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

Claude Heiland-Allen claudiusmaximus at goto10.org
Sun Jun 6 20:33:16 CEST 2010


On 06/06/10 17:35, cyrille henry wrote:
>
> for information : what is the size of the pixel buffer?

either 788x576 or 1044x576, can't remember right now..

>
> thx
> Cyrille
>
> Le 06/06/2010 16:49, Claude Heiland-Allen a écrit :
>> 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
>





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