[LAD] First release of zita-ajbridge

[James Warden]

Hi Fons,

I gave it a shot yesterday evening. It was not meant to be a thorough test but just a check whether I could just replace alsa_in/out with zita_a2j/j2a in my environment:

- Core 2 Duo 2 x 2.4GHz (cpufreq disabled)

- kernel 3.2 from liquorix (debian i686) with thread_irq enabled (but no complete preemption patch)
- RME HDSP + Multiface II

- jackd2 (latest from svn, before it got moved to github) running in sync mode, at 96kHz, buffer size 2 x 256 frames 

- zita_a2j running on ALSA loopback (loopback card with only two pcm substreams enabled when loaded to the kernel)

My .asoundrc is described in the unofficial ALSA WIKI page about the loopback device used as a bridge for non-jack apps. I basically set the loopback card h/w and s/w parameters to match my jack setting.

The result is not as good out of the box as with alsa_in. I have a wav file which is a 440Hz signal running for 2mn. When I play it through mplayer -ao alsa and alsa_in on the other end of the ALSA loopback, I get no interruption at all. Your zita_a2j app quickly introduces interruptions (dropouts probably) which happen when it displays something about synchronization in the terminal. I played with the resampling factor but it did not improve anything in terms of dropouts. On the other hand, alsa_in was just fine.


Not sure whether you can use this at all as a data point, but something is not optimally running. I have no time to do more thorough tests.


Cheers!
J.




________________________________
From: Fons Adriaensen <fons at linuxaudio.org>
To: Linux Audio Users <linux-audio-user at lists.linuxaudio.org>; Linux Audio Developers <linux-audio-dev at lists.linuxaudio.org> 
Sent: Sunday, March 18, 2012 10:22 PM
Subject: [LAD] First release of zita-ajbridge

Hello all,

The first official release of zita-ajbridge is now available at
<http://kokkinizita.linuxaudio.org/linuxaudio/downloads>.

Quoting the README:

This package provides two applications, zita-a2j and zita-j2a.
They allow to use an ALSA device as a Jack client, to provide
additional capture (a2j) or playback (j2a) channels. 
Functionally these are equivalent to the alsa_in and alsa_out
clients that come with Jack, but they provide much better audio
quality. The resampling ratio will typically be stable within
1 PPM and change only very smoothly. Delay will be stable as
well even under worse case conditions, e.g. the Jack client
running near the end of the cycle.

You will also need the latest zita-resampler and zita-alsa-pcmi
libraries.

All feedback welcome.

Ciao,

-- 
FA

Vor uns liegt ein weites Tal, die Sonne scheint - ein Glitzerstrahl.

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