Guidelines for products that work well with the Microsoft® Windows® xp and Windows Server 2003 operating systems

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B3.0 Audio

B3.1 General Audio

All general requirements in B1.0 are included by reference.
All bus-specific requirements in B2.0 are included by reference.

B3.1.1 General Audio - Windows Compatibility

B3.1.1.1 WDM device driver support for audio

Device driver conforms to the WDM implementation guidelines and “Audio Drivers” reference in the Windows DDK.

Note: This is a general reference, not a requirement.

B3.1.1.2 Windows compatibility and implementation notes (general)

http://www.microsoft.com/hwdev/tech/audio/

Note: This is a general reference, not a requirement.

B3.1.1.3 DELETED

B3.1.1.4 WDM Audio Drivers

http://www.microsoft.com/hwdev/tech/audio/wdmaudio.asp

DirectSound® driver support: see “DirectSound DDK” in the Windows DDK.

Note: This is a general reference, not a requirement.

B3.1.1.5 DELETED

B3.1.2 General Audio - Industry Standards

Note: This list provides complete titles and web locations for references cited. The listing of a reference here does not imply that complete compliance with that reference is a Windows Logo Program requirement.

B3.1.2.1 AC ’97 Component Specification

http://developer.intel.com/ial/scalableplatforms/audio/index.htm

B3.1.2.2 Audio Device Class Power Management Reference Specification, V. 2.0

http://www.microsoft.com/hwdev/resources/specs/pmref/PMaudio.asp

B3.1.2.3 DLS Specification, V. 1.0 or later

http://www.midi.org/

B3.1.2.4 Personal Computer Audio Quality Measurements

http://www.cirrus.com/products/papers/meas/meas.html

B3.1.2.5 USB Device Class Definition for Audio Devices, V. 0.9 or later

http://www.usb.org/developers/docs.html

B3.1.2.6 USB Device Class Definition for MIDI Devices, V. 0.9 or later

http://www.usb.org/developers/docs.html

B3.1.2.7 ACPI Specification

http://www.acpi.info/index.html

B3.1.3 General Audio - Quality

WHQL Test Specification References:
Chapter 16: Audio Test Specification

B3.1.3.1 Pass WHQL tests - See B1.3.

See “Audio” in the HCT documentation.

B3.1.3.2 - See B1.3

B3.1.4 General Audio - Windows Experience

B3.1.4.1 DELETED

B3.1.4.2 Full Duplex

Audio subsystem supports basic data formats

Hardware sample rate conversion (SRC) is not required when the Microsoft software SRC is used. Windows provides software mixing and SRC, which eliminate the need for hardware to support any sampling rate other than 48 kHz.

48 kHz is required because it is the prevalent sampling rate for entertainment content, such as DVD movies. When 48 kHz content is present, the operating system switches the audio output to 48 kHz.

Support for other rates (8 kHz, 11.025 kHz, 16 kHz, 22.05 kHz, 32 kHz, or 44.1 kHz) in hardware is optional.

Audio subsystem supports full duplex operation

Full duplex audio is essential to support emerging communications applications such as Internet Protocol (IP) telephony, conferencing, and network gaming. These applications require the audio system to play back and record simultaneously. The following requirements ensure that full duplex operation is available and performance is consistent across implementations.

Full duplex operation is supported for all sampling rates supported by the hardware.

If the built-in or external audio device includes both input and output capabilities, full duplex operation must be supported for basic formats (16-bit, and 48 kHz), and for all other formats supported by the hardware, for example, at 8 kHz, 11.025 kHz, 16 kHz, 22.05 kHz, 32 kHz, or 44.1 kHz.

Independent selection of input and output sample rates.

If the built-in or external audio device includes both input and output capabilities, the audio device must support independent selection of input and output sample rates.

Sample rates are time-synchronized.

If the built-in or external audio device includes both input and output capabilities, the timing relationship between input and output sample rates must remain constant (i.e., no drift). For example, if 8 kHz is selected for both input and output sampling rate, audio hardware must ensure that the sampling rate for input and output is precisely matched.

Further, when input and output sample rates are set to integer ratios, the actual sample rate ratios must match (i.e., no drift). For example, if 8 kHz input sampling rate and 32 kHz output sampling rate are selected, the ratio of actual sampling rates must be precisely 8:32. This requirement can be accomplished by ensuring that both input and output sampling rates are derived from the same clock, and that sample rate divisors are set correctly.

This requirement helps ensure that Acoustic Echo Cancellation (AEC) and Noise Reduction algorithms maintain performance and convergence.

