On Friday, January 07, 2011 04:18:57 pm Gabriel M. Beddingfield wrote: > Before I FUD someone else's application... a perfect > example is StretchPlayer (using RubberBand). I can't > get it to be RT-safe at <256... and it's marginal at > 256. FYI, I did some testing with RubberBand and found that it has a fixed minimum processing window/time of 512 frames. This makes it dangerous to use with <512 frames/period because it does too much work in one period. For example, at 64 frames/period I measured these processing times for subsequent process() cycles: Process time = 1533 usecs Process time = 1851 usecs Process time = 1787 usecs Process time = 26 usecs Process time = 18 usecs Process time = 20 usecs Process time = 22 usecs Process time = 19 usecs Process time = 18 usecs Process time = 21 usecs Process time = 22 usecs Process time = 20 usecs Process time = 17 usecs Process time = 18 usecs Process time = 21 usecs Process time = 18 usecs Process time = 21 usecs Process time = 26 usecs Process time = 22 usecs Process time = 27 usecs Process time = 20 usecs Process time = 30 usecs Process time = 27 usecs Process time = 66 usecs Process time = 1893 usecs Process time = 18 usecs Process time = 29 usecs Process time = 24 usecs Process time = 20 usecs Process time = 18 usecs Process time = 22 usecs Process time = 18 usecs Process time = 1518 usecs Process time = 20 usecs Process time = 21 usecs Process time = 23 usecs Process time = 21 usecs Process time = 17 usecs Process time = 22 usecs Process time = 21 usecs Process time = 1654 usecs I.e. it does all its calculations every 8 periods (512/64)... instead of doing a little bit in each period. This behavior makes it dangerous to use RubberBand at less than 512 frames/period because it eats up your processor headroom. However, if you have a really fast processor you can usually get away with it. It looks like it's possible to make the window smaller by hacking RubberBand... but I can't figure out how to do it through the public API. -gabriel _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
