23 Dec
2006
23 Dec
'06
11:03 a.m.
Mario Lang wrote:
Hi.
I just tried to get sound working on a LinkSys NSLU2 (ARM) running
Debian Etch using a USB sound card.
What I discovered I find pretty strange, and would like to know some
more details. Apparently, all ALSA native clients don't
manage to play sound click-free, they actually have underruns all the
time. However, if I use OSS (via the snd-pcm-oss module) and set
libao to use the oss driver, I get perfect playback with about
20% CPU use at maxiumum by the user-space app playing/decoding files.
This is a bit strange, isn't it. OSS-emulation actually uses the same
kernel code to access the actual hardware. I am just very vaguely
familiar with the whole ALSA architecture, but it feels as if
the problem here actually lies inside the user-space alsa libraries?
Did anyone ever see such an effect, and investigate more closely
what is the reason for the difference?
Which applications have this problem?
What quite often happens is an application's ALSA interface code is
written wrongly. For example, if the application uses OSS is uses a nice
big sound buffer, so no clicks, but if the application uses ALSA, it
requests minute buffer sizes that results in lots of clicks.
So, please explain which applications have the problem.
James