Remote sound device inputs to a master machine

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unaHm
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Remote sound device inputs to a master machine

Post by unaHm »

Recently, I've fallen down the rabbit hole of networked audio components. It all started from a relatively innocuous Google search for "Linux AVB", and then I got excited as I read some threads on the official Ardour forum:

https://discourse.ardour.org/t/dante-pr ... udio/89782

and

https://discourse.ardour.org/t/linux-avb-support/89168

I also found this thread of Frank's to be quite interesting:

viewtopic.php?f=27&t=14159

So I fired up an old PC that I have, put Ubuntu Server on it, installed Jackd2, and fiddled around. I was most successful with the zita-njbridge method
(the netjack2 method ended up falling behind) of connecting, although I must admit I'm going through a switch, and my ideal situation would be a direct cable between the two machines.

My goal is to use the 'remote' machine as a way of carrying audio signals from an interface to my master machine. Most of my audio interfaces are USB, and so I've found in my experience that I need to keep the cables short to save on dropouts, which is less than practical.

I still couldn't really get the latency down to where if I played (my Bass) through the AD interface there was no noticeable delay in the output sound. I suppose I could 'monitor' what I'm playing from the device itself (a Zoom B3) while I'm recording, but I wanted to embark on a 'low latency exercise' to see what really can be done :)

So, for those experienced in this realm:
1. What is the most successful software setup used to get audio channels over the network?
2. Is Jack necessary for this task, or is there a way to do this at the ALSA level? (I did think about sending audio with netcat, but from what I've read it doesn't really do well in terms of latency)
3. Is there anything obvious that I'm missing (e.g. a newer session/connection manager) that can do all of the work for us?

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bluebell
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Re: Remote sound device inputs to a master machine

Post by bluebell »

I think the main problem for a jack based solution is having 2 interfaces: one on the remote machine and one on the main machine for monitoring. Having 2 interfaces that are not synced (wordclock or similar) means that one of them has to run asynchronously.

There are many solutions and none is satisfying.

I am afraid the best affordable solution is someting like MOTU UltraLite AVB on your master machine and an AVB equipped preamp that's connected with an enternet cable.

But AFAIU you need an AVB capable network switch as well, at least when you want to access the MOTU's builtin mixer.

Code: Select all

Preamp -- AVB switch -- MOTU 
           ETH |          | USB 
               +------ PC-+
Linux – MOTU UltraLite AVB – Qtractor – https://soundcloud.com/suedwestlicht

unaHm
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Re: Remote sound device inputs to a master machine

Post by unaHm »

bluebell wrote:I think the main problem for a jack based solution is having 2 interfaces: one on the remote machine and one on the main machine for monitoring. Having 2 interfaces that are not synced (wordclock or similar) means that one of them has to run asynchronously.
Agreed. I think that's where I've seen first-hand at the point where the dropouts occur. I still haven't tried the netone driver, or JACK 1 at this stage, so there might be room for improvement in the use case I have!
bluebell wrote:There are many solutions and none is satisfying.
It's a shame...Linux needs its own form of AES ;)
bluebell wrote:I am afraid the best affordable solution is someting like MOTU UltraLite AVB on your master machine and an AVB equipped preamp that's connected with an enternet cable.

But AFAIU you need an AVB capable network switch as well, at least when you want to access the MOTU's builtin mixer.

Code: Select all

Preamp -- AVB switch -- MOTU 
           ETH |          | USB 
               +------ PC-+
I think I'd seen your example of this in an earlier thread while I was searching around, and it makes sense. It's unfortunate that the computer is linked into the AVB network via USB, but it's also good that MOTU have essentially provided a gateway to AVB for Linux users.

For my own use case, I was able to dig out an oldish PCI soundcard that I've been able to run at really low buffer sizes, even at 96kHz, while under a good deal of load. I suppose I could use that in my 'main machine', and then work on the 'network satellites' with the USB interfaces set at feasible values (with short cables, I can get the buffer sizes rather low there too).

Has anyone had any experience with Roc ( https://github.com/roc-project/roc )? I'm tempted to try it out.

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bluebell
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Re: Remote sound device inputs to a master machine

Post by bluebell »

In my example the Linux computer is connected to the MOTU via USB (für audio) and via Ethernet (to control the MOTU's mixer).

I read that other OS' can use TCP/IP on the USB connection as well, so maybe Linux can do it as well. Never tried. Thenn you should setup the MOTU with a fixed ip address or run a DHCP server on the Linux computer on the USB interface. Could be more or less fun :mrgreen:
Linux – MOTU UltraLite AVB – Qtractor – https://soundcloud.com/suedwestlicht

merlyn
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Re: Remote sound device inputs to a master machine

Post by merlyn »

I was under the impression from reading other threads that @Drumfix had written a Linux AVB driver.

I like the idea of audio going into my computer over a network cable -- that seems like the way things should go.

@bluebell : have you tried this? Or do you have an idea if it works?

unaHm
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Re: Remote sound device inputs to a master machine

Post by unaHm »

I'm going to try out one of the devices from Hasseb, as they're within my price range, and they have a built-in web interface for managing the signal flow (apparently that's the crux of the matter for AVB/AES67).

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