[LAU] CM6206 S/PDIF JACK input

Dan MacDonald allcoms at gmail.com
Tue Nov 13 00:24:27 UTC 2012


Hi Len!

Thanks for your reply but it seems like half an answer to me as you didn't
tell me what to do with the output of arecord -L?

I found a seemingly relevant thread on the LM forums where someone managed
to get their SPDIF working under JACK by writing a custom ALSA config file
but there wasn't quite enough hand-holding to get things working for me
unfortunately. I have posted all the previously mentioned info on my device
as well as the output of arecord -L to

http://linuxmusicians.com/viewtopic.php?f=27&t=8898

Thanks for your help Len and anyone else who can offer me any guidance here!


On Mon, Nov 12, 2012 at 9:00 PM, Len Ovens <len at ovenwerks.net> wrote:

>
> On Mon, November 12, 2012 12:11 pm, Dan MacDonald wrote:
> > Hello LA land!
> >
> > I got a Startech USB audio device based on the C-Media CM6206 purely in
> > the
> > hope of being able to use its S/PDIF input under JACK. It runs JACK just
> > fine, I just don't know how I might access the SPDIF input (or even the
> > line-in, just out of interest) from under JACK?
> >
> > When I run alsamixer and switch to viewing the capture ports of the
> cm6206
> > there are 4 capture channels - PCM, Line, Mic and S/PDIF In but under
> JACK
> > I only get 2 capture ports which are the L and R analogue mic input
> > channels. I can also see the light emitting from the S/PDIF out port so I
> > am confident the S/PDIF should work and hopefully under JACK.
>
> Ok, first thing to try is to make sure you can see the s/pdif inout with
> alsa. audacity or arecord should be able to record audio (audacity
> provides metering which may make things easier). alsamixer does not show
> capture ports it shows volume controls or switches. Often you would have 3
> or 4 inputs that are switched/mixed to give one stereo input. So making
> sure your s/pdif channel is on/unmuted/turned up is the first step. You
> may wish to mute Line and Mic while playing with it. You probably (from
> what you have said) have:
>
> Mic-------------\
>                  \
> Line----------| Mixer |------PCM------>ALSA-->Jack
>                  /
> S/PDIF----------/
>
> Each line here would be a stereo path (two Channels).
>
> In other words I think you will find there are only two input channels to
> ALSA.
>
>
> > card 2: Device [USB Sound Device], device 0: USB Audio [USB Audio]
> >   Subdevices: 1/1
> >   Subdevice #0: subdevice #0
>
> Assuming this is the device notice this doesn't shows number of channels.
>
> >  11: [ 2- 0]: digital audio playback
> >  12: [ 2- 0]: digital audio capture
> >  13: [ 2]   : control
> >  33:        : timer
>
> Or this... but they don't on my 4channel+spdif card either.
>
> Try arecord -L
> (Capital L)
>
> It still doesn't show number of outputs directly but rather choices, There
> it lists stereo as:
> front:CARD=M66,DEV=0
>     M Audio Delta 66, ICE1712 multi
>     Front speakers
> and spdif as:
> iec958:CARD=M66,DEV=0
>     M Audio Delta 66, ICE1712 multi
>     IEC958 (S/PDIF) Digital Audio Output
> To use my 4 analog inputs I would use:
> surround40:CARD=M66,DEV=0
>     M Audio Delta 66, ICE1712 multi
>     4.0 Surround output to Front and Rear speakers
> This one here _might_ be my analog inputs plus spdif:
> surround51:CARD=M66,DEV=0
>     M Audio Delta 66, ICE1712 multi
>     5.1 Surround output to Front, Center, Rear and Subwoofer speakers
> I say might be because jack actually show 12 inputs:
>    1-4 are analog
>    5-8 are not used but defined for the ice1712
>    9-10 spdif
>    11-12 monitor mixer output
> So the last two inputs in 5.1 might actually be the dead inputs 5-6
>
>
> --
> Len Ovens
> www.OvenWerks.net
>
>
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