[wdmaudiodev] Re: USB2.0 High speed audio device for windows XP
- From: <carsten_30_@xxxxxx>
- To: <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Wed, 20 Feb 2008 19:08:05 +0100
Hi Tim,
if you remember my first question, it was: "How can i make avssamp appear as
a system audio device, because I want to develop a kernel streaming driver
(based on avssamp) wich deals with my USB2.0 audio device. But all trys to
access this WDM KS driver as a system audio device fail. Waht must I do?
Change topology, AddInterfaces in the inf, what is the way?" Your answer
was(and sounds like an accusation): "May I ask why you are not using
usbaudio.sys? I cannot imagine anyone in the last 5 years who would have
designed a USB-based audio device
that was not USB Audio Class compliant."
What should I say? You can not imagine anyone in the last 5 years, who needs
USB2.0 bandwidth with audio!!! But I do! And for me is usbaudio.sys
useless!!! But, by the way, I have learned a lot about MS-Audio in the the
last two weeks. But the more I know the more and more confusing became
usbaudio.sys. here are some examples:
If I report more than one sample rate in the Class Specific Audio Streaming
Interface Descriptor,like this
;; class specific Audio Streaming interface Descriptor
db 7 ;; length
db CS_INTERFACE ;; Type
db GENERAL ;; Sub type
db 2 ;; bTerminalLink (ID of Output Terminal)
db 1 ;; bDelay
dwi 1 ;; wFormat (PCM=0001)
;; FormatDescriptor
db 0BH ;; length
db CS_INTERFACE ;; Descriptor type
db FORMAT_TYPE ;; Sub Type (Format_Type)
db FORMAT_TYPE_I ;;
db NumChannels ;; # channels
db 2 ;; byte per subframe
db 16 ;; Bits per Sample
db 2 ;; #frequncies supportred
db 0x80,0xBB,0x00 ;; 48 khz
db 0xF0, 0x55, 0x00 ;; 22 Khz
the device doesn't appear as a system audio device no more.
How will usbaudio.sys select one of the repoerted sample rates (i havn't
found a request for this).
If I report 1 input terminal (line in)and 1 output terminal and connect them
directly, all is fine, device is a system audio device.
If I report 2 input terminals (lines in) and 1 output terminal and connect
them via a selector, the device is accessible via WDM(Graphedit/KsTools
works fine) but no more as system audio device.
Very, very confusing!!!
Carsten
----- Original Message -----
From: "Tim Roberts" <timr@xxxxxxxxx>
To: <wdmaudiodev@xxxxxxxxxxxxx>
Sent: Monday, February 18, 2008 10:20 PM
Subject: [wdmaudiodev] Re: USB2.0 High speed audio device for windows XP
carsten_30_@xxxxxx wrote:
MS UsbAudio.sys is largely useless!!!
That's not at all fair. There are millions of USBAudio devices out there
in the world that are working perfectly fine, and have largely done so
since Windows 98. You can say that it's not state of the art, but that's
a very different complaint.
--
Tim Roberts, timr@xxxxxxxxx
Providenza & Boekelheide, Inc.
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