Fei_1840877
December 30th, 2004, 03:33 PM
Dear Sir,
Problem Description – Unable to capture audio from USB Audio Device when the format is set to MuLaw.
Scenario – We developed USB Audio Device that produces Audio in MuLaw Format. The USB descriptors are correctly set to indicate that the Audio format. Please see the attached file showing the descriptors.
Description – We want to capture Audio in MuLaw format. Windows DDK documentation states that it supports all “All Type I formats” (MuLaw being one of them). Refer to http://www.microsoft.com/whdc/device/audio/usbaud.mspx (document name - USB_Audio_and_Windows.doc). Also refer to the same information in Windows DDK documentation at mk:@MSITStore:C:\WINDDK\2600\help\stream.chm::/hh/ddkslm/stream/aud-design_8gmr.htm.
When we connect the Audio device Windows recognizes it properly as an Audio device and shows it in the Control Panel. When we check the Audio formats using both GraphEdit (DirectX 9.0) and Adobe Audition, it shows as “None”. As a result we are unable to capture Audio from the device.
Additional Info – When we change the USB Audio Device properties (by changing the descriptors) to PCM8 the device works without any problem.
Problem Description – Unable to capture audio from USB Audio Device when the format is set to MuLaw.
Scenario – We developed USB Audio Device that produces Audio in MuLaw Format. The USB descriptors are correctly set to indicate that the Audio format. Please see the attached file showing the descriptors.
Description – We want to capture Audio in MuLaw format. Windows DDK documentation states that it supports all “All Type I formats” (MuLaw being one of them). Refer to http://www.microsoft.com/whdc/device/audio/usbaud.mspx (document name - USB_Audio_and_Windows.doc). Also refer to the same information in Windows DDK documentation at mk:@MSITStore:C:\WINDDK\2600\help\stream.chm::/hh/ddkslm/stream/aud-design_8gmr.htm.
When we connect the Audio device Windows recognizes it properly as an Audio device and shows it in the Control Panel. When we check the Audio formats using both GraphEdit (DirectX 9.0) and Adobe Audition, it shows as “None”. As a result we are unable to capture Audio from the device.
Additional Info – When we change the USB Audio Device properties (by changing the descriptors) to PCM8 the device works without any problem.