[alsa-devel] [RFC] SGI O2 MACE audio ALSA module

TJ tj.trevelyan at gmail.com
Thu Jul 12 15:24:00 CEST 2007


All playback sounds too fast, some players seem faster then others,
but I maybe wrong on that. The source file's sample rate seems to make
no difference, i've tried 22k,34k,44k,48k.

I have now been given a sin wave generator script, which I've been
meaning to try, but I lack an OCR so I will have to rely on my

ALSA doesn't need to change sample rate, nor will it if the sample is
within the range supported/reported by the driver (as far as i know).

Mace audio supports 8k to 48k. You can look at the set clock speed for
the DAC in /proc/asound/card0/ad1843

You can manually override the clock speed by playing with
ad1843_setup_dac in ad1843.c

You can try lying to ALSA by playing with snd_mace_audio_hw[1] (or
sma_audio_hw[1]) in mace_audio.c

If anyone can see why it plays too fast, please let me know.


On 12/07/07, sknauert at wesleyan.edu <sknauert at wesleyan.edu> wrote:
> Okay, I got the module compiled and it and ALSA installed.
> I noticed the timing bug, I doubt its a frequency issue as the ALSA guides
> to downsample (i.e. if it were doing 48kHz instead of 44.1kHz) didn't
> help.
> You mentioned on some players it would sound okay? I tried everything from
> aplay to xmms and always seemed to play too fast. What CPU are you running
> this on, by the way? Aplay does give underruns if I'm heavily
> multitasking, though sound output seems the same.

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