[Ardour-Users] very big latencies..

Paul Davis paul at linuxaudiosystems.com
Mon Mar 16 07:18:07 PDT 2009

On Mon, Mar 16, 2009 at 3:32 AM, John Emmas <johne53 at tiscali.co.uk> wrote:

> ----- Original Message ----- From: "Sampsa Riikonen"
> Subject: Re: [Ardour-Users] very big latencies..
>> I installed v. 0.116.2 using subversion..
>> Now it seems I am getting dependency-hell.. :(
>> Now jack says when I start ardour:
>> JACK protocol mismatch (22 vs 24)
>> cannot complete client connection process
>> I hope I can uninstall that new version I just installed..!
>>  Assuming you're building Ardour from source, did you remember to rebuild
> Ardour after you upgraded Jack?  Ardour links to libjack so if the
> connection protocol has changed you'll need to rebuild Ardour (likewise,
> anything else that you build from source that links to libjack).

this is absolutely not true.

there is never any need to recompile applications that use JACK when the
client/server communication protocol changes. the client has no control over
the protocol, it does not dictate which version is used, etc. etc. this
assumes that the client uses shared linkage, which AFAIK just about
everybody does (partly for this very reason).

there is a need to recompile them when the client-side API changes. but this
hardly ever happens. for example, the relatively recent changes that were
made to fix support for mixed 32/64 bit host & clients altered the data
structures internal to JACK in quite fundamental ways. however, it had
absolutely no effect on the public data structures of the API and thus no
client needed recompilation.

it has been sometime since recompilation was necessary. i am not sure quite
how long, but i believe more than a year.

> Essentially, what's happened is that jack 0.116.2 is using a newer protocol
> (24) but Ardour isn't aware of that and is still trying to connect using an
> earlier protocol (22).

if ardour uses shared linkage to libjack, it will be using whatever version
of the client/server protocol is present in the library discovered at
runtime. if the library is the correct version (w.r.t. the server), things
work, and this is the case where you have a single, correctly installed
version of JACK. if you have multiple versions of the library and/or the
server, there is obviously potential for version mismatching, and thats when
you can see this error.

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