Appendix B
Microsoft Audio Compression Manager
The Microsoft Audio Compression Manager (ACM) is a standard interface for audio compression in Windows. This interface allows applications such as Sound Forge® Pro to use compression algorithms provided by other companies.
Sound Forge software fully supports audio compression through the ACM. This allows you to use any
There are two major components to the ACM:
•Audio data compression and decompression
•Transparent playback and recording of
Audio data compression and decompression
The first component of the ACM allows audio data to be compressed and decompressed. Audio compression is used to decrease the amount of data required to represent a sound and results in smaller sound files. However, there are drawbacks to using audio compression on sound files:
•Most audio compression algorithms degrade sound quality. This is referred to as lossy compression because information contained in the sound is lost when it is compressed. The amount of sound degradation is dependent upon the algorithm.
•Compressed audio requires more processing time than uncompressed data. The amount of processing time is dependent on the algorithm as well as the system’s hardware. Typically, opening and saving compressed files takes longer than uncompressed files.
•Compressed files are not as portable as uncompressed files. To distribute WAV files in a compressed format, you must verify that the audience can use them. Also, not all audio software can use compressed WAV files, which may make using other applications with the Sound Forge software difficult.
In Sound Forge software, any compressed WAV file can be opened if a compatible ACM driver is installed. If no compatible ACM driver is available for a compressed WAV file, you are alerted to the problem.
Saving compressed WAV files is as simple as specifying the compression algorithm in the Format
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