Re: [LAD] First release of zita-ajbridge

Le 19 mars 2012 à 15:20, Fons Adriaensen a écrit :

> On Mon, Mar 19, 2012 at 01:19:25PM +0100, Stéphane Letz wrote:
>
>> I'm wondering how your code could replace the "adapter" mechanism that I did in JACK2 for that never worked fully reliably. Basically the "adapter" idea is a bit more general in the sense that it aims at "adapting" streams in different context: like network <==> Audio API (CoreAudio for OSX, ALSA for Linux, PortAudio for Windows...), or several ALSA devices..etc..
>> (The adapters are also developed as "in server" clients, this make a bit more easy to add them in a running session using "ladish" kind of studio management approaches...)
>
>> How complex do you think it would be?
>
> I'd never consider writing a2j and j2a as 'in-server' clients, they are far
> too complex for that. An 'in-server' client should be so simple that there is
> essentially no risk that it could ever malfunction and take the entire server
> down. As as long as it does simple audio processing that can probably be the
> case (but even that isn't given - consider an app sending Nans and Infs to
> an internal client).
>
> Apart from Jack's thread, a2j and j2a have two other threads. One runs at
> a higher priority than Jack (reading and writing the ALSA device), the
> second is the 'main event loop', ATM only providing text output to the user,
> but I'm considering GUI versions as well. There is also some non-trivial
> state management involving messages between these threads - required mainly
> to recover cleanly from anything that disrupts regular period timing, xruns,
> skipped cycles, freewheeling, etc.
>
> So the idea of making these 'in-server' was rejected quite early, also
> because really nothing is gained by it.

Well I think it does in some cases, and basically when controlled by the so called "Control API"

>
> Also, apps like these are 'fixed infrastructure', not something managed
> on project/session level. In my 'ideal world' they would run as system
> daemons, as would Jack itself.
>
> What would be an interesting addition to Jack would be the possibility
> to reduce the timing uncertainty for certain clients. At the moment
> a client can run anywhere between the start of a cycle and the start
> of the next one - no assumptions can be made. If a2j would always
> run near the start of a cycle, and j2a never before e.g. 90% of the
> cycle has passed, that would enable to reduce the minimum required
> latency.

Do you mean having the sever "decide" to run a2j/j2a before others in a given cycle?

>
>
> Network versions (j2n and n2j) are in development. They are meant for
> use on a LAN (not for the Internet at large). They use multicasting,
> so you can e.g. distribute an audio signal to all machines in a lab
> or classroom. Resampling is done by the receiver(s). I'll be doing a
> real-life test in a few weeks, recording a concert in the CdS auditorium.
> Eight mic signals will be sent by j2n connected to the nearest network
> rack, from there using optical links to another network rack, and from
> there to n2j running in the LABEL studio.
>
> Ciao,
>
Well so now we are on the road for "another" netjack like application...;

I'll still interested to see if your code can be used for the adapters, since it makes sense on others platforms than Linux.

Stéphane

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Received on Mon Mar 19 16:15:03 2012