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

[Thomas Brand]

On Tue, January 24, 2017 17:13, Jörg Müller wrote:
> Thanks for the information.
>
>
> The two MADI FX cards I'm using can be synced via word clock.
>
>
> However, the information needs to be unaltered, no resampling or any
> modification is allowed for our processing. What command line settings do
> I
> have to use to make sure of that? How can I use the official zita-ajbridge
>  or is there some documentation about it?
>
yes; man zita-n2j

in a nutshell, for two local JACK servers:
main server (default):
jackd -R -d...
zita-j2n --float 10.10.10.19 4445
zita-n2j --buf 0 10.10.10.19 6667

second server (foo):
jackd --name foo ...
JACK_DEFAULT_SERVER=foo zita-n2j --buff 0 10.10.10.19 4445
JACK_DEFAULT_SERVER=foo zita-j2n --float 10.10.10.19 6667

This creates 4 clients in 2 JACK servers ready to be connected in both
directions, for 2 channels (default setting) using MTU of 1500 (default
setting). The delay is constant from what i see in a scope.
10.10.10.19 is the IP address of the local network interface (127.0.0.1 or
localhost should work too).
You still have to find in man page of a recent zita-n2j how to turn off
resampling and set channel counts.

Good luck,
Thomas

> 2017-01-24 16:36 GMT+01:00 Thomas Brand <tom at trellis.ch>:
>
>
>> On Tue, January 24, 2017 16:27, Thomas Brand wrote:
>>
>>> On Tue, January 24, 2017 09:22, Ralf Mardorf wrote:
>>>
>>>
>>>> On Tue, 24 Jan 2017 07:41:50 +0000, j at jrigg.co.uk wrote:
>>>>
>>>>
>>>>
>>>>> On Mon, Jan 23, 2017 at 05:35:57PM +0000, Fons Adriaensen wrote:
>>>>>
>>>>>
>>>>>
>>>>>> With the official zita-ajbridge you can disable resampling.
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>> Good to know.
>>>>>
>>>>>
>>>>>
>>>>
>>>> Could this be used without word clock, by using a digital interface
>>>> to sync, e.g. S/PDIF? If so, assuming two identical cards would be
>>>> used, would sync be hat good, that each combination of IOs, e.g. a
>>>> channel from one card for the left and of the other card for the
>>>> right channel of a stereo signal, wouldn't cause phasing issues?
>>>>
>>> yes i think that works pretty good (drawing from earlier
>>> experiments). Using S/PDIF just for sync is a cheap alternative to a
>>> "real" wordclock.
>>> One of both interfaces will be slaved to the other and then both
>>> should run the same cycle at the same time (so theoretically no
>>> phasing issues). You just have to manage to shove forth and back the
>>> sample data from/to interface at good enough rate which isn't a
>>> particular problem on
>> localhost
>>> using UDP like zita does. If there is no resampling involved, this
>>> can work for many many channels without hitting the CPU too much.
>>>
>>> Greetings
>>> Thomas
>>>
>>>
>> Even if the interfaces are synchronized with S/PDIF, there will be some
>>  cycles (hopefully a static number) needed to shove data forth and
>> back. This needs to be considered to effectively get synchronous
>> behaviour for input or output to both interfaces.
>>
>>
>>
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>>
>>
>