[wdmaudiodev] Re: USB Audio Using Interrupt Transfers

  • From: "vrf" <vrf@xxxxxxxxxxxx>
  • To: <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Fri, 20 Jun 2003 15:14:45 +0800

Dear Udo,

Thank you very much! I am trying it now.
Have you done this or relative job before?

Best Regards!

vrf

----- Original Message -----
From: "Udo Eberhardt" <Udo.Eb@xxxxxxxxxxx>
To: <wdmaudiodev@xxxxxxxxxxxxx>
Sent: Thursday, June 19, 2003 2:38 PM
Subject: [wdmaudiodev] Re: USB Audio Using Interrupt Transfers


> The introductionary article will help you to choose the right driver
model.
> Transferring an audio stream by an interrupt pipe should be possible.
> However, it is somewhat "unusual".
> You need to configure your interrupt endpoint correctly. For example, if
> you set it up with a polling interval of 1 ms and a FIFO size of 8 bytes
> then you will end up with a rate of 8kbytes/s = 64kbits/s.
> Note that you are limited to 64 Bytes FIFO size, means limited to
> 64kbytes/s.
> The priority of interrupt transfers is higher than bulk transfers. The
> host controller will poll an interrupt endpoint once per USB frame, if
> the polling interval is 1 ms.
>
> Udo Eberhardt
> Thesycon GmbH
>
>
> vrf wrote:
> > Dear Udo,
> >
> > Thank you! I will review your introduction.
> > I think I should prefer method one: write My USBAudio.sys。
> > I need 64kbps audio data transfer.
> >
> > Are you sure that interrupt Transfers can implement Isochronous
Transfers?
> > I worry about it because I don't know if the priority of interrupt
transfer
> > is lower than isochronous transfer in streaming driver when the driver
talks
> > to usb device.
> > I am not sure if the steam implementd by this way could be "like"
> > isochronous? :-)
> >
> > Any advices are appreciated!
> >
> > Best Regards!
> >
> > vrf
> >
> > ----- Original Message -----
> > From: "Udo Eberhardt" <Udo.Eb@xxxxxxxxxxx>
> > To: <wdmaudiodev@xxxxxxxxxxxxx>
> > Sent: Wednesday, June 18, 2003 11:58 PM
> > Subject: [wdmaudiodev] Re: USB Audio Using Interrupt Transfers
> >
> >
> >
> >>You have to write a kernel streaming driver that talks to your device in
> >>the way your device supports it.
> >>For an introduction you can refer to
> >>https://www.microsoft.com/whdc/hwdev/tech/audio/wdmaudio.mspx
> >>
> >>Udo Eberhardt
> >>Thesycon GmbH
> >>
> >>
> >>vrf wrote:
> >>
> >>>Dear all,
> >>>
> >>>I have a motorola usb module (MC68HC908JB8/MC68HC08JB8/MC68HC08JT8-Rev.
> >>>2.0).
> >>>Now I need to develop a USB Audio device using it. And the device
should
> >>>be able to be used by Windows Sound Recorder or NetMeeting as a system
> >>>sound device.
> >>>As you know, it only supports interrupt transfers. And it has 3
> >>>endpoints including control endpoint. Endpoint 1 just has input
> >>>direction through which I need to implement a keyboard. Thus ep2 is the
> >>>only choice to transfer audio data. How could I implement my project?
> >>>
> >>>I think there may be two methods:
> >>>
> >>>Method One:
> >>>Describe USB as Audio using interrupt transfers
> >>>then, on Host side
> >>>CreateFile(Open Device)----->My USBAudio.sys
> >>>Method two:
> >>>Describe USB as Audio with Isochronous transfers
> >>>then, on Host side
> >>>CreateFile -----> USBAudio.sys (generic driver supplied by
> >>>Microsoft) -----> My Filter Driver
> >>>Which solution is good, or there is another better one?
> >>>
> >>>Any advices are very appreciated!
> >>>
> >>>Best Regards!
> >>>
> >>>vrf
> >>>2003-06-17
> >>
> >>
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> >>
> >
> >
> >
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