rpicam-vid: Update for camera sync algorithm

.gitignore

@@ -1,2 +1,3 @@
 build
 *~
+.vscode/

apps/rpicam_vid.cpp

@@ -117,7 +117,6 @@ static void event_loop(RPiCamEncoder &app)
 			app.StopEncoder();
 			return;
 		}
-
 		CompletedRequestPtr &completed_request = std::get<CompletedRequestPtr>(msg.payload);
 		app.EncodeBuffer(completed_request, app.VideoStream());
 		app.ShowPreview(completed_request, app.VideoStream());

core/rpicam_encoder.hpp

@@ -29,13 +29,30 @@ class RPiCamEncoder : public RPiCamApp
 		createEncoder();
 		encoder_->SetInputDoneCallback(std::bind(&RPiCamEncoder::encodeBufferDone, this, std::placeholders::_1));
 		encoder_->SetOutputReadyCallback(encode_output_ready_callback_);
+
+		// Set up the encode function to wait for synchronisation with another camera system,
+		// when this has been requested in the options.
+		VideoOptions const *options = GetOptions();
+		libcamera::ControlList cl;
+		if (options->sync == 0)
+			cl.set(libcamera::controls::rpi::SyncMode, libcamera::controls::rpi::SyncModeOff);
+		else if (options->sync == 1)
+			cl.set(libcamera::controls::rpi::SyncMode, libcamera::controls::rpi::SyncModeServer);
+		else if (options->sync == 2)
+			cl.set(libcamera::controls::rpi::SyncMode, libcamera::controls::rpi::SyncModeClient);
+		SetControls(cl);
 	}
 	// This is callback when the encoder gives you the encoded output data.
 	void SetEncodeOutputReadyCallback(EncodeOutputReadyCallback callback) { encode_output_ready_callback_ = callback; }
 	void SetMetadataReadyCallback(MetadataReadyCallback callback) { metadata_ready_callback_ = callback; }
 	void EncodeBuffer(CompletedRequestPtr &completed_request, Stream *stream)
 	{
 		assert(encoder_);
+
+		// If sync was enabled, and the SyncWait metadata is still "true" then we must skip this frame.
+		if (GetOptions()->sync && completed_request->metadata.get(controls::rpi::SyncWait).value_or(true))
+			return;
+
 		StreamInfo info = GetStreamInfo(stream);
 		FrameBuffer *buffer = completed_request->buffers[stream];
 		BufferReadSync r(this, buffer);

core/video_options.hpp

@@ -159,6 +159,8 @@ struct VideoOptions : public Options
 			 "Add a time offset (in microseconds if no units provided) to the audio stream, relative to the video stream. "
 			 "The offset value can be either positive or negative.")
 #endif
+			 ("sync", value<std::string>(&sync_)->default_value("off"),
+			  "Whether to synchronise with another camera. Use \"off\", \"server\" or \"client\".")
 			;
 		// clang-format on
 	}
@@ -191,6 +193,7 @@ struct VideoOptions : public Options
 	uint32_t segment;
 	size_t circular;
 	uint32_t frames;
+	uint32_t sync;
 
 	virtual bool Parse(int argc, char *argv[]) override
 	{
@@ -235,6 +238,15 @@ struct VideoOptions : public Options
 			level = "4.2";
 		}
 
+		if (strcasecmp(sync_.c_str(), "off") == 0)
+			sync = 0;
+		else if (strcasecmp(sync_.c_str(), "server") == 0)
+			sync = 1;
+		else if (strcasecmp(sync_.c_str(), "client") == 0)
+			sync = 2;
+		else
+			throw std::runtime_error("incorrect sync value " + sync_);
+
 		return true;
 	}
 	virtual void Print() const override
@@ -254,6 +266,7 @@ struct VideoOptions : public Options
 		std::cerr << "    split: " << split << std::endl;
 		std::cerr << "    segment: " << segment << std::endl;
 		std::cerr << "    circular: " << circular << std::endl;
+		std::cerr << "    sync: " << sync << std::endl;
 	}
 
 private:
@@ -262,4 +275,5 @@ struct VideoOptions : public Options
 	std::string av_sync_;
 	std::string audio_bitrate_;
 #endif /* LIBAV_PRESENT */
+	std::string sync_;
 };