[linux-audio-user] ecasound question with RME hammerfall lite.

[Stephen Cameron]

Kai, thanks for the reply.
I have a few more questions.

--- Kai Vehmanen <kvehmanen at eca.cx> wrote:

> Hello,
> 
> On Wed, 6 Dec 2006, Stephen Cameron wrote:
[...]
> 
> > ecasound -c -r -b:128 -a:1,2 -i jack -o drums.wav -a:3,4 -i jack -o guitar.wav
> 
> This will work, but some notes:
> 
>   - you don't need to give "-r" (automatic if sufficient privileges) or
>     "-b:128" (learned from jackd)
>   - the routing is somewhat wrong, as chains 1-4 (defined with -a) are
>     by default all stereo, so you for instance end up routing audio from
>     "-i jack" (two channels) to two stereo chains (2x2 channels) which
>     are again mixed back to "drums.wav" (again two channel)

This confuses me.  In qjackctl's connections screen, I see 18 capture
channels on the RME.  My impression is that these are mono, not stereo.

I need to capture 4 of those channels, two for drums, two for guitar.
When I start ecasound like this:

> ecasound -c -r -b:128 -a:1,2 -i jack -o drums.wav -a:3,4 -i jack -o guitar.wav

Then ecasound has 4 inputs that I can connect the 4 capture channels to.

Maybe it is the "-i jack" listed twice that makes 4 input channels on 
ecasound?   Previously I had tried something like:

> ecasound -c -r -a:1,2,3,4 -i jack -a:1,2 -o guitar.wav -a:3,4 drums.wav

and that didn't work, I got two input channels on ecasound, and well,
that wasn't what I needed, so I was kind of thrashing around a bit
trying to discover just what all the options really do.  (I did read
the man page, it's how I've gotten as far as I have, but it's rather 
succinct. :-)

> 
> What you probably wanted is (mono track for drums and guitar)

Actually, I need stereo for drums and stereo for guitar, and
generally I'll be wanting to transfer up to 4 stereo tracks
at once, or any combo of stereo and mono totalling up to 8 
captured channels (I have just 1 ADAT connection from the
AW4416, so, 8 mono channels.)

> sh> ecasound -c -f:32,1,44100 -a:drums -i jack -o drums.wav -a:guitar -i jack -o guitar.wav
> 

I'll give that a try later tonight.  I'm confused as above you
say "-i jack" gives a stereo chain, but you also say above
"(mono track for drums and guitar)"  Perhaps you meant "stereo"
rather than "mono"?   Or am I misunderstanding something still?

> More info about ecasound's JACK support and the routing logic can
> be found at:
> 
> http://eca.cx/ecasound/Documentation/users_guide/html_uguide/users_guide.html#htoc50
> http://eca.cx/ecasound/Documentation/examples.html
> http://eca.cx/ecasound/Documentation/ecasound_manpage.html (search for JACK)
> 

Yeah, I had found those.  An example of recording multiple channels
from JACK would would have helped me a lot.  (Well, maybe it's asking
too much to hope someone would anticipate exactly what I want to do
and provide an example. ;-)

> If you want to play with JACK and ecasound, try also ecasignalview:
> 
> ecasignalview jack_alsa null
> ecasignalview jack null
> ecasignalview jack_alsa foo.wav
> ecasignalview -f:32,12,44100 jack_alsa jack_alsa
> 

Ok, thanks.  I didn't know about that.  Especially helful because
I have no audible output from my RME, it's just connected to the
AW4416 and nothing else.  To hear what I've transferred, I have to
restart JACK to use my audigy2.  Being able to see some feed back
during the transfer would help a lot.

> ... and do use also other tools (like 'timemachine') to make sure the 
> problem is not in a bad installation/bug in ecasound.

Oooh, timemachine looks interesting.  Thanks.

> 
> > This works, but it seems small sections of the audio are
> > being dropped here and there, so the result is that the
> > transferred data is mostly correct, but is kind of "jumpy"
> > as it skips these apparently dropped sections, which are
> > short, but definitely noticeable.  I suppose it could be
> > some issue with my OS, scheduling, etc., or possibly
> > cable problems.  That latter I can rule out by moving
> > my computer, and using different, shorter cables, I guess.
> 
> My first guess this is trouble with the JACK settings (too low latency 
> settings for your current system and how it is configured). I'd recommend 
> trying witCh slightly larger settings of jackd period size and retry
> the tests. Simply connect your soundcard inputs back to its outputs with 
> qjackctl and verify that the audio is ok (make sure any analog loopbacks 
> are disabled -> you don't hear any audio from the outputs until you 
> connected them with qjackctl).
> 
> Some tips on how to debug/trace JACK performance can be found for 
> instance at:
> 
> - http://jackaudio.org/faq
> - http://ccrma.stanford.edu/planetccrma/software/installtwosix.html#SECTION000201000000000000000
> 
> -- 
>   links, my public keys, etc at http://eca.cx/kv
> 

Thanks for the tips, this gives me a lot of things to try.

-- steve



 
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