The audio codecs themselves appear in the Type menu in the Audio Settings panel of either dialog box. Some of the codecs below use a specific compression ratio (such as 2:1). When they do, the compression ratio is listed after the codec name. In general, use a codec specifically designed for the type of audio in your program, such as speech, music, or multimedia. Avoid codecs intended for telephony unless your audio is almost exclusively speech to be delivered over low-bit-rate media such as the Web.
Useful for exchanging audio with applications on platforms (such as many UNIX workstations) where µ-Law is a standard audio format. µ-Law is used for digital telephony in North America and Japan. (The first letter of the codec name is a Greek letter pronounced Mu.)
16-bit Big Endian and 16-bit Little Endian
Useful when audio must be stored using Big Endian or Little Endian (byte order) encoding, such as when preparing microprocessor-specific audio. These codecs are useful for hardware and software engineers but are generally not useful for video editing.
24-bit Integer and 32-bit Integer
Useful when the audio data must be stored using 24-bit or 32-bit Integer encoding, such as when preparing microprocessor-specific audio. These codecs are useful for hardware and software engineers but are generally not useful for video editing.
Useful for cross-platform audio for multimedia. IMA 4:1 was developed by the IMA using ADPCM.
32-bit Floating Point and 64-bit Floating Point
Useful when audio must be stored using 32-bit or 64-bit floating point encoding, such as when preparing microprocessor-specific audio. These codecs are useful for hardware and software engineers but are generally not useful for video editing.
Similar to µ-Law, but used primarily for digital telephony in Europe.
MetaSound/MetaVoice Codecs (Mac OS only)
A wide series of codecs developed by Voxware. These codecs discard parts of the audio signal that are imperceptible to the human ear so the compression provides high music quality with high compression. The codecs cover a wide range of bit rates from AC06 V2.0 at 6,000 bps to the ACS96 V2.0 at 96,000 bps in order to accommodate varying bandwidths.
Intended for speech; works best at 8 kHz. Based on the Code Division Multiple Access (CDMA) technology standard for cellular telephony.
QDesign Music Codec
Useful when compressing high-quality music for Internet distribution. It is capable of delivering CD-quality (16-bit, 44.1 kHz) audio over a 28.8 Kbps line.
MACE 3:1 and MACE 6:1
Useful as a general-purpose audio codec. The Macintosh Audio Compression and Expansion codec (MACE) has been built into the Mac OS Sound Manager for many years. MACE 3:1's lower compression ratio provides higher quality than MACE 6:1. Because it is provided with QuickTime 3.0 and later, it is also accessible in Windows when QuickTime is installed.