The guy's definitely brilliant. But it doesn't seem like he's going to share his source code any time soon. is he?liz wrote:Phil Atkin's work is worth checking out: http://raspberrypisynthesizer.blogspot.co.uk/
Thank you for the reply, I have read that article before, but I haven't tried to compile a real time kernel. Can anyone confirm that raspbian doesn't have a real time kernel by default? Also, has anyone tried to compile a real time kernel and have noticed better performance with Jack?Sleep Mode zZ wrote:I have had similar issues with my desktop computer. The crackling probably is just buffer underruns. I suffered sometimes from it when the CPU usage was not even close to 100%.
I can only speculate about possible reasons as I have not played with jack audio on the Pi. Maybe jack or the synths can't make use of all 4 cores and because of that you have buffer underruns with lower CPU usage than you expect? Your Core 2 Duo machine, although many years old, probably has several times better single thread performance. Maybe the programs are better optimized for x86 architecture?
Audio specialized Linux distributions use a low latency or real time kernel. Using those, it is possible to prioritize audio related threads over everything else running on the machine - and as such minimize the risk of buffer underruns.
Avoiding buffer underruns while having low latency seems like black magic to me, so it is better to just point you to http://wiki.linuxaudio.org/wiki/raspberrypi, in case you have not already read it.
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A-System:~$ uname -r 3.19.0-15-lowlatency