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
--
Electronics http://www.st-and.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html
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