ICH4 Sound Support?

Orion Hodson orion at freebsd.org
Sat Apr 5 08:26:14 PST 2003

Drew Tomlinson writes:
| I've been fighting with getting sound working on FBSD 5.0-RELEASE-p7.  Can
| someone tell me if the pcm driver is supposed to work with ICH4 integrated
| sound on an Intel motherboard?  I read in the 5.0 release notes that there
| is rudimentary support.  However when I attempt to play an mp3 file, the
| quality is very bad.  Lots of static and hissing.  If I play an audio CD, it
| plays just fine.

Drew, based on what you say above, there's a reasonable chance you
have an AC97 codec attached to your ich4 sound controller that does
not support variable rate audio.  In this case the kernel does sample
rate conversion from mp3 rate (typ. 44.1kHz) to the fixed rate
(48kHz).  The code on the RELENG_5_0 branch does not cope well with
this conversion.  However, this is fixed on the HEAD branch (as of early

In this particular case, you should be able to just copy the file
between branches and rebuild and reinstall the kernel or kernel module
if using it.  The appropriate fetch and inplace copy is:

	% fetch -o feeder_rate.c 'http://www.freebsd.org/cgi/cvsweb.cgi/~checkout~/src/sys/dev/sound/pcm/feeder_rate.c?rev=1.9&content-type=text/plain'
	% cp feeder_rate.c ${SRC}/sys/dev/sound/pcm/

If this doesn't work or you can't make it compile, let me know.
Kind Regards
- Orion

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