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

David Santamauro david.santamauro at gmail.com
Wed Jan 1 11:13:29 PST 2014

On 01/01/2014 01:19 PM, Jörn Nettingsmeier wrote:
> 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
> problem.

it's actually 4 midi ports * (approximately) 16 channels, so 64 midi 
streams as well (only master -> slave).

>>>> 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?

yes, but the windows side didn't complain.

>>>>    - 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.

currently it is for "live" sequencing but I'd ultimately like to find a 
score editor that could handle the 8-port/64 midi-out channels so I 
don't have to record it.

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

what's the difference?

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