ui/handler, encoder: Allow overriding lag in frames

The lag in frames is not dictated by the number of threads being used by some encoders. At least for hardware encoders, the expected frame lag in real time encoding is 1 + the number of bframes

source/encoder.cpp

@@ -878,6 +878,9 @@ bool obsffmpeg::encoder::update(obs_data_t* settings)
 		                       nullptr, "=", ";");
 	}
 
+	if (_handler)
+		_handler->override_lag_in_frames(_lag_in_frames, settings, _codec, _context);
+
 	// Handler Logging
 	if (_handler)
 		_handler->log_options(settings, _codec, _context);
@@ -1102,7 +1105,7 @@ bool obsffmpeg::encoder::encode_avframe(std::shared_ptr<AVFrame> frame, encoder_
 
 	bool sent_frame  = false;
 	bool recv_packet = false;
-	bool should_lag  = (_lag_in_frames - _count_send_frames) <= 0;
+	bool should_lag  = (_count_send_frames >= _lag_in_frames);
 
 	auto loop_begin = std::chrono::high_resolution_clock::now();
 	auto loop_end   = loop_begin + std::chrono::milliseconds(50);

source/encoder.hpp

@@ -94,8 +94,8 @@ namespace obsffmpeg {
 		ffmpeg::swscale _swscale;
 		AVPacket        _current_packet;
 
-		int64_t _lag_in_frames;
+		size_t _lag_in_frames;
-		int64_t _count_send_frames;
+		size_t _count_send_frames;
 
 		// Extra Data
 		bool                 _have_first_frame;

source/ui/handler.cpp

@@ -29,6 +29,10 @@ void obsffmpeg::ui::handler::override_colorformat(AVPixelFormat& target_format,
                                                   const AVCodec* codec, AVCodecContext* context)
 {}
 
+void obsffmpeg::ui::handler::override_lag_in_frames(size_t& lag, obs_data_t* settings, const AVCodec* codec,
+                                                    AVCodecContext* context)
+{}
+
 void obsffmpeg::ui::handler::get_defaults(obs_data_t* settings, const AVCodec* codec, AVCodecContext* context) {}
 
 void obsffmpeg::ui::handler::get_properties(obs_properties_t* props, const AVCodec* codec, AVCodecContext* context) {}

source/ui/handler.hpp

@@ -47,6 +47,9 @@ namespace obsffmpeg {
 			virtual void override_colorformat(AVPixelFormat& target_format, obs_data_t* settings,
 			                                  const AVCodec* codec, AVCodecContext* context);
 
+			virtual void override_lag_in_frames(size_t& lag, obs_data_t* settings, const AVCodec* codec,
+			                                       AVCodecContext* context);
+
 			virtual void get_defaults(obs_data_t* settings, const AVCodec* codec, AVCodecContext* context);
 
 			virtual void get_properties(obs_properties_t* props, const AVCodec* codec,