[LAU] Zita-ajbridge ?

[Marc Lavallée]

Fons Adriaensen <fons at linuxaudio.org> a écrit :
> I mean: there is no need to resample if you want to use mplayer with
> Jack. If the audio file's sample rate doesn't match that of Jack,
> mplayer will do the resampling.

Mmhh... I'd prefer everything in 24bit until the output to alsa; I
don't want to provide 16bit channels to ambdec from 24bit amb files.
But then, is it a valid concern? I have the feeling that it doesn't
matter much...

> Start Jack with two playback channels, and any program having at least
> four jack inputs, e.g. ambdec. Then try
> 
>   mplayer -ao jack:port=ambdec -channels 4 YOUR_4_CH_FILE
> 
> and mplayer will have four output ports and connect them to ambdec's
> inputs, even if your sound card has only two outputs.

It works as you described. 

> The real problem is that mplayer doesn't allow you to specify the
> connections, they could be in any order. So chances are 1 in 24 that
> they will be correct in this case. Mplayer is one of the many apps
> that claim Jack support but get it all wrong.

For FOA, mapping of amb files is WXYZ, while ambdec inputs are
0w,1y,1z,1x (why?), so the connections are wrong (W-0w,X-1y,Y-1z,Z-1x).
Here's how I remapped the outputs:

mplayer -loop 0 -channels 4 -af channels=4:4:0:0:1:3:2:1:3:2 -ao
jack:port=ambdec AJH_eight-positions.amb

I will write a script to support other amb channels mapping with
mplayer (up to fff in Malham notation).

Now my problem is to connect mplayer to a second instance of ambdec; I
need it for lower frequencies, and since I use a triangle (for basic
horizontal decoding), I had to change the lower limit for the number of
allowed channels in the  source code of ambdec.

> > - I installed the latest Jackd (version 1.9.10 from Grame):
> > zita-j2a now works! :) 
> 
> What was your previous Jack version ?

Version 0.121. It was kept on my system by some old software. I
uninstalled all software with dependencies to Jack, then I was able to
install a newer version of Jack.

> >   after the "Starting synchronisation" message, there's now a
> >   continuous sequence of numbers.
> 
> Probably because you still use -v. See the README for what they mean.

Yes, it's useful to verify if it works.

> > Suggestion: a note in the documentation about the version of
> > Jackd would help.
> 
> It shouldn't matter, unless it's *very* old. Zita-ajbridge requires
> nothing special from Jack, apart from a working DLL. And that was
> added at least five years ago.

Ubuntu is still providing version 0.121, even in the newest development
distribution (saucy), probably for compatibility issues.

--
Marc