[wdmaudiodev] Vista trouble

  • From: Stephan Kappertz <stephan@xxxxxxxxxx>
  • To: "wdmaudiodev@xxxxxxxxxxxxx" <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Mon, 18 Dec 2006 17:08:36 +0100

Hi All,

I'm running into several problems (trying to) making our audio drivers Vista RTM compatible:

* The Vista Sound Control panel is the only place where the sample rate can be selected. This causes several unwanted side effects for us:

1) Unfortunately Vista doesn't seem to have a mechanism to update the currently selected sample rate if it is not available any more (due to a change in the external sync for example). As a result, trying to record in an audio application fails even if the sample rate selected in the application is the new external rate. Vista tries to open the driver with the preselected sample rate, fails and doesn't run the IntersectHandler again.

2) In our multichannel device drivers, we're exposing several virtual (stereo) devices that are all running from the same sample clock. Exposing the virtual devices and not just one multichannel device is necessary because users can't select the stream position of a stereo signal in the interleaved multichannel stream in their application. They wouldn't be able to send a stereo audio stream out to channel 7&8 for example.

Now since the Vista Sound Control panel opens all available audio input to show the input VU meters, the sample rate is fixed at the initial value. Any attempt to change the input sample rate for one of the virtual devices fails because others are open and streaming. As a result Vista displays a message box saying "this sample rate is not supported
by the device" even though the rate is supported by the hardware.

3) For the inputs, the Vista Sound Control panel (audio subsystem) doesn't seem to support more than stereo devices. All selectable formats are stereo, even though our device has 8 input channels defined in its DataRanges. If I'm rejecting stereo formats in the IntersectHandler and just allow 8 channel interleaved formats, the Sound Control panel format selector is completely disabled. As a result, audio apps can't record 8 channel interleaved either.

* AC3/WMA Pro over SPDIF works only if the pin category is KSNODETYPE_SPDIF_INTERFACE. Unfortunately we have several devices that don't expose a separate SPDIF stream engine. Instead, the SPDIF out mirrors the analog out and analog gets muted if an AC3/WMA Pro is played. There's no way to enable AC3 support on these devices other than defining the main output pin as KSNODETYPE_SPDIF_INTERFACE. But this causes the wrong icon to be displayed in the Sound Control panel. Moreover the speaker setup (stereo, quad 5.1) isn't available any more if we change the category.



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