc xml:space="preserve" filename="../subprojects/gstreamer/gst/gstpipeline.c">a #GstPipeline</doc>
+            <type name="Pipeline" c:type="GstPipeline*"/>
+          </instance-parameter>
+        </parameters>
+      </method>
       <method name="get_delay" c:identifier="gst_pipeline_get_delay">
         <doc xml:space="preserve" filename="../subprojects/gstreamer/gst/gstpipeline.c">Get the configured delay (see gst_pipeline_set_delay()).</doc>
         <source-position filename="../subprojects/gstreamer/gst/gstpipeline.h"/>

subprojects/gstreamer/gst/gstpipeline.c

@@ -114,6 +114,7 @@ struct _GstPipelinePrivate
   /* with LOCK */
   gboolean auto_flush_bus;
   gboolean is_live;
+  GstClockTime min_latency;
 
   /* when we need to update stream_time or clock when going back to
    * PLAYING*/
@@ -234,6 +235,7 @@ gst_pipeline_init (GstPipeline * pipeline)
   pipeline->priv->latency = DEFAULT_LATENCY;
 
   pipeline->priv->is_live = FALSE;
+  pipeline->priv->min_latency = GST_CLOCK_TIME_NONE;
 
   /* create and set a default bus */
   bus = gst_bus_new ();
@@ -521,6 +523,7 @@ gst_pipeline_change_state (GstElement * element, GstStateChange transition)
     case GST_STATE_CHANGE_PAUSED_TO_READY:
       GST_OBJECT_LOCK (element);
       pipeline->priv->is_live = FALSE;
+      pipeline->priv->min_latency = GST_CLOCK_TIME_NONE;
       GST_OBJECT_UNLOCK (element);
       reset_start_time (pipeline, 0);
       break;
@@ -701,6 +704,10 @@ gst_pipeline_do_latency (GstBin * bin)
 
     gst_query_parse_latency (query, &live, &min_latency, &max_latency);
 
+    GST_OBJECT_LOCK (pipeline);
+    pipeline->priv->min_latency = min_latency;
+    GST_OBJECT_UNLOCK (pipeline);
+
     GST_DEBUG_OBJECT (pipeline,
         "got min latency %" GST_TIME_FORMAT ", max latency %"
         GST_TIME_FORMAT ", live %d", GST_TIME_ARGS (min_latency),
@@ -1200,3 +1207,28 @@ gst_pipeline_is_live (GstPipeline * pipeline)
 
   return is_live;
 }
+
+/**
+ * gst_pipeline_get_configured_latency:
+ * @pipeline: a #GstPipeline
+ *
+ * Return the configured latency on @pipeline.
+ *
+ * Returns: @pipeline configured latency, or %GST_CLOCK_TIME_NONE if none has been configured
+ * because @pipeline did not reach the PLAYING state yet.
+ *
+ * MT safe.
+ *
+ * Since: 1.24
+ */
+GstClockTime
+gst_pipeline_get_configured_latency (GstPipeline * pipeline)
+{
+  GstClockTime min_latency;
+
+  GST_OBJECT_LOCK (pipeline);
+  min_latency = pipeline->priv->min_latency;
+  GST_OBJECT_UNLOCK (pipeline);
+
+  return min_latency;
+}

subprojects/gstreamer/gst/gstpipeline.h

@@ -133,6 +133,9 @@ gboolean        gst_pipeline_get_auto_flush_bus (GstPipeline *pipeline);
 GST_API
 gboolean        gst_pipeline_is_live            (GstPipeline *pipeline);
 
+GST_API
+GstClockTime    gst_pipeline_get_configured_latency    (GstPipeline * pipeline);
+
 G_DEFINE_AUTOPTR_CLEANUP_FUNC(GstPipeline, gst_object_unref)
 
 G_END_DECLS