[Jack-Devel] Cannot combine audio devices with more than 64 channels

Jörg Müller joerg.mueller7744 at gmail.com
Sat Feb 11 13:38:46 CET 2017

Thanks for your help!

Is there some guide to compile jackd2 from source? Here is what I did:
> sudo apt-get build-dep jackd jackd2
> cd /tmp
> apt-get source jackd jackd2
> nano /tmp/jackd2-1.9.10+20140610git97e0e80b~dfsg/common/JackConstants.h

I changed the DRIVER_PORT_NUMBER value and tried to compile it by
> cd /tmp/jackd2-1.9.10+20140610git97e0e80b~dfsg
> dpkg-buildpackage -rfakeroot -uc -b

But I got the following error:

2017-02-10 14:15 GMT+01:00 Adrian Knoth <adi at drcomp.erfurt.thur.de>:
> On 02/08/17 18:16, Jörg Müller wrote:
>> jackd: ../linux/alsa/JackAlsaDriver.cpp:122: virtual int
>> Jack::JackAlsaDriver::Attach(): Assertion `fCaptureChannels < 256'
>> failed.
>> Aborted (core dumped)
>> The corresponding cpp-file at that line compares against a variable
>> called "DRIVER_PORT_NUM", which is a constant defined in
>> "common/JackConstants.h" on line 53 on the github repo. Could that be
>> the problem?
> That's absolutely the problem, but the limit is arbitrary. Feel free to
> recompile jackd2 with changed constants in JackConstants.h.
> I guess you need to tweak a bunch of other values as well.
> PORT_NUM, PORT_NUM_MAX, DRIVER_PORT_NUM (that's per direction),
> That should be it.
> Play a bit so it matches your setup. Feel free to send a patch.

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