[Portaudio] Enumerating audio devices (cards and chipsets)

Ross Bencina rossb-lists at audiomulch.com
Mon Mar 7 18:52:49 EST 2011


Okay, I hadn't really understood that you're using JACK on top of PortAudo 
(I didn't even realise there was a working version of JACK for Windows). If 
I now understand correctly, things look like this:

Ardour -> JACK -> PortAudio

If that's the case, any problems you have are just as likely to exist in 
JACK as in PortAudio and you should probably be talking to the JACK guys 
about it. Any fixes are just as likely to be required in JACK as in PA.

As Stephane said, you should be building JACK from source to make sure 
you're using the same version of PortAudio that we're talking about (ie 
current trunk).

AudioMulch doesn't use JACK at all so in effect, you're telling us about 
differences between JACK and PortAudio behavior.

I don't know how JACK works on Windows, but I imagine a lot of Windows users 
would prefer their DAW talked direct to the ASIO driver rather than 
introduced additional overhead with JACK. RME already have IAC capabilities 
in their ASIO drivers for example.


John Emmas wrote:
> On the old machine I can run either Linux or Windows.  Booting up into 
> Linux (using Jack and ALSA as my backend) I see two hardware devices 
> listed:- RME Hammerfall HDSP 9632 and my onboard VIA 8235.  If I select 
> the VIA 8235 in Ardour and then try to route some I/O, I see 2 available 
> inputs and 2 outputs - exactly what I'd expect from an onboard sound chip. 
> OTOH when I select my HDSP 9632 I see 12 inputs available and 12 outputs.
> Now I re-boot into Windows on the same machine and run Ardour again (this 
> time with Jack & Portaudio serving the backend).  Remember that at this 
> stage I'm not selecting any specific sound card because I haven't yet 
> figured out how to do that (or even if it's possible with Portaudio). 
> However, with the same physical hardware I see two inputs and 8 outputs 
> (from the Jack/Portaudio combination) as opposed to 12 inputs and 12 
> outputs from the Jack/ALSA combination.  AudioMulch (on Windows) also 
> shows me 12 ins and 12 outs for my HDSP 9632 card.  I'm sure this anomaly 
> will make sense to you guys but I'm not quite seeing it at the moment. 
> Neither of my interfaces (nor any combination of them) has 2 inputs and 8 
> outputs AFAICT.  I need to investigate this further but I just wondered if 
> you might be able to suggest something obvious that I might be 
> misunderstanding?  Clearly I'm seeing more outputs than are available from 
> my onboard sound chip - but I'm not getting the right numbe
> r for my sound card???

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