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

[Markus Seeber]

Did you synchronnize the cards via WordClock? Because if you did not,
you will inevitably run into issues due to clock drift.

On 08/02/2017 05:56 PM, Jörg Müller wrote:
> This is months old, but I have news to this topic.
>
> The suggested changes work and we have set up 11x16channel audio
> monitors. That is 176 speakers!
>
> However, running Jack is highly unstable, it crashes roughly every two
> minutes and causes a huge amount of XRuns even at buffer sizes like
> 16000. CPU is down at 5%, so that is not the issue. Jack runs without a
> problem when using just one card. However, we need to combine the three
> MADI-Cards via .asoundrc in order to eventually get to 768 channels.
>
> I have the jack logs here: https://pastebin.com/ke25cdXB
>
> Do you have any idea what could cause the issue?
>
> Best, Jörg
>
>
> Am 10.02.2017 um 14:15 schrieb Adrian Knoth:
>> 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),
>> PORT_NUM_FOR_CLIENT
>>
>> That should be it.
>>
>> Play a bit so it matches your setup. Feel free to send a patch.
>>
>>
>>
>> HTH
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