Record two mono channels simultaneously

[Gale Andrews]

On both Windows and Mac I've been told that if you don't connect all the channels you still have to set Audacity to record the maximum number of channels so it can find the ones you want.

I was under the impression that to use, for example, input 3 of the sound card required recording channels 1, 2 and 3, where "3" is the channel connected to input 3. That would be consistent with how ASIO works.

That would sound logical, and would imply that if you want to record only input (channel) 2 of four, you set Audacity to record 2 channels and not 4 channels. But I've been told even under ASIO that doesn't usually work.

And if for any reason Audacity thinks inputs 3 and 4 are channels 1 and 2, it would not work for that reason.

This is from a number of users who made detailed comments when requesting improved multi-channel recording features. But obviously I have no personal experience.

Gale

[steve]

and would imply that if you want to record only input (channel) 2 of four, you set Audacity to record 2 channels and not 4 channels. But I've been told even under ASIO that doesn't usually work.

A while back I borrowed a 4 channel USB sound card, and that is precisely how it worked with Jack, though with Jack there is the added benefit that you can perform channel mapping outside of Audacity (for example in QjacCtl or Patchage). The only real limitation of working this way with Jack is that Audacity has non-persistent audio ports, so you have to "re-wire" the channel mapping every time you want to record (or set up a dummy device for Audacity to record from).

[cyrano]

I see two "styles" of multichannel interfaces:

- USB audio compliant interfaces just present a number of channels, from 1 to 16. There's no direct monitoring in the interface, nor level control or routing.

- Pro style multichannel interfaces that have their own control panel in the driver or a separate setup application. These usually have direct monitoring, routing and sometimes digital level control. Since you can route every channel to every channel, it's easy. It's controlled outside of the audio recording app, though. Only Avid HD systems and a couple of others have integration for the digital level control for preamp gain from Protools or their accompanying DAW.

I don't see how the basic behaviour is any different between Linux, OSX and Windows. I also have never seen any randomness or inability to save settings

[Gale Andrews]

I don't see how the basic behaviour is any different between Linux, OSX and Windows.

It could be different because the API's are different. A lot of our Windows users recording multi-channel are not using ASIO because Audacity has to be compiled to provide ASIO support. So they are relying on E-WDM drivers under Windows DirectSound host or WDM-KS drivers under WDM-KS host.

And there may be quirks in our ASIO support, which because little used, gets little attention.

I also have never seen any randomness or inability to save settings

This is on Mac? And you find for a "simple" USB interface without routing that if you want to record channel 5 and 6 of 16, telling Audacity to record six channels always works?

Gale

[cyrano]

I also have never seen any randomness or inability to save settings

This is on Mac? And you find for a "simple" USB interface without routing that if you want to record channel 5 and 6 of 16, telling Audacity to record six channels always works?

Gale

It's like that since OS 4.2 at least

But yes, that's on Mavericks, currently. And the channels are always in the exact same order. No randomness. I've also used these interfaces with Debian, long ago when the firmware loader was still available in the distro's repo's and haven't seen any randomness either. And I can't get the firmware loader to work with a Raspberry, since it's X86 code and not ARM. No other Debian devices here today that could use audio.

I don't have a class compliant interface with more than 6 inputs, but yes, basically it works every time. I used to have a Zoom R16 and when used as an interface, it was the same thing. And I install bigger interfaces for people I support quite regularly.

As a test, a while back, I've recorded 16 channels with the RME and an older Audacity on an older Powerbook with a G4 processor and Tiger (10.4.11). It works exactly the same as under Mavericks.

But the RME is a bad example in this case, it allows to route any channel to any channel in the Totalmix software, which is an almost a complete daw of it's own. In case of RME the complete config can be saved to the device. Even if you plug into another computer, your settings are there and can be recalled at will.

I think the main problem with Windows is that there are some crap interfaces around. That's certainly not Microsoft's fault, but it makes it very hard for the user to buy something decent. The only thing I really don't understand is their lousy support for audio class compliant devices. They can do it, they just won't...