Ardour live mixing: Backup solution?

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Benjamin Scherrer
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Hi,

ever since I first used a digital live mixing console, I've thought about using my pc and Ardour for live mixing. I'm talking about small to medium sized rock/metal concerts with about 16 tracks. I've got all the necessary hardware (RME HDSP 9652 with a Focusrite Saffire Pro 40 8in/8out + PreSonus Digimax D8 8in) and think that especially a version of Ardour I am not allowed to talk about here right now fits the live mixing situation (PFLs, Sends-on-faders...) perfectly.

My problem: Ardour is software, so I cannot rely 100% on it. It may crash at sometime. Do you have any ideas how to keep the signals on the PA/monitors on stage even in the case that Ardour crashes?

So far, I thought about using my HDSPMixer, setting it up to recreate the volumes that I've configured in Ardour. In the case of an Ardour crash, I could immediately load a preset in the HDSPMixer and at least have the signals without EQs etc. on the PA. In this way, I would have a very small time without sound. Then I'd have time to start Ardour again. I'd be even JACK-independent, only the Linux kernel mustn't quit on me ;)

Does anyone know a smart way to copy volumes from Ardour to the HDSPMixer?

Is there a professional way of doing this? I know that some really big bands use DAWs for live mixing, too.

Thanks!
Benjamin

fernesto
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Hi Benjamin

I've thought about this before as you have but i think the biggest issue is the Low Latency/Stability relationship which is critical for that to work, much more than worrying about Ardour crashing which is also possible, all that will get you to a lot of tweaks to your OS.

Now since crash is always a possibility i would consider managing monitoring through HDSPMixer directly or even your Saffire Pro 40 internal mixer but that leads again to a latency issue since you want the mix running through plugins in Ardour the signal has to come to the PC enter Jack Ardour then Plugins then Jack Again then out, there will be latency compared to the hardware mixing in the Saffire...

I hope you find a way, im insterested also in this topic, i use also a HDSP 9652 and a Saffire Pro 40 and hoping to expand on ADAT preamps soon.

Benjamin Scherrer
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Hi fernesto,

I don't think latency is an issue. I can run jack with 128 samples and have LinuxDSPs Gate, Compressor and EQ on each of the 16 channels plus a reverb channel and graphical EQs here and there (~60 plugins). Ardour's DSP usage is at about 25-30%. I'm using an unpatched vanilla kernel (3.1.4) with an AMD Phenom 4x2,5GHz. I could even go down to 64 samples but I don't think it's necessary for a live performance.

Of course the HDSPMixer has (nearly) no latency, but I wouldn't run them at once, I would only enable the mixer in the case that Ardour crashes to avoid a complete outage of the monitors and PA.. But I would have to copy all levels for a mix by hand... So I'm looking for another solution. I'll tell you when I find one!

Best,
Benjamin

fernesto
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Wow thats a lot! i use a Phenom x3 @ 2.3 Ghz and 4GB Ram at 800Mhz, running Ubuntu 11.10 with low latency kernel but when i go under 512 xruns start to appear from time to time, now i know that ubuntu's unity may be part of the problem, any suggestions to improve my stability?

Benjamin Scherrer
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Maybe we can talk about that on IRC some time, my names usually "roax" there. It depends on various factors, your jack settings, maybe the kernel, cpufreq settings, DSP load, and so on. I'm using debian stable 64bit, Jack 1.9.7, self built kernel (but not patched), and 4GB RAM at 1066 MHz (I don't think the frequency makes a difference here).

linuxdsp
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i know that ubuntu's unity may be part of the problem, any suggestions to improve my stability?

Use a different version of Ubuntu :) I've had nothing but trouble with 11.10 on a few different hardware combinations (and not just with audio) - I now use 10.04LTS which was the last really stable version in my opinion.

projectMalamute
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You don't need to be getting the latencies that low. The FOH should be delayed to the backline anyway, 10 ms latency is just the first 10 feet or so for free.

seablade
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@projectMalamute

It depends. In general if you are mixing, you need latencies as low as you can possibly get. Keep in mind that the latencies reported by Jack are just software latencies, that the actual AD/DA process will induce it's own latencies that the software can't report because there is no way for it to know how long it takes during the AD/DA process. And if you have external gear inserted it can be even more(Or even just plugins for mixing will add latency), and of course speaker processing these days generally happens via DSP so even more.

Not to mention backline isn't the only thing on the stage and in many stages you can have vocalists or lead guitarists under or even in front of the FOH setup, so that they are already ahead of the initial wavefront by a few mS at least. Of course this is before we even consider delay for the front of the audience from speakers being rigged 20 feet in the air compared to the singer right in front of them.

So in short, the lower the latency the better when dealing with live situations. While your basic premise might be correct, in general it doesn't hold up well when considered with everything else going on.

Seablade

Avoiding a discussion of the implications of the Haas effect for imaging etc. for the moment as most people don't work in theater and the like where it becomes especially important.

Benjamin Scherrer
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Thanks for all the input about latency... but this thread was actually started to discuss the stability of a live mixing situation and how to attain a back up solution for a crash of the DAW. Any thoughts about this?

linuxdsp
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There is no simple answer regarding a failsafe backup system for live mixing - if you use a digital system - any digital system - there is the possibility it can crash at some point. I've had experience of this with extremely expensive pro equipment, specifically engineered for live / broadcast, equipped with numerous redundant systems, and it seems that if something is going to go wrong it will always seek out whatever single point of failure exists in the system (and choose the worst possible time to happen). The 'safest' way is to have an analogue backup of some kind, although this is a non-trivial thing to arrange (and although analogue systems do fail, it's less common for a failure to take out the entire system, as would be the case with a computer crash). Professional live digital systems often have multiple backup computers as well as backup power supplies, etc etc. Its difficult to recommend a specific setup / analogue backup configuration as this depends on the complexity of the live mix, PA system, stage monitor systems etc etc.
What you definitely don't want is a crash which leaves you with audio doing things over which you have no control, or full-scale digital noise (I've also experienced both these situations and its not nice). You need to consider very carefully the risks involved against the possible benefits (remember that it's not just a crash / reboot but also rogue plugins etc - which may even cause you worse problems)

Benjamin Scherrer
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Thanks for your input, LinuxDSP!

I am aware that there is no bulletproof backup, except maybe the analog way, which is too costly/time consuming for me.

About your worst case scenarios: I would definitely have a hardware switch ready with which I can silence everything at once, and maybe some limiters etc. And fortunately I'll be using mainly, if not only, LinuxDSP plugins which have always been nice to me :) They don't go rogue ;) I know there's no guarantee, but I would obviously stick too a good tested little collection of plugin like 2-3 EQs, 1-2 compressors, 1 gate, 1-2 reverbs and then use them multiple times.

So I think there is this worst case scenario with which I think I can deal to some extend (it's always a risk, I know) and the more common scenario where Ardour simply crashes and leaves me with no audio at all. I thought I could deal with this by using the HDSPMixer, but it might not be the best way. I'll think about the backup computer way... But the switching should be real fast... I'll come back when I've thought about it (hopefully I'll do come back ;) ).

Benjamin