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Re: audio volume weirdness

der Mouse wrote:
I recently started using i386 3.1 on some new-to-me hardware with
onboard audio

auich0 at pci0 dev 2 function 7: SiS 7012 AC-97 Audio
auich0: interrupting at irq 10
auich0: ac97: C-Media unknown (0x434d4983) codec; no 3D stereo
auich0: ac97: ext id bc2<AC97_23,AMAP,LDAC,SDAC,CDAC,DRA>
audio0 at auich0: full duplex, independent

But I find that using mixerctl to change outputs.master (which is what
I'm used to using, from previous hardware) does not change volume.
I've tried "0,0", "255,255", "0,255", and "255,0" and, for all the
audible difference they make, I might as well have been typing to
another machine entirely.  (It seems to force the low three bits of
each channel's setting to 111, but still, 7 to 255 should be a
substantial difference.)  The only thing that seems to make any
difference at all is setting inputs.dac.mute=on, which silences it, but
a single-bit volume control is..less than useful.

Am I just doing something stupid, or is audio support for this hardware
busted in 3.1 (or perhaps "incomplete" is a better word), or what?

Hi Mouse --

I have the same AC97 codec in a cheap ASRock/VIA motherboard here -- CMI9761 (0x434d4983) codec doesn't support hardware volume controls.

All hope isn't lost though, as I have implemented sw volume controls in the past. Have a look at sys/arch/macppc/dev/snapper.c snapper_volume filter for inspiration. I'm not sure if stream filters were available in 3.1, but you'll be able to figure out a way :)


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