decklink: Implement latency query in sources and remember selected mode

sys/decklink/gstdecklink.h

@@ -121,6 +121,10 @@ struct _GstDecklinkOutput {
   /* Everything below protected by mutex */
   GMutex lock;
 
+  /* Set by the video source */
+  /* Configured mode or NULL */
+  const GstDecklinkMode *mode;
+
   /* Set by the audio sink */
   GstClock *audio_clock;
 
@@ -141,6 +145,8 @@ struct _GstDecklinkInput {
 
   /* Set by the video source */
   void (*got_video_frame) (GstElement *videosrc, IDeckLinkVideoInputFrame * frame, GstClockTime capture_time);
+  /* Configured mode or NULL */
+  const GstDecklinkMode *mode;
 
   /* Set by the audio source */
   void (*got_audio_packet) (GstElement *videosrc, IDeckLinkAudioInputPacket * packet, GstClockTime capture_time);

sys/decklink/gstdecklinkaudiosink.cpp

@@ -498,8 +498,11 @@ gst_decklink_audio_sink_init (GstDecklinkAudioSink * self)
 {
   self->device_number = 0;
 
-  // 25ms latency time seems to be needed at least,
+  // 25.000ms latency time seems to be needed at least,
   // everything below can cause drop-outs
+  // TODO: This is probably related to the video mode that
+  // is selected, but not directly it seems. Choosing the
+  // duration of a frame does not work.
   GST_AUDIO_BASE_SINK_CAST (self)->latency_time = 25000;
 }
 

sys/decklink/gstdecklinkaudiosrc.cpp

@@ -60,6 +60,8 @@ static GstCaps *gst_decklink_audio_src_get_caps (GstBaseSrc * bsrc,
     GstCaps * filter);
 static gboolean gst_decklink_audio_src_unlock (GstBaseSrc * bsrc);
 static gboolean gst_decklink_audio_src_unlock_stop (GstBaseSrc * bsrc);
+static gboolean gst_decklink_audio_src_query (GstBaseSrc * bsrc,
+    GstQuery * query);
 
 static GstFlowReturn gst_decklink_audio_src_create (GstPushSrc * psrc,
     GstBuffer ** buffer);
@@ -89,6 +91,7 @@ gst_decklink_audio_src_class_init (GstDecklinkAudioSrcClass * klass)
 
   basesrc_class->get_caps = GST_DEBUG_FUNCPTR (gst_decklink_audio_src_get_caps);
   basesrc_class->set_caps = GST_DEBUG_FUNCPTR (gst_decklink_audio_src_set_caps);
+  basesrc_class->query = GST_DEBUG_FUNCPTR (gst_decklink_audio_src_query);
   basesrc_class->unlock = GST_DEBUG_FUNCPTR (gst_decklink_audio_src_unlock);
   basesrc_class->unlock_stop =
       GST_DEBUG_FUNCPTR (gst_decklink_audio_src_unlock_stop);
@@ -333,6 +336,44 @@ gst_decklink_audio_src_create (GstPushSrc * bsrc, GstBuffer ** buffer)
   return flow_ret;
 }
 
+static gboolean
+gst_decklink_audio_src_query (GstBaseSrc * bsrc, GstQuery * query)
+{
+  GstDecklinkAudioSrc *self = GST_DECKLINK_AUDIO_SRC_CAST (bsrc);
+  gboolean ret = TRUE;
+
+  switch (GST_QUERY_TYPE (query)) {
+    case GST_QUERY_LATENCY:{
+      if (self->input) {
+        g_mutex_lock (&self->input->lock);
+        if (self->input->mode) {
+          GstClockTime min, max;
+
+          min =
+              gst_util_uint64_scale_ceil (GST_MSECOND, self->input->mode->fps_d,
+              self->input->mode->fps_n);
+          max = min;
+
+          gst_query_set_latency (query, TRUE, min, max);
+          ret = TRUE;
+        } else {
+          ret = FALSE;
+        }
+        g_mutex_unlock (&self->input->lock);
+      } else {
+        ret = FALSE;
+      }
+
+      break;
+    }
+    default:
+      ret = GST_BASE_SRC_CLASS (parent_class)->query (bsrc, query);
+      break;
+  }
+
+  return ret;
+}
+
 static gboolean
 gst_decklink_audio_src_unlock (GstBaseSrc * bsrc)
 {

sys/decklink/gstdecklinkvideosink.cpp

@@ -313,6 +313,10 @@ gst_decklink_video_sink_open (GstBaseSink * bsink)
     return FALSE;
   }
 
