Subject: Re: [ecasound] Problem with ALSA full duplex and SB Live
From: Josh Green (firstname.lastname@example.org)
Date: Wed Jun 20 2001 - 13:55:12 EEST
I downloaded the latest version of ALSA via CVS to see if it would fix
the problem I'm having with non-overrun/underrun related pops and clicks
in PCM output in full duplex mode with an SB Live card that occur after
a period of time >15 minutes (re-stated for alsa-devel).
I tried various ecasound settings, the problem is still there.
Using OSS emulation (/dev/dsp) versus ALSA hw (-i:alsa,"hw:0,0"). Same
clicking/popping with either driver interface, suggesting that its an
internal ALSA driver problem (using OSS mode with the emu10k1 Creative
driver does not seem to have this problem).
Different -b:xxx arguments: The buffer length affects the length of time
it takes for the problem to occur and also the interval the clicking
occurs once it starts (smaller buffer -> problem occurs within a shorter
period of time and clicks occur much faster). 256 sample buffers is the
lowest somewhat "stable" setting (no clicks for much longer period of
time). 1024 is even better.
I tried z:nointbuf/intbuf, though not thoroughly tested. Not sure if
this helped or not.
From what I'm seeing I would guess that it is a sync problem between the
record and playback buffers, almost like what you would see when trying
to do full duplex with 2 different sound cards. The pops and clicks only
occur when there is sufficient output on the PCM interface (sudden
changes in PCM amplitude caused by wrong fragment being played?)
At this point, my personal guess is that its not an ecasound related
problem. I'll do some more testing. Perhaps someone on the alsa-devel
list might know whats going on. Lates..
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This archive was generated by hypermail 2b28 : Wed Jun 20 2001 - 13:54:47 EEST