B3.1.4.3 Plays sounds before and after Suspend/Resume

See A1.1.4

B3.1.4.4 Record and Playback works properly—WHQL Audio test: Audio performance

Mobile PC Note: Exceptions for mobile PCs are defined in the table, “Minimum Performance Requirements.”

B3.1.4.4.1 See B3.1.4.2

B3.1.4.4.2 Digital playback and recording values are increased from 20 Hz to 30 Hz Full-scale input voltage changed from 2.0 to 1.0.

B3.1.4.5 Device Power Management Requirements

Audio devices must comply with Audio Device Class Power Management Reference Specification, Version 1.0, which provides definitions of the OnNow device power states (D0–D3) for these devices. The specification also covers the device functionality expected in each power state and the possible wakeup event definitions for the class. The device and driver are required to implement support for power states D0, D2, and D3. Other power states are optional.

PCI Bus Power Management Interface Specification, Revision 1.1 or later, is the only industry specification that ensures compatibility with the power management capabilities of Windows XP and later.
Minimum Performance Requirements

Requirement	Value
Full-scale input voltage:
FSIV (A-D-PC) line input	1.0 Vrms
FSIV (A-D-PC) microphone input	100 mVrms
Full-scale output voltage:
FSOV (PC-D-A) line output	1.0 Vrms [note 1]
Digital playback (PC-D-A) for line output:
Frequency response (-3 dB) 48.0 kHz source material	20 Hz to 19.2 kHz[note 4]
Dynamic range (DR)	80 dB FS A [note 3, 4]
THD+N (-3 dB FS)	-65 dB FS[note 4]
Digital playback (PC-D-A) for speaker output with 8-ohm load:
Frequency response (-3 dB) 48.0 kHz source material	100 Hz to 19.2 kHz [note 4]
Dynamic range (DR)	80 dB FS A [note 3, 4]
THD+N (-3 dB FS)	-65 dB FS [note 4]
Digital recording (A-D-PC) for line input: [note 2]
Frequency response 48.0 kHz destination	20 Hz to 19.2 kHz[note 4]
Passband ripple	<+/-0.5 dB
Dynamic range (DR)	70 dB FS A [note 4]
THD+N (-3 dB FS)	-60 dB FS (input referenced)[note 4]
Digital recording (A-D-PC) for microphone input:
Frequency response (-3 dB) 22.05 kHz destination	100 Hz to 8.8 kHz
Passband ripple	<+/-0.5 dB
Dynamic range (DR)	70 dB FS A [note 4]
THD+N (-3 dB FS)	-60 dB FS (input referenced) [note 4]
Line output cross-talk:
Channel separation between left and right line-out channels (measured at 10 kHz)	60 dB [note 4]
Sampling frequency accuracy:
Playback	0.1%
Record	0.1%
Notes:
Note 1: For 3.3 V audio codec, the required Full Scale Output Voltage for line output is 0.7 Vrms. Note 2: Line input to speaker output is a requirement only if a line output is not supported. Note 3: Decibels relative to full scale (FS), measured using "A weighting" filters. Note 4 - Mobile PC Notes: The dynamic range requirements are relaxed from previous requirements by 10 dB FS. The THD+N requirements are relaxed by 10 dB FS. The required frequency response is 30 Hz to 15 kHz, measured using 3 dB corners. The cross-talk requirements are relaxed by 10 dB FS.

Current "Designed for Windows XP" Requirements

B3.1.4.5 See B3.1.4.2

B3.1.4.6 Analog microphone input meets jack and circuit specifications

This requirement enables users with electret or dynamic microphones to connect the device to their PC and achieve consistent results. This requirement also maintains compatibility with the installed base of microphones.

If the PC has an analog microphone input, it must meet the following specifications:

Three-conductor 1/8-inch (3.5 millimeters) tip/ring/sleeve microphone jack where the microphone signal is on the tip, bias is on the ring, and the sleeve is grounded.

This design is optimized for electret microphones with three-conductor plugs, but will also support dynamic microphones with two-conductor plugs, where the ring and sleeve are shorted together.

Minimum AC input impedance between tip and ground: minimum, 4 kilohms.
Input voltages of 10–100 millivolts (mV) must deliver full-scale digital input, using software-programmable gain.
Maximum 5.5 V with no load, minimum 2.0 V with 0.8 milliampere (mA) load, direct current bias for electret microphones.
Minimum bias impedance between bias voltage source and ring: 2 kilohms.
AC coupled tip.

B3.1.4.7 Audio driver reports sample position for stream synchronization

The driver must be capable of reporting within 1 ms the current position of the buffer being rendered, in relation to the samples given to the codec. This requirement applies for both compressed and uncompressed data.

Maximum allowable latency is 1 ms.

