Subject: Re: [linux-audio-user] sounblaster live platinum and full-duplex recording (noisy)
From: Lee Revell (rlrevell_AT_joe-job.com)
Date: Sat Aug 14 2004 - 07:09:36 EEST
On Fri, 2004-08-13 at 23:30, Erik Steffl wrote:
> recording seems to be working OK but:
>
> in audacity when I record the track it sounds OK
>
> however if I generate click track and record then (the click track is
> playing while I am recording) the recording is really bad (noisy, low
> quality).
>
> I vaguely remember something about full-duplex on sounblaster not
> being very good, i.e. there's something wrong when using it but don't
> remember what (bitrate being forced to be very low or something along
> those lines).
>
> However I can't find any information on that subject now (I tried
> google and creative site), does anybody know details and/or have some
> pointers to relevant docs?
>
> system: debian unstable, 2.6.5 kenrel (with alsa), sounblaster live
> platinum (with live drive).
>
The hw:x,0 capture device on the sb live is not very good. For good
results you have to use the hw:x,0 playback device and the hw:x,2
capture device. You have to use 48khz.
To record at the lowest latencies you have to record more than 2
channels. This is because the capture buffer size is fixed in bytes;
doubling the number of channels halves the amount of time between
interrupts with a fixed buffer size.
This did not work at all until very recently, I believe you need the
ALSA 1.0.6-rc1 release candidate.
Search the recent alsa-devel archives for 'emu10k1 low latency capture'
and 'emu10k1 multichannel' for more info.
Lee
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