Optimal Sound News - Microsoft Releases Guide to Array Microphone Implementation

Microsoft Releases Updated Guide to Array Microphone Implementation

A major update to a white paper from Microsoft provides previously-unavailable details on how the Acoustic Echo Cancellation and Microphone-Array Beamforming processing built into Windows Vista is implemented, as well as how to test it and use it. Click here to download the updated white paper from the Microsoft web site.

Step-by-step instructions are provided on how to structure firmware for USB-based microphone array devices, along along with details on the Microphone Array Geometry Descriptor Format and Audio Packet Overview. The document goes on to describe how an application discovers a microphone array and how to retrieve the microphone array geometry.

Voice Capture DMO Structure and Interfaces are documented, along with step-by-step instructions on how an application can initialize the Voice Capture DMO, set the DMO Output Format, and process DMO inputs and outputs.

Examples are provided for USB Microphone Array Descriptors, Device and Configuration Descriptors, Microphone Terminal and Unit Descriptors, and Audio Streaming Interface Descriptors.

The Microphone Array Coordinate System is also documented.

This is followed by actual source code examples which are similar but not identical to the source code in the AECMicArray demo that is part of the Windows SDK. There is also some new source code for a sample unit test which discovers devices and retrieves array geometry. This code contains some of the functionality included with Microsoft's new Microphone Array Verification Tool.

Click here to download the updated white paper from the Microsoft web site.

For additional software details, see the voice capture DMO sample code, which is installed with the Windows Software Development Kit (SDK) under the %MSSDK%\Samples\Multimedia\Audio\AECMicArray\ folder.

Finally, the KSAUDIO_MIC_ARRAY_GEOMETRY and KSAUDIO_MICROPHONE_COORDINATES structures are documented. Any audio driver supporting beamforming microphone arrays must include these properties in order to use the AEC DMO in source mode. Alternately, an application can provide the geometry directly if it uses the DMO in filter mode, though this requires quite a bit more plumbing in order to get the same result.

Click here to see Optimal Sound's previous coverage of the High Quality Voice Capture DirectX Media Object (DMO).

Additional links are provided to white papers from Microsoft researcher Dr. Ivan Tashev:
A New Beamformer Design Algorithm for Microphone Arrays, March 2005
Self-Calibration Procedure for Microphone Arrays, July 2004 .

For Microsoft documentation on DirectX Media Objects, click here .

Use Optimal Sound services to add an audio expert to your team, and ensure that your systems sound great, are easy to understand, and function properly with Windows Vista. Contact us for more info.

News about HD Audio and Windows* Vista*

Microsoft Releases Updated Guide to Array Microphone Implementation A major update to this white paper from Microsoft provides previously-unavailable details on how the Acoustic Echo Cancellation and Microphone-Array Beamforming processing built into Windows Vista is implemented, as well as how to test it and use it. For more info, click here.

Microsoft Releases New Microphone Array Verification Tool Microsoft has released a command-line tool which can verify whether an audio driver accurately reports microphone-array geometry information and whether the Voice Capture DMO operating in microphone-array mode processes the captured data accurately. For more info, click here.

Microsoft includes built-in Acoustic Echo Cancellation and Microphone Array Processing in Vista As part of DirectShow 9, Microsoft has included Vista-only source code with the new Windows SDK. This source code can be compiled to create a test app which demonstrates the Acoustic Echo Cancellation DMO. While initially intended for use with USB-based array microphones, guidelines are provided for HD Audio implementation as well. For more info, click here.

Microsoft Documents Limit on DTM Test Storage, outlines possible solutions Driver Test Manager (DTM) is the new logo testing infrastructure used for both Windows Vista and Windows XP logo submissions. The default installation is limited to 2 GB of storage, which is enough to get started, but probably not enough for serious DTM users. To find out more options, click here.

Microsoft includes Audio System Effects in Vista Microsoft has released an updated white paper on how to use the Audio System Effects that are included at no charge in Windows Vista. In-box built-in effects include
    Loudness Equalization DSP (LFX)
    Forward Bass Management (LFX)
    Reverse Bass Management (LFX)
    Low Frequency Protection (LFX)
    Speaker Fill (LFX)
    Room Correction (GFX)
    Virtual Surround (LFX)
    Speaker Phantoming (LFX)
    Virtualized Surround Sound over Headphones (LFX)
    Bass Boost (LFX)
For more details, click here.

Microsoft WHQL postpones date that systems must pass audio fidelity tests On Thursday, August 30, Microsoft's Hardware newsletter announced that systems will not be required to pass the audio fidelity portion of the logo tests until June 1st, 2007. However, all submissions must include complete logs from the audio fidelity tests, which requires an Audio Precision System 2 test set to be connected to the DTM test environment. For more info, click here.

Audio Fidelity Testing Now Required for Vista Audio Device Logo Microsoft has released Windows Logo Program (WLP) specification 3.07, which has significant impact on the audio development and logo submission process for Windows Vista. Audio devices and drivers are now required to included passing audio fidelity test logs in order to qualify for device logo. For more info, click here.

Windows Vista RC2 to be released October 6, 2006 Recently disclosed details of Windows Vista RC2 release indicate that Vista build 5743 will be released Friday, October 56, 2006, and will be designated as Vista Release Candidate 2 (RC2). For more info, click here.

Audio Design Line Publishes excerpt from HD Audio Book EE Times affiliate Audio Design Line, has reprinted Chapter 9 of the new book from Intel Press, High Definition Audio for the Digital Home: Proven Techniques for Getting It Right the First Time by David Roach, Scott Janus, and Wayne Jones. This chapter of the book describes the complete signal audio signal path of a modern PC, including both hardware and software audio components. For more info, click here.

Microsoft publishes sample code for 3 different Audio System Effects Microsoft has released sample code for three different sample Audio System Effects along with a retitled document describing how to use them. For more info, click here.

Microsoft Multimedia VP Amir Majidimehr writes about Audio System Effects included in Windows Vista Read first-hand the thinking behind the new Audio System Effects included in Windows Vista. For more info, click here.

Microsoft Channel 9 Video on audio hardware for Windows Vista features Hakon Strande and David Roach Check out the 38-minute Channel 9 video featuring Hakon Strande of Microsoft and David Roach of Optimal Sound discussing the audio hardware in Vista. For more info, click here.

Microsoft Releases HD Audio Pin Configuration Test Guidelines Microsoft has released a paper entitled Microsoft HD Audio Pin Configuration Implementation Test Procedure Guidelines. The paper describes how to use a Microsoft-supplied pin configuration utility to generate and validate a set of verb tables which is embedded in the system BIOS. The verb table describes the audio configuration of the system. If the verb table is configured incorrectly, the UAA HD Audio class driver will not function properly and the Windows Vista logo tests will fail. For more info, click here.

News about HD Audio & Vista

Microsoft Releases Updated Guide to Array Microphone Implementation

News about HD Audio and Windows* Vista*