[GEM-dev] asynchronous pixel buffer objects for recording etc

[Claude Heiland-Allen]

Hi list,

Is there any way in current Gem to use asynchronous readback of pixel 
buffer objects to speed up recording (or other GPU<->CPU transfer)?

In one of my projects in plain C/OpenGL I used this technique successfully:

1) naive (blocking) glReadPixels direct to CPU ram and piped via
    stdout to ppmtoy4m|y4mscaler|mpeg2enc
-> about 5fps

2) async glReadPixels to pixel buffer object mapped into the CPU
    with one frame latency and piped via stdout to same encoder
-> about 20fps

3) async glReadPixels to PBO to CPU piped via stdout to /dev/null
-> about 25fps

(laptop with 4GB ram, intel core2 dual core cpu, nvidia g105m gpu,
  tested with 32bit gnu/linux/ubuntu/karmic generic-pae kernel)

Thanks for any tips,


Claude
-- 
http://claudiusmaximus.goto10.org