On Sat, Dec 20, 2003 at 04:14:52PM -0800, T. Joseph Carter wrote:
> Windows tries hard to hide this from you, but you basically have two sound
> cards. One of them is analog, the other is digital. All of your analog
> connections on the card go through your AC97 chip. Your analog speakers
> also run through the AC97. The AC97 has an aux output that goes to the
> EMU10k1 (or 10k2 for Audigy) chip. This card controls digital speakers
> and has the effects processor and whatnot. It handles wavetable (only
> matters with ALSA, OSS drivers don't support this function) if you're
> using the card as a MIDI synth, PCM sound (playing wav or mp3 files), etc.
> It also controls the {Live,Audigy}Drive, if you have one of those.
>
> The reason why this matters is that, the emu10k1 also routes back into the
> AC97 chip via its PCM input. This means it's possible to create feedback
> loops and the like when fiddling with the various mixer settings, etc.
> Also, what you hear out of analog speakers may not match what you hear out
> of digital ones. Doing it this way means it's a little less flexible than
> it could/should be, but it allowed Creative to use an off-the-shelf AC97
> chip and save some green.
>
> To configure this beast, you want alsamixer. And you want to hit the
> emu10k1 ALSA wiki page, though you'll have to google for that since I do
> not remember where it is now. alsamixer has LOTS of settings, and most of
> them you will be able to change there, but should not. Their values make
> no sense anyway, they're actually switches and things you'd set with
> another program. The wiki page will have details.
> You're missing a lot of somethings, mostly in that the driver is far more
> complex than you bargained for because, although ALSA tries to simplify
> the setup a little bit, its mixer ends up complicating things. The OSS
> drivers can do more (eg, use the effects processor), but you have to
> control all of the emu10k1 functions with seperate programs that use
> neither OSS nor ALSA control mechanisms. In OSS at least, the OSS mixer
> controls are tied to the card's AC97 controls, so unless you have digital
> speakers or so you're probably good to go.
Well, I can control PCM routing with alsamixer for my Audigy ... sort
of (the control is there, but it doesn't seem to work ... I don't have
digital speakers anyway). I just switched the card to analog output with
alsamixer.
Anyway, most sound apps are being built for ALSA. Also, JACK is built
for ALSA.
--
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