M-Audio Audiophile USB

M-Audio Audiophile USB

[Pierre-Antoine Champin]

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Hi alsa people,

I bought an M-Audio Audiophile USB external sound interface, but I have
some problems to make it work properly: when recording audio, the signal
I get is completely saturated. Googling around didn't help much, so my
question is:

- to alsa-user: is anyone owning such a card and having it work? If so,
what is your configuration?

- to alsa-devel: what is the known level of support for this card? if it
is known to work 100%, what may I be doing wrong? if not, how may I help
fix it (see below)?

I may have found the solution, though:
when I record a raw file with
  arecord -D hw:3 -t raw -c 2 -r 48000 -f S24_3BE >foo.raw
and play it with the same option, I get the saturated sound, as I wrote.
However, if I change the order of each 3-uple of bytes like that
    a,b,c -> c,a,b
and play the resulting file with the options above, it sounds good.

So I guess that the card has uses format S24_3BE for output, but *not*
for input; it uses instead some hybrid format, for which the conversion
to low endian would be:
    a,b,c -> b,a,c


Unfortunately, I'm not familiar enough with driver development to be
able to fix it right away, so I prefer to submit it on the list first.
I'm able to code, though, so with a few pointers, I may be able to do
it. I'm just not sure which is the most time consuming for a
knowledgeable developer: doing it or helping me into doing it ;)


 thanks in advance

  pA


PS: I'm using a Debian (testing) distriburion, with kernel 2.6.10
(I also tried with Agnula Demudi, based on 2.6.12)

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Re: M-Audio Audiophile USB

[Clemens Ladisch]

Pierre-Antoine Champin wrote:
> I bought an M-Audio Audiophile USB external sound interface, but I have
> some problems to make it work properly: when recording audio, the signal
> I get is completely saturated.
> [...]
> So I guess that the card has uses format S24_3BE for output, but *not*
> for input; it uses instead some hybrid format, for which the conversion
> to low endian would be:
>     a,b,c -> b,a,c

The driver currently assumes that both playback and capture use
big-endian samples.  I haven't heard any complaints since this was
implemented 21 months ago.

Does it work if you use plughw:3 and .wav files?


Regards,
Clemens



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