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Microsoft Windows Logo Program System and Device Requirements  —  84

This requirement ensures audio support in docking and dynamic loading scenarios where memory may be fragmented with respect to pages.

The audio device and associated device-specific driver must not introduce unnecessary latency. If the audio driver adds more than 2 milliseconds of computational latency between buffer transfer and queuing for rendering, the driver must provide a programmatic method for a latency sensitive application to temporarily disable the computation.

This requirement helps to ensure that telephony applications closely resemble the performance of a conventional phone and minimizes the possibility that audio and video streams will appear out of synch.

B3. Device does not use ISA-based resources.
B3. Audio subsystem is digital ready.

Audio sources must be available as digital audio streams accessible to the system-wide kernel, that is, they must not rely exclusively on any analog mixing stage between the digital-to-analog converter and the speaker jack as the only means for output. Sources that continue to offer an analog mixing output configuration must also provide the user a configurable digital option.

One model for providing the user such an option is Windows support for CD Music.

The audio sources covered by this requirement, which must be available digitally to USB speakers if attached, are:


TV tuner

FM radio

Voice modem

Analog Mic and Line In with available analog-to-digital converters (ADCs) are digital ready by definition. Devices for which the operating system supports emulation equivalents, such as hardware accelerated 3-D and MIDI synthesis (Microsoft DirectSound® 3D emulation and the Windows GS Wavetable SW Synth) are excepted.

This requirement assures that all audio content can be made available at both the analog jack and USB port. Elimination of the dependency on analog mixing for output is key to making PC audio easier to configure and use, and it removes a major obstacle for USB audio rendering devices.

B3.1.4.9 USB audio device uses HID controls

USB audio devices must use an HID to control basic functions. If a USB audio device plans to implement volume adjustment controls, it must employ the HID usages provided on the consumer controls page in the USB HID Usage Tables, Version 1.1 specification and in “Windows Support for HID-based Audio Controls.”

B3.1.4.10 Support required for DirectX functions as specified in the DirectX SDK “DirectX Audio” and the Windows DDK “Audio Drivers” section
B3.1.4.11 Device implements DRM support as defined in Windows DDK

To pass Windows Logo testing for Secure Audio Path for Digital Rights Management as DRM compliant with DRM Level = 1200 (which is the security level for Windows XP), audio drivers must not call DrmForwardContentToFileObject.

"Digital Rights Management Reference” in the Windows DDK.

B3.1.4.12 Audio subsystem requirements

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