libobs: Add video tick callback functions

Allows the ability to have a callback invoked every time video ticks.
Particularly useful for scripting.

libobs/obs-internal.h

@@ -44,6 +44,11 @@ static inline int64_t packet_dts_usec(struct encoder_packet *packet)
 	return packet->dts * MICROSECOND_DEN / packet->timebase_den;
 }
 
+struct tick_callback {
+	void (*tick)(void *param, float seconds);
+	void *param;
+};
+
 struct draw_callback {
 	void (*draw)(void *param, uint32_t cx, uint32_t cy);
 	void *param;
@@ -319,6 +324,7 @@ struct obs_core_data {
 	pthread_mutex_t                 audio_sources_mutex;
 	pthread_mutex_t                 draw_callbacks_mutex;
 	DARRAY(struct draw_callback)    draw_callbacks;
+	DARRAY(struct tick_callback)    tick_callbacks;
 
 	struct obs_view                 main_view;
 

libobs/obs-video.c

@@ -38,9 +38,24 @@ static uint64_t tick_sources(uint64_t cur_time, uint64_t last_time)
 	delta_time = cur_time - last_time;
 	seconds = (float)((double)delta_time / 1000000000.0);
 
-	pthread_mutex_lock(&data->sources_mutex);
+	/* ------------------------------------- */
+	/* call tick callbacks                   */
+
+	pthread_mutex_lock(&obs->data.draw_callbacks_mutex);
+
+	for (size_t i = obs->data.tick_callbacks.num; i > 0; i--) {
+		struct tick_callback *callback;
+		callback = obs->data.tick_callbacks.array + (i - 1);
+		callback->tick(callback->param, seconds);
+	}
 
+	pthread_mutex_unlock(&obs->data.draw_callbacks_mutex);
+
+	/* ------------------------------------- */
 	/* call the tick function of each source */
+
+	pthread_mutex_lock(&data->sources_mutex);
+
 	source = data->first_source;
 	while (source) {
 		obs_source_video_tick(source, seconds);
@@ -111,9 +126,9 @@ static inline void render_main_texture(struct obs_core_video *video,
 
 	pthread_mutex_lock(&obs->data.draw_callbacks_mutex);
 
-	for (size_t i = 0; i < obs->data.draw_callbacks.num; i++) {
+	for (size_t i = obs->data.draw_callbacks.num; i > 0; i--) {
 		struct draw_callback *callback;
-		callback = obs->data.draw_callbacks.array+i;
+		callback = obs->data.draw_callbacks.array + (i - 1);
 
 		callback->draw(callback->param,
 				video->base_width, video->base_height);

libobs/obs.c

@@ -560,7 +560,7 @@ static bool obs_init_data(void)
 		goto fail;
 	if (pthread_mutex_init(&data->services_mutex, &attr) != 0)
 		goto fail;
-	if (pthread_mutex_init(&obs->data.draw_callbacks_mutex, NULL) != 0)
+	if (pthread_mutex_init(&obs->data.draw_callbacks_mutex, &attr) != 0)
 		goto fail;
 	if (!obs_view_init(&data->main_view))
 		goto fail;
@@ -619,6 +619,7 @@ static void obs_free_data(void)
 	pthread_mutex_destroy(&data->services_mutex);
 	pthread_mutex_destroy(&data->draw_callbacks_mutex);
 	da_free(data->draw_callbacks);
+	da_free(data->tick_callbacks);
 }
 
 static const char *obs_signals[] = {
@@ -1977,6 +1978,34 @@ void obs_get_audio_monitoring_device(const char **name, const char **id)
 		*id = obs->audio.monitoring_device_id;
 }
 
+void obs_add_tick_callback(
+		void (*tick)(void *param, float seconds),
+		void *param)
+{
+	if (!obs)
+		return;
+
+	struct tick_callback data = {tick, param};
+
+	pthread_mutex_lock(&obs->data.draw_callbacks_mutex);
+	da_insert(obs->data.tick_callbacks, 0, &data);
+	pthread_mutex_unlock(&obs->data.draw_callbacks_mutex);
+}
+
+void obs_remove_tick_callback(
+		void (*tick)(void *param, float seconds),
+		void *param)
+{
+	if (!obs)
+		return;
+
+	struct tick_callback data = {tick, param};
+
+	pthread_mutex_lock(&obs->data.draw_callbacks_mutex);
+	da_erase_item(obs->data.tick_callbacks, &data);
+	pthread_mutex_unlock(&obs->data.draw_callbacks_mutex);
+}
+
 void obs_add_main_render_callback(
 		void (*draw)(void *param, uint32_t cx, uint32_t cy),
 		void *param)
@@ -1987,7 +2016,7 @@ void obs_add_main_render_callback(
 	struct draw_callback data = {draw, param};
 
 	pthread_mutex_lock(&obs->data.draw_callbacks_mutex);
-	da_push_back(obs->data.draw_callbacks, &data);
+	da_insert(obs->data.draw_callbacks, 0, &data);
 	pthread_mutex_unlock(&obs->data.draw_callbacks_mutex);
 }
 

libobs/obs.h

@@ -602,6 +602,13 @@ EXPORT void obs_enum_audio_monitoring_devices(obs_enum_audio_device_cb cb,
 EXPORT bool obs_set_audio_monitoring_device(const char *name, const char *id);
 EXPORT void obs_get_audio_monitoring_device(const char **name, const char **id);
 
+EXPORT void obs_add_tick_callback(
+		void (*tick)(void *param, float seconds),
+		void *param);
+EXPORT void obs_remove_tick_callback(
+		void (*tick)(void *param, float seconds),
+		void *param);
+
 EXPORT void obs_add_main_render_callback(
 		void (*draw)(void *param, uint32_t cx, uint32_t cy),
 		void *param);