audio/x-aiff

Apple's 1988 answer to the uncompressed-audio question, built on Electronic Arts' IFF 85 chunk container from the Amiga — which makes AIFF the big-endian sibling of the little-endian WAV that Microsoft assembled from the same ideas three years later. Pro audio on the Mac lived on .aiff for decades, and one eccentric detail endures: the sample rate is stored as an 80-bit IEEE 754 extended float, a type virtually nothing else on disk uses. The format was never registered, so the x- name is the real name. Files open with FORM at offset 0 and declare AIFF — or AIFC for the compressed variant — at offset 8.

.aiff and .aif are the same thing; .aifc marks the AIFF-C variant that permits compressed codecs.

Defined by Library of Congress format description — AIFF. Registry facts from the IANA media-types registry via mime-db.