21 Feb
2005
21 Feb
'05
8:45 p.m.
Am Montag 21 Februar 2005 18:09 schrieb Rui Nuno Capela:
Spencer Russell wrote:
yes , us428 has 4 ins & 2 outs. to make it work with latest jack alsa driver,
you have to hardcode 2 in channels in jack/drivers/alsa/alsa_driver.c like this:
The US428 has 4 capture channels and 2 playback
channels. Capture
channels 3 and 4 are switchable between analog and digital. The
button to switch doesn't seem to do anything, though.
-spencer
On Mon, Feb 21, 2005 at 09:05:32AM +0000, Rui Nuno Capela wrote:
>
> BTW, shouldn't the US-428 have 8 playback channels, the US-224 have 4,
> and finally 2 for US-122?
>
I took a quick look into Karsten's original jackd usx2y_driver code and...
I'm affraid that the number of channels were being hardcoded as 2 for
capture and 2 for playback.
OTOH already in the current jack CVS trunk, the number of channels are
either given on the jackd command line (-i,-o) or taken from the maximum
allowed by the ALSA driver (via snd_pcm_hw_params_get_channels_max()).
Maybe its around here where the issue is? Karsten?
I could also check that the jackd usx2y specific code has support for no
more than 4 capture and 2 playback channels.
>>>>>>
---
alsa_driver.c.~1.65.~ 2005-02-22 01:15:07.000000000 +0100
+++ alsa_driver.c 2005-02-22 01:16:32.000000000 +0100
@@ -450,7 +450,7 @@
}
if ((err = snd_pcm_hw_params_set_channels (handle, hw_params,
- *nchns)) < 0) {
+ 2 /* *nchns*/)) < 0) {
jack_error ("ALSA: cannot set channel count to %u for %s",
*nchns, stream_name);
return -1;
<<<<<<<
confusing, no? (even annoying, if you also use other cards with more than 2 in
channels...)
its because the alsa layer doesn't correctly know about us428's channels 3 + 4.
in raw-usb mode some standard parts of alsa pcm are bypassed, and so currently you can
only use
us428's 4 in channels with the above hack.
It works only, if you call jackd like this:
$jackd -dalsa -dhw:n,2
with n being the us428 alsa card nr.
You have to use latest snd-usb-usx2y, which is already in kernel >= 2.6.11-rc3 .
and it only works with jack. plain alsa only knows us428's first 2 channels.
beware of calling jackd with -dhw:n,1! it can crash your machine as i just experienced.
digital in doesn't yet work.
will make the above hack obsolete hopefully before spring;-)
best regards,
Karsten