B3.1.4.8 PCI audio device meets minimum requirements

B3.1.4.8.1 Supports initiator, target, and block transfer.

For complete implementation details, see PCI 2.2. Full-duplex audio sample transport must be supported using separate PCI bus mastering hardware for playback and capture sample streams.

B3.1.4.8.2 PCI device supports efficient audio buffer management.

The audio device must be able to fully function when the system can only provide single pages of contiguous memory. In other words, the audio device can require many pages of memory, but must not require the largest block of contiguous memory to exceed one page.

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.

B3.1.4.8.3 Device does not use ISA-based resources.

B3.1.4.8.4 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:

CD-ROM or DVD
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

Audio subsystem supports AEC reference inputs. Built-in or external audio devices that support full-duplex, stereo playback and record for speakers and microphone must support simultaneous capture of microphone and one or more AEC reference inputs.

At minimum, the audio device must support capture of microphone input in the left channel and a monaural output mix in the right channel, where the monaural output mix is the left and right channels of the main output merged into a single channel. This 1+1 channel interleaved format (similar to stereo) will be referred to as “mic+ref”, and can be easily achieved using existing stereo ADCs.

B3.1.4.12.1 Supports acoustic echo cancellation reference inputs.

See B3.1.4.12

B3.1.4.12.2 Does not rely on analog mixing.

See B3.1.4.8.4

B3.1.4.13 Headset microphone used for speech recognition meets performance requirements

The following requirements are for close-speaking headset microphones intended for use in speech-recognition applications. These requirements are compatible with most of the installed base of sound cards and audio-enabled system boards.

The requirements for a speech-recognition microphone are:

Close-speaking headset design positions microphone within 1.5 inches of the corner of the speaker’s mouth.
FSOV: 100 mV (0 dB FS).
Microphone connector meets requirements.
Operating bias voltage from 2.0–5.0 volts direct current (VDC) with a maximum current drain of 0.8 mA.
Capable of sustaining a maximum voltage of 10 VDC on tip or ring without damage.
Frequency response:
±3 dB from 100 Hz to 10kHz
0 dB at 1 kHz
Minimum sensitivity of –44 dB relative to 1 volt per pascal.
Maximum 2 percent THD+N 100 Hz to 10 kHz at 94 decibel sound pressure level (dBSPL).
Noise cancellation null sensitivity at 90 degrees and 270 degrees, ±10 degrees, with the following minimums:
20 dB at 100 Hz
20 dB at 400 Hz
20 dB at 1000 Hz
20 dB at 4000 Hz
10 dB at 10 kHz
Maximum wind noise sensitivity of –65 dB with 0 dB = 1 V (measured with wind speed of 1 meter per second at the 0 degree axis of microphone).

Maximum output impedance of 1 kilohm (using a 1-kHz full-scale test tone with 2.0 VDC bias).

B3.1.5 General Audio - FAQs

B3.1.5.1 Current related Audio FAQs

See http://www.microsoft.com/winlogo/hardware/.

B3.1.5.2 Updated at A1.1.4.16

B3.1.5.3 See B1.3, B3.1.4.4

B3.1.5.4 See B3.1.4.4

B3.1.5.5 See B3.1.4.6

B3.1.5.6 DELETED

B3.1.5.7 Updated at B3.1.4.5

B3.1.5.8 DELETED

B3.1.5.9 Updated at B3.1.4.2

B3.1.5.10 Updated at B3.1.4.11

B3.1.R General Audio - Future Requirements

Announcement of additional future requirements will be published at http://www.microsoft.com/winlogo/hardware/.

B3.2 Portable Media Devices

B3.2.1 Portable Media Device - Windows Compatibility

B3.2.1.1 Portable media device meets Windows Compatibility requirements

Device must support Windows Media Architecture (WMA) media format
Device can support MP3 or MP3+
Device must use Windows Media Device Manager (WMDM)
Must work with Windows Media Player (WMP)

B3.2.2 Portable Media Device – Industry Standards

B3.2.2.1 Universal Serial Bus Mass Storage Class Specification Overview, Revision 1.0

B3.3.3 Portable Media Device - Quality

B3.3.3.1 Pass all WHQL tests

B3.3.4 Portable Media Device – Windows Experience

B3.3.4.1 Music playback or streaming device provides USB or IEEE 1394 connector

Any music-playback or streaming device that connects to a PC provides USB or IEEE 1394 as a connectivity option, is fully Plug and Play compliant, and supports DRM.

B3.3.4.2 Portable media device uses PC-compatible file system

The portable media device must use a file system that's compatible with Windows — FAT16, FAT32, UDF 1.5 or 2.0, or an installable file system created using the Installable File System (IFS) Kit for the current operating system.

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