[Ardour-Users] ardour3, netjack, bandwidth, xruns

Jörn Nettingsmeier nettings at stackingdwarves.net
Wed Jan 1 10:19:01 PST 2014

On 01/01/2014 05:35 PM, David Santamauro wrote:

>> can you describe what you are trying to do? why do you think you need
>> two machines for this task? is the extra complication really necessary
>> for the intended job?
> Trying to use windows orchestral VSTi(s) whose required 'dongle' is on a
> windows machine.
>    ardour3:midi-track-1 => slave:midi-input-1
>    slave:audio-out-1    => ardour3:audio-track-in-1
>    slave:audio-out-2    => ardour3:audio-track-in-2
> Pretty simple, actually, but I'd like 48 channels of audio to come back
> from the slave.

interesting use case. so one midi out, 48ch audio in. should not be a 

>>> ardour3 does take CPU slices but the master load avg is ~ 85% idle and
>>> DSP load < 20%.
>>> Viewing network traffic using iptraf, I see total usage in the 45Mb/s
>>> (4% utilization) range for both master and slave -- clearly room to
>>> spare so I'm assuming there is some other bottleneck somewhere.
>>> There are no xruns on the slave.
>> just to make sure: only the master has an actual audio interface, and
>> the slave's timing comes from netjack2?
> :) no sound card on the slave, backend is 'net'

i haven't done serious audio on windows in ages. how does the jack 
driver work? does it pretend to be a virtual asio device?

>>>    - Are there settings (network or for jack_load netmanager) that would
>>> help this situation?
>> bigger period size, bigger network packets. for many channels, you might
>> want to make sure both ends can use jumbo frames, and of course check
>> that there is no MTU bottleneck in between (the switch would have to
>> support them as well, fragmentation is deadly for these workloads).
> bigger period size is pretty unworkable with what I'm trying to achieve.
> Top limit is 256. Anything higher and the latency is intolerable.

is this for live playing? if not, you might just increase the period 
size and network buffering, and compensate other tracks on the master 
with delay. just do it anyway, to see if it helps.

you might also try the netone backend (it's what i tried years ago), but 
i'm not sure it's available on windows...

Jörn Nettingsmeier
Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487

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