Codecs
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8/28/2008
Codecs convert one audio format type to another.
Typically, conversions are performed between compressed formats and uncompressed formats to reduce the bandwidth requirements of transmitting the audio stream.
By default, Windows Embedded CE includes the following codecs:
- G.711 (both A-law and mu-law encoding)
- GSM 610 (must be included by an OEM in the run-time image)
- G.722.1 (must be included by an OEM in the run-time image)
- SIREN (must be included by an OEM in the run-time image)
Note
The G.722.1 and SIREN codecs are processor-intensive and require hardware support for floating point operations to operate without adding delay. A device that emulates floating point functionality should not use these codecs.
Windows Embedded CE also supports other codecs, such as G.729 or G.723, if they are licensed and installed by the customer.
Windows Embedded CE also supports custom codecs that are wrapped in the ACM interface. For more information about the ACM interface, see Audio Compression Manager Drivers.
Note
Do not place codecs in a region where third parties can delete or modify the codecs. You can mark the DLLs with a system attribute. This prevents untrusted applications from changing the codecs.
The following illustration shows how codecs are handled within the RTC Client API implementation.
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For more information about using an ACM codec with RTC, see RTC Client API Audio Codec Registry Settings.