Codec Central - IMA Audio Codec



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IMA

22kHz mono 11KBps
"Modern World," copyright Gary Lamb

General Information

Overview
IMA is a cross-platform audio codec which offers 4:1 compression, and is built into QuickTime 2.1 and later. It only works on 16-bit audio, and provides very good sound quality.

Architectures Supported

Pros, Cons & Tips

Pros

4:1 compression allows a 16-bit, 22 kHz audio soundtrack to fit into half the space of a 8-bit, 22 kHz soundtrack -- but sounds better.

Cons

Since IMA is only 4:1 compression, it is not great for Web video.
Strong low-frequency sounds, such as drumbeats, may not be accurately reproduced.

Tips

Mark Cookson's guide to "Understanding the Differences Between Apple and Windows IMA-ADPCM Compressed Sound Files"

Ideal source material	Most audio
Compression Ratio / Datarates	4:1 compression of 16-bit samples
Compression time	-
Special features	-
Encoder requirements	Any MacOS or Windows
Decoder requirements	Any MacOS or Windows
Encoder availability	Built into QT 2.1 and later
Decoder availability	Built into QT 2.1 and later
Manufacturer	Apple

If you have any comments or tips & tricks to share about IMA, please contact us at info@terran-int.com.