[wdmaudiodev] Re: best approach to pro audio i/o on a PC

  • From: "Mike Kemp" <mjk@xxxxxxxxxxxx>
  • To: <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Fri, 28 Aug 2015 15:13:51 +0100

Thanks Jerry

Very useful information. It would be easy to make my hardware present itself with a user selectable choice of USB configurations, to match Windows or OSX.

Latency is always an issue, but I know from previous USB drivers I've written that it is hard to get it good, without increasingly risky tricks that tax the non-real time OSes. Your observation is useful info.

I'm pleased you say that the signing procedure is not so much a problem as I've heard a lot of moaning from developers. I know that for Windows 10 you need an EV certificate (~1000 USD) and that it has to be uploaded to MS for signing, even without going the WHQL route. That's in addition to any signing needed for pre Windows 10 versions.

Best regards

Mike

----- Original Message ----- From: Jerry Evans
To: wdmaudiodev@xxxxxxxxxxxxx
Sent: Friday, August 28, 2015 12:47 PM
Subject: [wdmaudiodev] Re: best approach to pro audio i/o on a PC


Hi Mike

Thanks for any suggestions, or pointers to where to go to find the
information I need...

Not sure if latency and/or sync are issues for you.

The in-box Windows 7 USB audio drivers worked perfectly well with up to 48
channels of USB audio, tested with ARM M4 dev boards built some time back.
Data streamed into consumer DAWs (Sonar/Tracktion) with ~8-10ms latency
which was about as low as I'd expected to be possible. ASIO could in theory
be lower.

If you are planning a custom control panel app, then a composite device
(audio+HID for example) will provide a simple, driverless, control interface
as well.

The 800 pound gorilla in the room is, of course, USB audio 2 (UAC2) support.
If your device is going to play nice with Apple products you will need to
have device-side firmware that can switch between the two interfaces.
Multi-channel high speed (48Mbs) USB audio devices that implement UAC1 are
*not* supported by Apple. Sadly UAC2 *not* supported by Microsoft. (ahem)

There are third parties who can supply UAC2 drivers for Windows - thesycon
for example (disclaimer: I have zero connection with these guys)

Incidentally signing etc. is painless these days if you've got a properly
configured VS2013/2015 rig. Truly marvellous. WHQL remains another issue
entirely :)

HTH

Jerry




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