Windows Vista -
Windows Media Player Audio Playback and Audio Stack
Published on 12/9/2006
To improve reliability and to simplify audio application development in Windows Vista, the Windows audio stack has been redesigned.

Windows Media Player Audio Playback and Audio Stack

Microsoft Windows Media Player 11 uses a new multimedia API in Windows Vista that is called Media Foundation. Media Foundation provides Windows Media Audio (WMA), Windows Media Video (WMV), and MP3 media formats. Because of these changes, Windows Media Player audio playback may behave differently in Windows Vista than Windows Media Player audio playback behaves in Microsoft Windows XP. This article discusses aspects of audio playback in Windows Vista and provides options to modify symptoms that you may experience therein.

Description of the Windows Vista audio stack
This section describes the Windows Vista audio stack and some of the Windows Vista audio stack components. Applications that provide audio write uncompressed audio data to a buffer in a new Windows component that is called the Audio Engine.

To view the settings for these effects, click the Enhancements tab, and then click the Speakers Properties dialog box.

Volume control and Windows media player effects do not work in the Audio Engine exclusive mode
This can be controlled in the Advanced tab of the Speaker Properties dialog box. In exclusive mode, the whole Audio Engine stack is bypassed. Therefore, system sounds, per-session volume controls, and Windows Media Player enhancements do not work.

Mono content in multichannel hardware is provided through center speaker only
If this default behavior presents hardware difficulties, use the Speaker Setup dialog box that is available in Control Panel to change the number of audio channels that run to the stereo. This causes the Audio Engine to send mono audio to the left and right channels.

Brief silence around 200 milliseconds (ms) when you play encoded audio over S/PDIF
If this behavior is a problem, the user can disable encoded audio output by disabling the encoded formats in the Supported Formats tab of SPDIF Interface Properties dialog box of the S/PDIF audio device.

Cross fading from stereo to multichannel audio does not work if Speaker Fill is enabled
Cross fading is a feature in Windows Media Player that lets the next song softly start before the current song ends.