Audio Fidelity Testing

Updated: June 18, 2008

Windows Vista Logo Program - Audio Fidelity Testing Policy Update

Based on feedback from our OEM partners Microsoft has extended the date to June 1, 2007 for enforcement of the Audio Fidelity tests (SYSFUND-0118 and SYSFUND-0127). This extension will give our OEM partners ample opportunity to prepare for these requirements, while still making systems available with the Windows Vista logo (Premium or Basic) at Windows Vista product launch. System submissions before June 1, 2007 will still be required to contain audio fidelity test log results, however the test logs are not required to pass at this time.

This policy applies to Windows Vista Logo Program system submissions. Test logs for system submissions are generated by using the Windows Driver Test Manager (DTM) running on Windows Vista client SKUs*. The relevant Windows Logo Program v3.0 requirements are SYSFUND-0118 (Premium) and SYSFUND-0127 (Basic).

Timeframe: This policy is effective when the Windows Vista Logo Program opens at Windows Vista RC1 and continues through June 1, 2007.

*Windows Vista Client SKUs include the following versions of the Windows Vista operating system:

• Windows Vista Home Basic

• Windows Vista Home Premium

• Windows Vista Ultimate

• Windows Vista Business

• Windows Vista Enterprise

Summary

The Windows Vista Logo Program (WLP 3.0) for hardware includes two audio fidelity requirements for Windows Vista--a Premium logo requirement (SYSFUND-0118) and a Basic logo requirement (SYSFUND-0127)—that define the minimum bar for audio fidelity quality on a Windows Vista PC. To validate audio fidelity requirements in the Windows Vista timeframe, a new suite of tests has been introduced in the DTM that require a specific piece of testing equipment, the Audio Precision (AP) SYS-2722 audio analyzer.

Note that a subset of fidelity values were defined in the "Designed for Windows XP" logo requirements (WLP 2.x), but were not validated with the Hardware Compatibility Test (HCT) kit.

Based on feedback from our OEM partners, Microsoft is providing alternative methods of submitting test results to validate audio fidelity compliance for system submissions.

Microsoft realizes that this level of audio testing will have an impact on our partners that ship an audio solution in their systems. Improving audio fidelity in the Windows Vista timeframe is extremely important and will benefit our mutual customers. Microsoft encourages you to support this initiative and continue to work through the short-term obstacles to realize the long-term gain.

Options for Submitting DTM Audio Tests

Microsoft has had an open dialog with its industry partners since the introduction of the audio fidelity requirements. It has been agreed that several factors contribute to the difficulty of adopting aggressive logo requirement around audio fidelity at this time: the cost of test equipment, test availability, resources, and the impact that this testing will have on our partners. To temporarily alleviate these burdens, Microsoft will relax the audio fidelity requirements until June 1, 2007, after which submissions with failing audio fidelity test logs will no longer be allowed. Complete and passing audio fidelity test logs must be provided for any submissions after June 1, 2007. This means that the audio fidelity tests are not required to pass at this time, but audio fidelity test logs are required to be included with system submissions for systems that ship with an audio solution.

With the initial release of the DTM at Windows Vista RC1, the audio fidelity tests validate a Line Output jack. To validate line output, Microsoft has developed tests that are to be used with an audio analyzer (see below for information on this device). OEMs are expected to validate specific PC audio implementations by using the DTM and this hardware. Options 1 and 2 are available to OEMs when the Windows Vista Logo Program opens for system submission at Windows Vista RC1. All other applicable audio tests must pass.

Audio fidelity test logs must be provided by using one of the following options:

Option 1 - In-House Testing
OEM partners that complete the system submission test pass by using the audio analyzer hardware without assistance from third parties:

• Purchase the AP machine. Specific machine requirements outlined below.

• Run the audio fidelity tests.

• Submit with audio fidelity test results.

Option 2 - Leveraged Resource Testing
OEM partners that use DTM functionality to import audio fidelity test logs from an outside resource:

• Import the logs from:

  1. The original device manufacturer/motherboard manufacturer

  2. Third-party test house

  3. IHV/codec vendor

  4. Any other test facility that has access to an AP machine and the DTM

• The imported log files must have identical audio 4-part PNPID and pin configuration

• A list of third-party test houses will be provided on this Web page.

