However, at 96kHz the noise level on analog capture is very high, about -30dBfs. At 88kHz it drops to about -35dBfs. The audio is clear and undistorted, but sounds as if a pink noise generator is summed in as well. This is not a dropped sample, clicking, stuttering problem. No xruns are reported.
In fact, the problem is audible/measurable by just routing the inputs directly to the outputs with via the on-board mixer/router controlled by envy24control -- no host software (e.g., ecasound, arecord) needs to be running.
I wrote to M-Audio Tech support. They advised me to try it under Windows with their drivers. I did this and it worked flawlessly. I noticed that under Windows when I switched from a high sample rate (88.2 or 96) to a low sample rate (48 or 44.1) or the reverse (low to high) there was a loud click on the audio, as if something was being reset. Switching from low to low or high to high did not produce a click.
Under ALSA no click is heard, just the change in the noise level.
I'm running ALSA 0.9.8 on Planet CCRMA Red Hat 9.
[EMAIL PROTECTED] tmp]# uname -a
Linux blumlein 2.4.22-6.ll.rh90 #1 Wed Sep 10 15:43:57 PDT 2003 i686 i686 i386 GNU/Linux
[EMAIL PROTECTED] tmp]# cat /proc/asound/version
Advanced Linux Sound Architecture Driver Version 0.9.8.
Compiled on Oct 28 2003 for kernel 2.4.22-6.ll.rh90 with versioned symbols.
I've captured audio clips at 44.1, 48, 88.2, 96 and placed them at
http://www.ai.sri.com/ajh/audio/delta-1010-noise/
This directory includes the raw output of board, 12-channels of 32-bit samples, as well as 2-channel 16-bit files of the first two channels, and OGG encoded versions of the last files.
The capture and conversion was done by the script test.csh. I also tar'ed the contents of /proc/asound in proc-asound.tar, the wall paper from that shell is in proc-tar-shell, for reference.
Any help or insight would be greatly appreciated.
Thanks...
Aaron Heller <[EMAIL PROTECTED]> Menlo Park, CA
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