Re: [linux-audio-user] Latency with ALSA

I am writing audio applications that are real-time. I had been using Port Audio which is really very good, even without root priviledges, it does a very good job. I want to support other sound drivers, in case someone doesn't have Port Audio or can't get it to work. I have just built my ALSA driver, it works ok, but I am getting terrible latency problems and buffer underruns. The thing is it is a real-time application, it must get audio to the card as soon as possible. Why is it that OSS with Port Audio works so well, and my ALSA setup is suffering? Even if I set the frame rate higher (the number of frames to the card) I still get buffer underruns. I am talking maybe 70 milliseconds now. This is sad, because I know with DirectX I can get about 35 ms timing with it on this machine.With ASIO I have done better than that. Even running as root and scheduling the app to real-time priority (50) I get buffer underruns. So, something must not be right with my setup. I have tried setting the frames written to all sorts of latencies, and it does reduce the drop outs, but I am still getting them. I tried buffering the sound and dropping it in blocks, but it wasn't working correctly. This is a bit disappointing so far. Is there something I need to do to ALSA to get near real-time performance from it? I have heard people mention patching their kernel for low latency. I have Jack but I have not started working with it yet. Should I dump ALSA and just go for Jack? Is there something I need to do to my kernel to get better performance? I would get Planet CCRMA if it supported my OS, but it doesn't, so I have to tweak my box manually. Thanks -- Nick <nicktsocanos(a)charter.net>