Recording from jit.gl.render

Hi,

i have a patch in which i render different shapes using jit.gl.render. When i make a window with the render name, it will directly render to the window. Now i want to make a recording of it, but this is not possible since there is no jitter-patchcord that i can connect to a jit.qt.record object. I have reprogrammed the patch so the jit.window is gone, and instead the jit.gl.render object renders to a matrix, with 800x600 dimension. This i can record....but it is extremely slow when recording, and when i want to check the recorded movie it seems to get stuck when playing. Although the complete movie is recorded, it can not be played and i don't exactly know why. Should i use a certain codec? (jit.qt.record uses raw codec by default) or should i just use an external desktop recorder and not do this within MAX/Jitter?

Thanks for any help.