obs_video_info: add unique id for sceneitem->canvas

Add an id field to obs_video_info so that when a new video_mix is created
within maybe_set_up_gpu_rescale() we can effectively reuse a canvas for
sceneItems that need to be rendered by an encoder. Resolves issue
where we saw a black screen during enhanced rendering.

Author: sandboxcoder

frontend/widgets/OBSBasic.cpp

@@ -1505,6 +1505,7 @@ int OBSBasic::ResetVideo()
 	ovi.adapter = config_get_uint(App()->GetUserConfig(), "Video", "AdapterIdx");
 	ovi.gpu_conversion = true;
 	ovi.scale_type = GetScaleType(activeConfiguration);
+	ovi.id = obs_create_video_info_id();
 
 	if (ovi.base_width < 32 || ovi.base_height < 32) {
 		ovi.base_width = 1920;

libobs/obs-encoder.c

@@ -274,6 +274,7 @@ static void maybe_set_up_gpu_rescale(struct obs_encoder *encoder)
 	ovi->scale_type = encoder->gpu_scale_type;
 
 	ovi->gpu_conversion = true;
+	ovi->id = current_mix->ovi->id; // Copy current id so obs_source->item->canvas render works
 
 	mix = obs_create_video_mix(ovi);
 	if (!mix)

libobs/obs-scene.c

@@ -1086,10 +1086,10 @@ static void scene_video_render(void *data, gs_effect_t *effect)
 	gs_blend_state_push();
 	gs_reset_blend_state();
 
+	size_t canvas_id = (obs_get_video_rendering_canvas() != NULL) ? obs_get_video_rendering_canvas()->id : -1;
 	item = scene->first_item;
 	while (item) {
-		if (obs_get_video_rendering_canvas() != item->canvas &&
-		    item->canvas != NULL) {
+		if (item->canvas != NULL && canvas_id != item->canvas->id) {
 			item = item->next;
 			continue;
 		}

libobs/obs.c

@@ -1967,10 +1967,21 @@ struct obs_video_info *obs_create_video_info()
 	ovi->scale_type = OBS_SCALE_BILINEAR;
 	ovi->adapter = 0;
 	ovi->gpu_conversion = true;
+	ovi->id = obs_create_video_info_id();
 
 	return ovi;
 }
 
+size_t obs_create_video_info_id()
+{
+	static size_t id = 0;
+	size_t currId = id++;
+	if (id == (size_t)-1) {
+		blog(LOG_ERROR, "obs_create_video_info_id wrap around detected!");
+	}
+	return currId;
+}
+
 size_t obs_get_video_info_count()
 {
 	return obs->video.canvases.num;

libobs/obs.h

@@ -224,6 +224,7 @@ struct obs_video_info {
 	enum video_range_type range;      /**< YUV range (if YUV) */
 
 	enum obs_scale_type scale_type; /**< How to scale if scaling */
+	size_t id;
 };
 
 /**
@@ -477,6 +478,7 @@ EXPORT bool obs_get_video_info_scene_item(obs_sceneitem_t *item,
 EXPORT int obs_remove_video_info(struct obs_video_info *ovi);
 /** Adds new video info to array of video info objects, need to be initialized */
 EXPORT struct obs_video_info *obs_create_video_info();
+EXPORT size_t obs_create_video_info_id();
 
 /**
  * Sets base audio output format/channels/samples/etc