Sending texture from a movie player with ofxSyphon

Hi there,

I’m having strange results while sending a tex from my ofApp to QuartzComposer via ofxSyphon.
The syphon contraption seems to work well in QC since I tried it with different Syphon server from other apps and also with the basic example provided with the ofxSyphon library.
Basically I get some pixels from a movie player, process these and load the processed pixels to an ofTexture that I send with the Syphon server.

It seems like my texture intended for QC is grabbing some area of the screen sometime in my app, sometime outside my app. Some other time the pixels I’m sending appears in QC but behind 2 black triangles covering the picture so finally I only have the top border, the right border and the diagonal from bottom left to top right that show the original pixels. Another time I had a portion of my pixels upside-down and frozen.

When I send my texture to the Syphon Recorder app I have the same result.

I’ve tried many manner to load the data to the texture e.g. with unsigned char* and GL_RGBA type with no success.
I also tried to replicate a piece of code from the basic example inside my app but although it works in the example the same problem appear.

Any idea before I tear off my whole hair ?

Here is part of my code to see how I proceed an a screen capture to see how it look.



int main( ) {

	ofAppGlutWindow window;
	ofSetupOpenGL(&window, 1280, 800, OF_WINDOW);

	ofRunApp(new ofApp());




ofVideoPlayer player;

ofPixels source;
ofPixels processed;

ofTexture processedTex;

ofPixels processVideo( ofPixels pixels);

ofSyphonServer server;

int width = 640;
int height = 380;

float zoomPosX, zoomPosY;
float zoomFactor;
float contrast, brightness, saturation;

bool zoomOn;
bool videoProcessingOn;





server.setName("From my App");

source.allocate(width, height, OF_PIXELS_RGB);
processed.allocate(width, height, OF_PIXELS_RGB);

processedTex.allocate(width, height, GL_RGB);





if (player.isFrameNew()) {

	source = player.getPixels();

	processed = processVideo(source);


processedTex.loadData(processed, GL_RGB);




processedTex.draw(20, 20, width, height);


ofPixels ofApp::processVideo(ofPixels pixels) {

	ofPixels mod = pixels;

	if (zoomOn ) {

		float x = mod.getWidth() * (1 - 1 / zoomFactor + zoomPosX * (1 - 1 / zoomFactor)) / 2;
		float y = mod.getHeight() * (1 - 1 / zoomFactor + zoomPosY * (1 - 1 / zoomFactor)) / 2;
		float w = mod.getWidth() / zoomFactor;
		float h = mod.getHeight() / zoomFactor;

		mod.crop( (int)x, (int)y, (int)w, (int)h) );

		mod.resize(width, height, OF_INTERPOLATE_NEAREST_NEIGHBOR);


	if (videoProcessingOn ) {

		float cfactor = ( 259.0 * ( 255.0 + contrast * 128 ) ) / ( 255 * ( 259 - contrast * 128 ) );

		for (int i = 0; i < mod.getWidth(); i ++) {

			for (int j = 0; j < mod.getHeight(); j++) {

				ofColor c = mod.getColor(i, j);

				float h = c.getHue();
				float s = c.getSaturation() * saturation;
				float b = c.getBrightness();
				b = cfactor * ( b - 128 ) + 128;
				b *= brightness;
				s = ofClamp(s, 0, 255.0);
				b = ofClamp(b, 0, 255.0);
				c.setHsb(h, s, b);

				mod.setColor(i, j, c);



return mod;

Here a screen capture :

Thanks !!!

This is probably (hopefully) not your actual code - you’re passing ofPixels not ofTexture. Perhaps you can share the actual code you’re using.

Hi Bangnoise,
Yes sorry there was some mistakes, I did an edit.
This not the original code which is very long but it reproduce where I get the pixels and what I am doing with.
I can add that the “processedTex” draw without any problems.

I’m having the same issue, did you ever find a solution?

Hi, I finally did not use Quartz Composer so I didn’t try again but maybe I would give a try with a GLFW context instead of GLUT now.

Can you provide a minimal example which reproduces your issue?

I ended up fixing my issue, but I can’t remember what was causing it exactly!

It was something like a fill command or setColor before the syphon out. It was causing what was being displayed on the OF window to be normal but the Syphon out would have some square over it.

Do you remember how you fixed it?

My ofxSyphon was working fine for a while but now the server only shows a black screen with a diagonal line across it. I’ve noticed that this happens whenever I draw a shape with ofNoFill(). I haven’t isolated the problem because when I create a new, simple oF project and create a box with ofNoFill(), ofxSyphon works fine. However, the project I am having this issue with is fairly complex so I haven’t isolated the issue beyond ofNoFill(), yet.

I got as far as you. In my case, removing the ofNoFill() fixed it for me. Maybe you could then (as needed, before syphon out) to a ofSetFill(255,255,255) and it’d work?

You can try things like ofClear( 255, 255, 255 ) and/or ofSetColor(255) just before drawing the texture.

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Thanks for your replies. I will try them tonight.

I’ve since also noticed that placing the publish call before drawing my ofxGui and after it also affects the output. If I place the publish call after drawing my ofxGui, it works correctly occasionally, and placing the call before ofxGui no longer ever works, even though it used to.

I say ‘occasionally’ because even then it stops working and resumes working arbitrarily.

Calling ofFill() at the end of your draw loop - but before publishing the screen with ofxSyhon - seems to work.

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