A Word from Our Experts about Audio Quality:

Microsoft Windows Vista is designed to support the latest multimedia experiences desired by customers today. Many of these scenarios are greatly enriched by a great audio experience while at the same time are just as severely diminished by the poor audio experience some hardware configurations provide today. Through the "Designed for Windows" Logo Program, Microsoft wants to recognize industry partners who have invested in delivering a quality audio experience. Microsoft plans to expand future audio hardware testing requirements as a way of rewarding industry partners that continue to raise the audio quality bar.

There are five keys advantages to successful audio solutions in the Windows Vista timeframe:

• Discoverability in hardware. Audio input and output devices and ports that can be configurable as logical devices, and exposed and easily identified by the end user in Windows Vista.

• Extensibility in hardware. A standard design that lasts and is the basis for future audio solutions that enable new and exciting scenarios for the end-user.

• Stability from software infrastructure. WaveRT and System Effects Infrastructure.

• Quality from hardware and software. Fidelity, latency, and glitch resilience.

• Connectivity opportunities. New ways to stream and capture audio content.

Audio fidelity affects the entire Windows experience because audio is an integrated part of it. Audio fidelity has migrated away from the levels that were achieved by Consumer Electronic (CE) devices. The decline of audio quality is apparent, and Windows users are taking notice.

Three different metrics are measured today that directly affect the end user:

• DYNAMIC RANGE - Perceived quality

• THD+N - Listener fatigue

• FREQUENCY RESPONSE - Legibility

Current Audio Fidelity Testing

The Fidelity Test will verify that the audio device meets the WLP requirements for a high-fidelity audio playback experience. The test plays a tone that is analyzed by an Audio Precision System Two device that is connected to the analog output jack of the system. The following four test cases appear in the DTM for both Basic and Premium logos.

1. Output Level Test plays a digital full-scale signal and verifies that it meets the Full-Scale Output Voltage requirement in the Windows Logo Program (WLP) Device Fidelity Requirements.

2. Dynamic Range Test takes a noise floor measurement in the presence of signal per AES-17 and verifies that the measurement meets the Dynamic Range requirement in the WLP Device Fidelity requirements.

3. THD+N Test takes a THD+N measurement and verifies the measurement per the WLP Device Fidelity requirements document.

4. Magnitude Response Test measures the frequency response of the device and verifies that it meets the Magnitude Response requirement in the WLP Device Fidelity requirements.

5. Phase Delay Test measures phase differences between channels of multichannel streams on the device, and verifies that these meet the Phase Delay requirements in the WLP Device Fidelity requirements.

Audio Precision Machine Requirements

The Fidelity Test requires an Audio Precision 2700-series machine. This needs to include at least the following modules and filters:

1. Analog generator for capture tests

2. Analog analyzer for render tests

3. AES-17 filter package

4. A-weight filter

In particular, the following are not required for the audio fidelity test: a digital analyzer, a digital generator, or digital signal processor.

The AP models 2702, 2712, 2722 with A-weight and AES-17 filter packages installed meet these requirements.

Importing Test Logs for Audio Fidelity Tests

OEM partners who wish to use the Windows Logo Kit (WLK) to import Audio Fidelity Test logs from an outside resource may want to consider using the following third-party test houses. These test houses are equipped with Audio Precision analyzers for audio and system testing.

Note: This information is provided for informational purposes only and Microsoft makes no warranties, either express or implied, therein. All URLs and other Web-site references are subject to change without notice. The entire risk for the use of this information remains with the user.

A Note on Future Audio Fidelity Testing

The WLP requirements also include audio fidelity numbers for other values that will be tested against in future releases of the DTM. The Fidelity Test will validate both input and output jacks on the system and will be required to pass. The next update of the DTM to validate logo compliance is expected to be released with the next requirement effective date in June 2007.

Future test logs will be required to be submitted from identical systems; this includes identical system device configuration as well. This is the preferred/recommended import scenario.

Where to Go for More Information:

Windows Logo Program Requirements V. 3.0: http://msdn.microsoft.com/en-us/windows/hardware/gg487403.aspx

Setup Verification Details: To ensure that DCOM is working correctly, download DCOMTest.exe from http://support.microsoft.com/kb/259011/ and follow the instructions there.
Task error logs for failed tasks can be sent to the DTMsupp@microsoft.com.

WHDC Audio home page: http://msdn.microsoft.com/en-us/windows/hardware/gg454527.aspx

Additional fidelity test documentation is available as parts of the DTM help documentation.

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