Re: Audio, Soundbylayout: how to use it at 24 bits/96 KHz

[Wolfgang Pfeiffer <roto@gmx.net>]

On Sun, Aug 16, 2009 at 03:53:20PM +0200, Wolfgang Pfeiffer wrote:
> Hi All
> 
> PowerBook5,8 here.
> 
> I want to play a sound file that is coded to 24 bits/96000 Hz at
> exactly these sample rates. 
> 
> $ file 24-96-sound.wav 
> 24-96-sound.wav: RIFF (little-endian) data, WAVE audio, Microsoft PCM, 24 bit, stereo 96000 Hz
> 
> Apple says the soundcard I have is able to do 16 or 24 bits, and
> sample rates of up to 96KHz:
> 
> "The audio circuitry and audio device drivers handle audio data in
> multiple formats. Both digital and analog audio circuitry handle audio
> input and output data at sample rates of 32.0 kHz, 44.1 kHz, 48.0 kHz,
> 64.0 kHz, 88.2 kHz, and 96.0 kHz at sample depths of 16 bits and 24
> bits."

1:

Meantime I doubt this card can do 24 bits: after lots of testing it
looks it can do 16 and 32 bits only.

2:

I found and installed/edited an old ~/.aoundrc file. You find it
attached to this email. It works in that it uses a fixed sample rate
of 96000 Hz for anything you feed to your different sound players. I
hate this solution, as nowadays alsa simply should look at the file
that's fed to it, and then - per default - play it exactly as it was
coded, limited only by the capabilities of the sound card: e.g. a file
with 96000 Hz should be played at exactly that rate, and one with
44100 Hz with 44100 Hz.

But it's a - so far - working compromise. If in doubt don't use the
attached ~/.asoundrc: I cannot guarantee it won't break things on your
system.

3:

Thanks to Michel Dänzer who - if my memory serves me well - published
an .asoundrc many years ago that helped me set up most parts of the one
attached to this email. Again, don't use it: things might have changed
greatly meantime ...

HTH

Best Regards
Wolfgang
-- 
http://heelsbroke.wordpress.com