From 8e75c37ce4e5137143f414ae9a4893f26fd899f9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sebastian=20Dr=C3=B6ge?= <sebastian@centricular.com>
Date: Wed, 18 Aug 2021 17:36:46 +0300
Subject: [PATCH] Add signal property to ajasrc to allow checking/notify about
 signal availability at any time

---
 gstajasrc.cpp | 37 +++++++++++++++++++++++++++++++++++++
 gstajasrc.h   |  1 +
 2 files changed, 38 insertions(+)

diff --git a/gstajasrc.cpp b/gstajasrc.cpp
index 8971f50976..46b8ac4db1 100644
--- a/gstajasrc.cpp
+++ b/gstajasrc.cpp
@@ -57,6 +57,7 @@ enum {
   PROP_REFERENCE_SOURCE,
   PROP_QUEUE_SIZE,
   PROP_CAPTURE_CPU_CORE,
+  PROP_SIGNAL,
 };
 
 typedef enum {
@@ -205,6 +206,13 @@ static void gst_aja_src_class_init(GstAjaSrcClass *klass) {
           (GParamFlags)(G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS |
                         G_PARAM_CONSTRUCT)));
 
+  g_object_class_install_property(
+      gobject_class, PROP_SIGNAL,
+      g_param_spec_boolean(
+          "signal", "Input signal available",
+          "True if there is a valid input signal available", FALSE,
+          (GParamFlags)(G_PARAM_READABLE | G_PARAM_STATIC_STRINGS)));
+
   element_class->change_state = GST_DEBUG_FUNCPTR(gst_aja_src_change_state);
 
   basesrc_class->get_caps = GST_DEBUG_FUNCPTR(gst_aja_src_get_caps);
@@ -335,6 +343,9 @@ void gst_aja_src_get_property(GObject *object, guint property_id, GValue *value,
     case PROP_CAPTURE_CPU_CORE:
       g_value_set_uint(value, self->capture_cpu_core);
       break;
+    case PROP_SIGNAL:
+      g_value_set_boolean(value, self->signal);
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID(object, property_id, pspec);
       break;
@@ -1144,6 +1155,7 @@ static gboolean gst_aja_src_start(GstAjaSrc *self) {
   GST_DEBUG_OBJECT(self, "Starting");
 
   self->video_format = NTV2_FORMAT_UNKNOWN;
+  self->signal = FALSE;
 
   self->capture_thread = new AJAThread();
   self->capture_thread->Attach(capture_thread_func, self);
@@ -1209,6 +1221,11 @@ static gboolean gst_aja_src_stop(GstAjaSrc *self) {
 
   self->video_format = NTV2_FORMAT_UNKNOWN;
 
+  if (self->signal) {
+    self->signal = FALSE;
+    g_object_notify(G_OBJECT(self), "signal");
+  }
+
   GST_DEBUG_OBJECT(self, "Stopped");
 
   return TRUE;
@@ -1676,6 +1693,10 @@ restart:
                               ("No input source was detected"));
           have_signal = FALSE;
         }
+        if (self->signal) {
+          self->signal = FALSE;
+          g_object_notify(G_OBJECT(self), "signal");
+        }
         self->device->device->WaitForInputVerticalInterrupt(self->channel);
         continue;
       }
@@ -1726,6 +1747,10 @@ restart:
                             ("No input source was detected"));
         have_signal = FALSE;
       }
+      if (self->signal) {
+        self->signal = FALSE;
+        g_object_notify(G_OBJECT(self), "signal");
+      }
       self->device->device->WaitForInputVerticalInterrupt(self->channel);
       g_mutex_lock(&self->queue_lock);
       continue;
@@ -1757,6 +1782,10 @@ restart:
                              current_string.c_str()));
         have_signal = FALSE;
       }
+      if (self->signal) {
+        self->signal = FALSE;
+        g_object_notify(G_OBJECT(self), "signal");
+      }
       self->device->device->WaitForInputVerticalInterrupt(self->channel);
       g_mutex_lock(&self->queue_lock);
       continue;
@@ -1819,6 +1848,10 @@ restart:
                          ("Signal recovered"), ("Input source detected"));
         have_signal = TRUE;
       }
+      if (!self->signal) {
+        self->signal = TRUE;
+        g_object_notify(G_OBJECT(self), "signal");
+      }
 
       iterations_without_frame = 0;
 
@@ -1994,6 +2027,10 @@ restart:
                               ("Signal lost"), ("No frames captured"));
           have_signal = FALSE;
         }
+        if (self->signal) {
+          self->signal = FALSE;
+          g_object_notify(G_OBJECT(self), "signal");
+        }
       }
 
       self->device->device->WaitForInputVerticalInterrupt(self->channel);
diff --git a/gstajasrc.h b/gstajasrc.h
index dcfeeff1b1..4cbddbac22 100644
--- a/gstajasrc.h
+++ b/gstajasrc.h
@@ -71,6 +71,7 @@ struct _GstAjaSrc {
   GstAjaReferenceSource reference_source;
   guint queue_size;
   guint capture_cpu_core;
+  gboolean signal;
 
   NTV2AudioSystem audio_system;
   NTV2VideoFormat video_format;