Re: [LAU] I just don't know Jack anymore.

On Sun, Jun 06, 2010 at 03:11:05PM -0500, Gabriel M. Beddingfield wrote:
>
>
> On Sun, 6 Jun 2010, Ken Restivo wrote:
>
>>> Jack+Debian: This situation will be improving. Probably won't be in
>>> time for squeeze, though. Not a simple problem to fix, though... because
>>> applications have to link to /something/ -- and the library follows the
>>> jackd implementation.
>>>
>>
>> Wait, what? All the apps have to be recompiled in order to switch jack
>> implementations?
>
> No, they don't have to be recompiled.
>
> From a packaging point-of-view, that's what makes it so hard. I'm not at
> all an expert on the subject, but the confusion goes something like this:
>
> Package `cool_tracker` requires `libjack0`
>
> `libjack0` is supplied by Jack1 _and_ Jack2. If you switch jackd's, you
> have to switch libjack0. So, then you get something like:
>
> libjack0-jack1 (provides libjack0)
> libjack0-jack2 (provides libjack0)
>
> Suppose user does:
>
> $ apt-get cool_tracker
>
> Now, which one gets installed by default?
>
> And when a someone packages `cool_tracker`
>
> $ gcc -o cool_tracker `pkg-config --cflags --libs jack` cool_tracker.c
>
> Then cool_tracker has a link to /usr/lib/libjack.so.0
>
> So... you have to make sure that the .deb package says it needs the
> virtual libjack0 package instead of libjack0-jack2 (which is what the
> packager has installed).
>
> THEN, you run into ABI issues between Jack1 and Jack2. Theoretically,
> there should be none -- but last I check, Jack2 is missing some of
> Jack1's symbols.
>

OK thanks. My apologies for making you rehash stuff that has probably been flying around on the jack list for a while.

Still, the average, non-jack-developers-mailing-list-following linux audio user should be spared from having to know all this stuff, and hopefully the various jack-flavor maintainers and distro maintainers are all working together to make this usable.

Still, if ABI compatibility isn't there, this feels kind of dangerous and could get very ugly.

I now see why so many people reflexively advise anyone having any trouble with linux audio to just get a livecd of a different distro and try that instead. If ABI's aren't compatible between the different jack's, then task of setting up linux audio with jack will fall out of the hands of most users and onto those who maintain custom, mutually-incompatible distros instead. Possibly not a bad thing, and we might be there already as people seek out pre-compiled RT kernels, but perhaps pushing linux audio even farther into custom purpose-built distros might have unintended consequences.

-ken
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Received on Mon Jun 7 04:15:02 2010