[Alsa-user] 1/2 sec delay with oss emulation in direct mode

[Atte André Jensen]

I'm having quite a bit of trouble getting csound to use my edirol usb 
soundcard. Cor those not familiar with csound, it can be called with an 
option -o for which device to use. Calling it with /dev/dsp worked fine 
(but that was the onboard card). However /dev/dsp0 (same card, /dev/dsp 
is a symlink to this) and /dev/dsp1 (the edirol) produced only noises.

After many things tried I found: 
http://alsa-project.org/~iwai/OSS-Emulation.html
and after reading the section on quake I got the idea to try:

echo "csound 0 0 direct" > /proc/asound/card1/pcm0p/oss

Which produces noisefree audio on the edirol (available still on 
/dev/dsp1). But.... The audio is delayed about 1/2 second. Since I use 
csound as a realtime synthesizer controlled from midi keyboards I need 
as low latency as possible. Any ideas how to achieve this???

I have my eyes on the fragments fragment_size parts of the call, but I 
don't know what values to use...

NB: Doing the same trick on the onboard card made /dev/dsp0 work from 
csound as well, but transposed a few octaves down and delayed about 2 
seconds. Thought that behaviour might be useful to know about also...

NB2: My system is a PIV 2.4G laptop with an onboard i180 soundcard and 
an edirol UA-1A UBS soundbcard, running kernel 2.6.4 and debian/unstable.

--
peace, love & harmony
Atte
http://www.atte.dk

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