[wdmaudiodev] Re: USB2.0 High speed audio device for windows XP
- From: Hakon Strande <hakons@xxxxxxxxxxxxxxxxxxxxx>
- To: "wdmaudiodev@xxxxxxxxxxxxx" <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Mon, 18 Feb 2008 13:20:02 -0800
Sorry to hear you have given up on USB Audio. Maybe you will re-evaluate when
USB Audio 2.0 is mainstream in a few years.
To comment on your feedback:
USB 1.1/USB Audio 1.0 with its limited bandwidth and the native Windows USB
Audio 1.0 class driver is a relevant combination for scenarios you may not care
about, such as voice communication and music/move entertainment. The USB Audio
class driver in Windows supports common multi-channel formats both for
microphone arrays on the input side and multi-channel speaker setups on the
output side.
So for a lot of common audio streaming scenarios the USB Audio class driver is
perfectly adequate but I agree that pro-audio content creation scenarios have
requirements that are not necessarily met by the current USB Audio class
driver. It is certainly not useless though. :-)
ASIO is a 3rd party app-to-driver streaming protocol much like Microsoft
DirectKS on XP or Windows Audio Session API (WASAPI) on Vista. Our class
drivers do not support ASIO since ASIO is a 3rd party technology. If there was
a Windows USB Audio 2.0 class driver and your application used ASIO as a
streaming protocol instead of Windows native APIs such as WASAPI you would
still need a proprietary ASIO driver unless you use some of the new ASIO on
DirectKS implementations I have heard rumors about (ASIOforALL or something
like that).
I totally agree USB Audio 2.0 spec resolves a lot of issues that prevented USB
Audio from adoption in the pro-audio content creation market. I also agree that
a native USB Audio 2.0 class driver in Windows is a no-brainer from the POV of
high end audio content creation. This time it unfortunately lost out to a host
of more consumer oriented feature development.
Hopefully we will be able to develop such a class driver in the not too distant
future but hearing you have given up on it isn't adding a lot of fuel to our
business justification :-).
In any case, stringent IHV spec compliance and close collaboration with
Microsoft when designing new USB Audio 2.0 devices is a great way to help
ensure a future USB Audio 2.0 class driver for Windows. If spec interpretation
issues and fragmented implementations with "special" per-IHV HW twists/hacks
lead to an ecosystem with devices that can't be easily supported by a class
driver without device specific code hacks a Microsoft investment in a USB Audio
2.0 class driver is less likely.
BTW, Windows does not have a native 1394 audio class driver either so I am not
sure what moving to 1394 buys you unless there is better 3rd party driver/Mac
support for that HW technology or there are other reasons for you to use 1394
than USB Audio 2.0 hardware.
Sincerely,
Hakon Strande | Windows Sound Team PM | (p) 425.705.0637
-----Original Message-----
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Al Clark
Sent: Monday, February 18, 2008 12:32 PM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Re: USB2.0 High speed audio device for windows XP
As far as I can tell, USB Audio is largely useless if implemented using
the built in Microsoft drivers. Its basically 48k, 16 bit, 2 channels.
The Audio Device 2.0 standard addresses many of the problems of the
original USB standard but Microsoft has never replaced usbaudio.sys 1.0
Most prosumer gear uses ASIO as a practical workaround. The large audio
companies write custom drivers that they can amortize over many units.
This leaves the rest of the world with no real USB solution at all.
IMHO, Microsoft could solve a lot of problems by implementing a
usbaudio.sys 2.0 driver. It would support the USB Audio Class standard.
It should be implemented in both XP & Vista for it to be useful. Sure
lots of prosumer gear has ASIO support, but lots of other products do not.
A good driver should support multichannel audio with 24 bit depth (and
maybe 32 bit floating point), sampling rates to 192k, low and known
latency, etc.
Our company has given up on USB audio. We are moving to Firewire.
I'm by no means knowledgeable about device drivers. By and large,
neither are my customers. So please don't blast me, if I have my facts
screwed up, instead please enlighten me.
Al Clark
Danville Signal Processing, Inc.
Hakon Strande wrote:
>
> I'll confirm this with engineering but AFAIK the USB Audio 1.0 class
> driver is limited to the bandwidth of USB 1.1 spec - BUT - USB Audio
> 1.0 devices can hook up to a USB 2.0 hub /in the way mentioned below/
> so other devices on that hub (like webcams) can leverage the greater
> bandwidth.
>
> 1) The USB Audio 1.0 device connecting to the USB 2.0 hub must have an
> interval of 4 (interval of 1ms) on the Isoch pipe to match that of USB
> 1.1.
>
> 2) The USB Audio 1.0 device connecting to the USB 2.0 hub cannot be an
> async endpoint (no feedback pipe).
>
> Sincerely,
>
> * *
>
> *Hakon Strande <mailto:HakonS@xxxxxxxxxxxxx>* |* *Windows Sound Team
> PM |* *(p) 425.705.0637
>
> *From:* wdmaudiodev-bounce@xxxxxxxxxxxxx
> [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] *On Behalf Of *Tim Roberts
> *Sent:* Monday, February 18, 2008 11:02 AM
> *To:* wdmaudiodev@xxxxxxxxxxxxx
> *Subject:* [wdmaudiodev] Re: USB2.0 High speed audio device for windows XP
>
> Hakon Strande wrote:
>
> You can connect a USB Audio 1.0 device to a high speed bus (there are
> some tricks to this) but bandwidth use is limited by the USB Audio 1.0
> spec.
>
>
> Where? I've been through the whole USB Audio 1.0 spec, and I don't
> find anything that ties the spec to USB 1.x bandwidth. Indeed, it
> seems to be very careful to avoid making any mention of "low-speed"
> and "full-speed" at all.
>
> --
> Tim Roberts, timr@xxxxxxxxx <mailto:timr@xxxxxxxxx>
> Providenza & Boekelheide, Inc.
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