+  g_mutex_lock (&self->output->lock);
+  self->output->mode = mode;
+  g_mutex_unlock (&self->output->lock);
+
   caps = gst_decklink_mode_get_caps (self->mode);
   gst_video_info_from_caps (&self->info, caps);
   gst_caps_unref (caps);
@@ -328,6 +332,10 @@ gst_decklink_video_sink_close (GstBaseSink * bsink)
   GST_DEBUG_OBJECT (self, "Stopping");
 
   if (self->output) {
+    g_mutex_lock (&self->output->lock);
+    self->output->mode = NULL;
+    g_mutex_unlock (&self->output->lock);
+
     self->output->output->DisableVideoOutput ();
     gst_decklink_release_nth_output (self->device_number,
         GST_ELEMENT_CAST (self), FALSE);

sys/decklink/gstdecklinkvideosrc.cpp

@@ -48,6 +48,8 @@ static GstClock *gst_decklink_video_src_provide_clock (GstElement * element);
 
 static GstCaps *gst_decklink_video_src_get_caps (GstBaseSrc * bsrc,
     GstCaps * filter);
+static gboolean gst_decklink_video_src_query (GstBaseSrc * bsrc,
+    GstQuery * query);
 static gboolean gst_decklink_video_src_unlock (GstBaseSrc * bsrc);
 static gboolean gst_decklink_video_src_unlock_stop (GstBaseSrc * bsrc);
 
@@ -79,6 +81,7 @@ gst_decklink_video_src_class_init (GstDecklinkVideoSrcClass * klass)
       GST_DEBUG_FUNCPTR (gst_decklink_video_src_provide_clock);
 
   basesrc_class->get_caps = GST_DEBUG_FUNCPTR (gst_decklink_video_src_get_caps);
+  basesrc_class->query = GST_DEBUG_FUNCPTR (gst_decklink_video_src_query);
   basesrc_class->unlock = GST_DEBUG_FUNCPTR (gst_decklink_video_src_unlock);
   basesrc_class->unlock_stop =
       GST_DEBUG_FUNCPTR (gst_decklink_video_src_unlock_stop);
@@ -197,7 +200,8 @@ gst_decklink_video_src_got_frame (GstElement * element,
 {
   GstDecklinkVideoSrc *self = GST_DECKLINK_VIDEO_SRC_CAST (element);
 
-  GST_LOG_OBJECT (self, "Got video frame at %" GST_TIME_FORMAT, GST_TIME_ARGS (capture_time));
+  GST_LOG_OBJECT (self, "Got video frame at %" GST_TIME_FORMAT,
+      GST_TIME_ARGS (capture_time));
 
   g_mutex_lock (&self->lock);
   if (!self->flushing) {
@@ -276,6 +280,40 @@ gst_decklink_video_src_create (GstPushSrc * bsrc, GstBuffer ** buffer)
   return flow_ret;
 }
 
+static gboolean
+gst_decklink_video_src_query (GstBaseSrc * bsrc, GstQuery * query)
+{
+  GstDecklinkVideoSrc *self = GST_DECKLINK_VIDEO_SRC_CAST (bsrc);
+  gboolean ret = TRUE;
+
+  switch (GST_QUERY_TYPE (query)) {
+    case GST_QUERY_LATENCY:{
+      if (self->input) {
+        GstClockTime min, max;
+        const GstDecklinkMode *mode;
+
+        mode = gst_decklink_get_mode (self->mode);
+
+        min =
+            gst_util_uint64_scale_ceil (GST_MSECOND, mode->fps_d, mode->fps_n);
+        max = min;
+
+        gst_query_set_latency (query, TRUE, min, max);
+        ret = TRUE;
+      } else {
+        ret = FALSE;
+      }
+
+      break;
+    }
+    default:
+      ret = GST_BASE_SRC_CLASS (parent_class)->query (bsrc, query);
+      break;
+  }
+
+  return ret;
+}
+
 static gboolean
 gst_decklink_video_src_unlock (GstBaseSrc * bsrc)
 {
@@ -331,6 +369,7 @@ gst_decklink_video_src_open (GstDecklinkVideoSrc * self)
   }
 
   g_mutex_lock (&self->input->lock);
+  self->input->mode = mode;
   self->input->got_video_frame = gst_decklink_video_src_got_frame;
   g_mutex_unlock (&self->input->lock);
 
@@ -350,6 +389,7 @@ gst_decklink_video_src_close (GstDecklinkVideoSrc * self)
   if (self->input) {
     g_mutex_lock (&self->input->lock);
     self->input->got_video_frame = NULL;
+    self->input->mode = NULL;
     g_mutex_unlock (&self->input->lock);
 
     self->input->input->DisableVideoInput ();