Hi.
I have not read/understand what you are trying to explain because my
english level is not native language (sorry). But i can tell you
something:
For audio works, i recommend you using JACK (with a realtime kernel).
Gracias.
Chau!
On Sat, 2011-01-22 at 11:07 +0000, Jim Lesurf wrote:
> Hi,
>
> This is my first posting to the email list. I have looked at the archives,
> but apologies if the following is too far OT or an old chestnut.
>
> I'm experimenting with two different USB sound (playing) devices that
> should be capable of asynchronous transfers up to and including 96k/24bit.
> The following is when testing a Halide Bridge. Using two systems, but the
> one relevant here is a Shuttle running Ubuntu.
>
> I've successfully arranged for the device(s) I'm trying out to be the
> 'default' alsa device for playing by including
>
> pcm.!default {
> type plug
> slave {
> pcm "hw:2"
> channels 2
> format S24_3LE
> }
> }
>
> in my 'asoundrc' file. (NB there are two other 'soundcards' present and the
> one I'm testing expect S24_3LE and is hw:2.)
>
> The Halide Bridge converts USB into (coax) SPDIF.
>
> If I play a 96k/24 LPCM wave file with the aplay command I can record its
> SPDIF output with an audio recorder and compare it sample-by-sample with
> the file I played. Using aplay, the result for the brief tests so far show
> bit-for-bit correct output values. So that looks like the Bridge and
> Shuttle hardware are working OK.
>
> However if I use Audacious to play a file, the result comes out as 16 bit
> per sample. i.e. the least significant byte is being ignored/zerod. I have
> selected the '24 bit' output option, and specified not to use its volume
> control. I have also selected the 'advanced' option to 'avoid processing'
> and have selected the default ALSA output.
>
> Have I missed something with Audacious? Or is this a known problem? I've
> found on the web mentions of making sure you select the 24bit output and
> the 'avoid processing'. And apart from the missing bottom 8 bits the values
> don't immediately look 'altered' in other ways. Not looked yet in detail
> though as the loss of the lowest bytes is the obvious symptom!
>
> Can give more details if asked, but at present not sure what to add and
> wish to avoid taking up too much space if this is OT or a chestnut.
>
> Thanks in advance for any help,
>
> Jim
>
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