ofxSquashBuddies

Image courtesy of the Boston Public Library, Leslie Jones Collection.

ofxSquashBuddies is a very low-latency system for transmitting data across a network.

When transmitting a 4MB image over a dedicated GigE connection, we had < 1 frame latency 30fps, at less than 5% CPU on both sender and receiver. 1080p YUY, 720p RGBA or a Kinect V2 RGB+D+Skeleton frame are all approximately 4MB.

Why is it so fast?

We've made quite a few speed optimisations:

Send whilst we are compressing (i.e. don't wait for 1 to finish before starting the next one on another thread. This means same amount of computation is required but overall latency is significantly reduced).
Decompress whilst we are receiving
We use the Density compression algorithm (approx 2x faster than Snappy at around the same compression ratio).
We use ASIO socket library (as used by GigE Vision libraries).
We use blocking networking on dedicated threads with condition variable syncing (this gives more performance than async routines).

All of these systems are open source and cross platform.

Requirements

ofxAsio - https://github.com/elliotwoods/ofxAsio
ofxSquash - https://github.com/elliotwoods/ofxSquash
ofxAddonLib - https://github.com/elliotwoods/ofxAddonLib (optional for Visual Studio, not required on other platforms)

Usage

Sending

void ofApp::setup(){
	this->sender.init("127.0.0.1", 4444);
}

void ofApp::update(){
	this->video.update();
	if (this->video.isFrameNew()) {
		this->sender.send(this->video.getPixels());
	}
}

Receiver

void ofApp::setup(){
	this->receiver.init(4444);
}

void ofApp::update(){
	if (this->receiver.isFrameNew()) {
		this->receiver.receive(this->image.getPixels());
	}
}

Compatability

Tested with openFrameworks 0.9.1 on OSX and Windows. This addon should work on all platforms where ofxSquash and ofxAsio are supported.

Credits

ofxSquashBuddies is developed by Elliot Woods and Satoru Higa.

License