[PlanetCCRMA] Ardour hardware monitoring

John Yates jyates@hvc.rr.com
Fri May 14 13:00:02 2004


Thanks for your reply. I think this is becoming a little clearer for
me. Unfortunately, I don't think I'll be able to do what I was
hoping to do. I'll try to explain. This may or may not apply to your
hardware and I still may not have it quite right, but here are my
present assumptions.

The RME Digiface, is set up with 26 hardware inputs (24 ADAT, 2 SPDIF),
26 software playback inputs (these are selected in Ardour as if they
were hardware outputs) and 28 actual hardware outputs (24 ADAT,
2 SPDIF, and 2 analog/headphone). Each of the 52 inputs has a level
(fader) send to each of the 28 outputs. Routing (buss connect) changes
never happen since everything is routed everywhere all the time.
This means that there are 1456 virtual faders that control what signals
appear at what outputs and at what level at any given time. Inputs going
into Ardour bypass the mixer and are not level controlled.

Now for hardware monitor switching to occur during a punch in, a
software playback level would have to go down and a hardware input
level would have to go up. At punch out the levels would switch
back again.

Here's the rub. Levels to which output channel? Remember, each input
has 28 possible output 'send' levels. My guess, and I can't test right
now because I'm at work, is that it would be the sends to whatever
hardware output channel is selected in Ardour's mixer strip. This is
probably great if you are using Ardour with an outboard mixer.
However, what if your tracks are not sending to individual hardware
outputs, but rather to an internal Ardour stereo master buss. There
is no selected hardware output to send the input to in this case. Ardour
defaults the output of the master fader to hardware outputs 1 and 2
which in reality means playback inputs 1 and 2 on the hardware mixer.
The levels of these two inputs going to the analog/headphone output are
what I am using for monitoring. Even if Ardour could assume that you
were monitoring via playback inputs 1 and 2, it still wouldn't know
which hardware outputs you were actually listening to in order to
send the hardware input there. And even if you told it explicitly you
would not get whatever level was set for the track in Ardour's mixer.

What I believe all this means is that zero latency hardware monitor
switching for punching into tracks is only valid if you are using an
outboard mixer to get your stereo monitor mix. To achieve what I was
thinking about would require the actual mixing to take place in the
hardware mixer with Ardour simply acting as a controller and this is
not the case.

Sorry, if this was already obvious to everyone. Just trying to get a
handle what's possible with this set up. And please correct me if I am