QuickTime 4 Reference

Support for Sound Data Compression

The sound sequence grabber channel now supports compressing sound data in software when the requested format is not supported directly by the sound input driver. This feature is available only when Sound Manager 3.1 or later is installed. You can now directly capture sound in IMA and Law formats. Because new audio compressors and decompressor can be installed by system extensions, other audio compression formats may also be available.