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Audio Hardware Considerations (Windows Embedded CE 6.0)

  • Article

1/5/2010

For information about developing device drivers for a specific type of device, see Windows Embedded CE Drivers.

Sample Rates

You must support a sample rate of 44.1 kilohertz (kHz). Supporting other sample rates is not required because the audio manager upconverts or downconverts other sample rates to 44.1 kHz. When the audio manager upconverts or downconverts audio, it consumes microprocessor cycles; so it is advantageous to support as many sample rates as possible. Supporting the following sample rates is part of the certification requirement for PlaysForSure certification, but supporting these sample rates does not guarantee PlaysForSure certification:

  • 32.0 kHz
  • 44.1 kHz
  • 48.0 kHz
  • 64.0 kHz
  • 88.2 KHz
  • 96.0 kHz

For more information about the PlaysForSure logo requirements, see this Microsoft Web site and this Microsoft Web site.

Bits per Audio Sample

  • Required: 16 bits per audio sample
  • Optional: 24 bits per audio sample

Surround-Sound Audio

To provide a cinema-like audio experience, Microsoft recommends that you support Dolby Digital and DTS surround-sound audio. If you implement surround-sound audio, your device must mix down the multichannel surround-sound audio to stereo and then send the output through the RCA stereo connectors.

Hardware Audio Decoder

A hardware audio decoder handles audio decoding, which allows the microprocessor to handle other tasks and process other data. Offloading audio decoding to a hardware audio decoder facilitates a smoother and more robust audio playback experience.

To offload audio decoding to a hardware audio decoder, you must implement a DirectShow DirectX Media Object (DMO) filter driver for the hardware audio decoder. The networked media device (NMD) software provides a DirectShow DMO filter driver, but if your hardware platform has a different hardware audio decoder, you must obtain the DirectShow DMO filter driver from the manufacturer of the hardware audio decoder or from a third party.

Microsoft recommends providing a hardware audio decoder for the following audio formats:

  • Dolby Digital/AC3 5.1, 6.1, 7.1
  • DTS 5.1
  • MP3
  • MPEG-2 Advanced Audio Coding (AAC)
  • MPEG-4 AAC
  • WMA 9
  • WMA 9 Lossless
  • WMA 9 Professional
  • WMA 9 Voice

Audio Connections

Your NMD must have at least one RCA stereo audio connector. This RCA stereo audio connector allows the audio output to connect to a TV or to a stereo system.

An S/PDIF audio input/output (I/O) connector is recommended. The S/PDIF audio I/O connector allows the digital audio output to be directly sent to a surround-sound receiver.

A headphone stereo audio connector is optional. For private listening, a user can use the headphone stereo audio connector to connect a stereo headphone to a television or to a stereo system.

See Also

Concepts

Hardware Architecture Diagram for Networked Media Devices

Other Resources

Performance Considerations for the Hardware Components of Networked Media Devices
Core OS Services
Developing a Board Support Package
Developing a Device Driver
Developing an OEM Adaptation Layer
CETK Tests