Audio File Format Specifications

File Description: AIFF, AIFF-C sound file
File Extension: Commonly .aif, sometimes .aiff or .aifc
File Byte Order: Big-endian, although some (little used) formats contain little-endian sound data

Prof. Peter Kabal, MMSP Lab, ECE, McGill University: Last update: 2017-09-20

AIFF / AIFF-C Specifications

The AIFF and the later AIFF-C specifications came from Apple Computer. This format is used on SGI machines. The latest data formats from Apple Computer are supported by the QuickTime player from Apple.

The AIFF and AIFF-C file formats use IFF chunks, each chunk consisting of a chunk identifier, chunk length and chunk data.

Data Types

AIFF files support only PCM data. They can specify any bit depth within a container which has a size which is rounded up to a multiple of 8 bits. Thus they can specify, for instance, 18 bits in a 24-bit container. The data in the container is left justified and zero padded. Data can be read as if it were the full precision of the container. The chunk information and the data (in most cases) is in big-endian byte order.

AIFF-C files can specify a compression type in the COMM chunk. The compression type is NONE for PCM data. The compression type is accompanied by a printable name. The following is a table of common compression types.

Compression Type Compression Name Data Source
NONE not compressed PCM Apple Computer
sowt   PCM (byte swapped) Apple Computer
fl32 32-bit floating point IEEE 32-bit float Apple Computer
fl64 64-bit floating point IEEE 64-bit float Apple Computer
alaw ALaw 2:1 8-bit ITU-T G.711 A-law Apple Computer
ulaw µLaw 2:1 8-bit ITU-T G.711 µ-law Apple Computer
ULAW CCITT G.711 u-law 8-bit ITU-T G.711 µ-law (64 kb/s) SGI
ALAW CCITT G.711 A-law 8-bit ITU-T G.711 A-law (64 kb/s) SGI
FL32 Float 32 IEEE 32-bit float SoundHack & Csound

Differences Between AIFF and AIFF-C Files


Sample AIFF/AIFF-C Files