Subject: Re: [ecasound] Problem with ALSA full duplex and SB Live
From: Kai Vehmanen (kaiv@wakkanet.fi)
Date: Wed Jun 20 2001 - 02:48:02 EEST
On Tue, 19 Jun 2001, Josh Green wrote:
[ testing with the vocoder plugin ]
> I did some more testing with regards to using full duplex with ALSA
> 0.9.0beta4 and an SB Live. It appears that the popping and clicking
> sounds start getting generated after under/over runs, although the
> clicking continues on, even after the under/overruns have stopped. It
> almost seems like the input/output buffers get out of sync or something.
> I'm running a test with the Creative EMU10K1 (OSS based) opensource
> driver with no problems so far (running for quite sometime). I was
I've ran my vocoder setup for over an hour now without problems. Linux
2.4.5smp, ALSA CVS (~beta4), ens1371/sb128 and ecasound 2.0.1. I've tried
both native ALSA access (xruns handled ok), and the OSS-emulation. So it
seems the problem is specific to emu10k1's ALSA drivers (and specifically
the full-duplex operation).
> wondering if you think this could be a problem with ecasound or if I
> should consider it an ALSA issue?
Now this is a very difficult question, because the new ALSA API hasn't
seen much testing (or more accurately, lots of testing but only with a
small set of apps like OSS emulation, aplay, ardour and ecasound). Anyway,
finding the problem should interest both ALSA and application
developers. If it's turns out that ecasound is misusing the new API in
some respect, this case should be clearly documented. So in any case, the
problem needs to be traced and debugged...
Few things to test with ecasound:
- different arguments to -b:xxx (in ALSA terms, xxx is the
period/fragment size in sample frames; default is 1024,
values worth trying out range from 128 to 4096)
- -z:nointbuf (only 3 fragments in use) and -z:intbuf
(use as many fragments as possible)
- differences between the plugin and hw interfaces
(-i:alsahw,0,0 <-> -i:alsaplugin,0,0)
... these all affect the way ecasound uses the ALSA API.
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