Re: ALSA Sound doesn't work right
On Wed, Jul 31, 2002 at 02:21:56PM +0200, Roland Wegmann wrote:
>
> After that I did an alsa restart and started alsaplayer or xmms to play an
> mp3 file. In both cases I could hear sound. Using alsaplayer in a real bad
> quality and only when I set volume to 1%. Above 1% alsaplayer plays only
> white noise. When I use xmms the sound has a high quality, but I can't adjust
> the volume or the balance, whereas in alsaplayer both work fine.
>
> Could someone help me by the configuration of my alsa sound system, please?
>
This is because ALSA does not (yet) support the ADC chipset -- referred
to as snapper by apple -- found in newer systems. The change only
affects the mixer portion of the driver, which means that sound output
is correct using the tumbler driver, but writing anything at all to the
mixers causes big problems due to a very different register layout.
The latest benh kernel has my patches to support snapper, and fixes this
problem. The volume response is still not perfect, but I have a volume
table now which is much better. I intend to check this in soon, along
with support for DRCE and equalisation.
You can determine your chipset by doing the following:
[toby@phalaris] 510 $ xxd `find . -name sound | grep -v aliases`/compatible
0000000: 736e 6170 7065 7200 snapper.
If you have OSX installed, you can also check out the loaded kernel
extensions (man -k kernel to find the command you need). You need to do
this as root (you can change the root passwd to something you know with
'sudo passwd root' as any administrator).
If it lists AppleTexasAudio2, then it's likely you have snapper. Sadly
the AppleTexasAudio2 code doesn't seem to have made it into the Darwin
CVS repository.
I don't intend (at the moment) to add support to ALSA, even though IMHO
it's a much better thought out set of sound drivers, mostly as a result
of a lack of time.
All any prospective ALSA modifier needs to know is that snapper replaces
the tas3001c with the tas3004. PDFs are available from the Texas
Instruments website.
This is where I found out what the change was (in Japanese, but with
pictures, and readable part numbers):
http://www.medicalmac.com/mac95.html
Toby.
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