.AIFF Audio Interchange File Format
.aiff

Audio Interchange File Format

Convert AIFF audio to MP3, WAV, or OGG directly in your browser — no upload, no server, no quality loss during transfer. FileDex uses FFmpeg WebAssembly to decode Apple's uncompressed audio format and re-encode it locally on your device.

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Audio structure
Header format info
Meta tags · codec
Samples audio data
Uncompressed AudioIFF ContainerLosslessAppleBig-Endian1988
By FileDex

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Common questions

Can I convert AIFF to MP3 without losing quality?

MP3 is a lossy format, so some audio data is discarded during encoding. However, at 192 kbps VBR or higher, the difference is inaudible to most listeners in blind tests. FileDex converts AIFF to MP3 locally in your browser with no file uploads.

What is the difference between AIFF and WAV?

Both store uncompressed PCM audio at identical quality. AIFF uses big-endian byte order in an IFF container (Apple standard), while WAV uses little-endian in a RIFF container (Microsoft standard). WAV has broader cross-platform support; AIFF is preferred in macOS audio workflows.

Why are AIFF files so large?

AIFF stores uncompressed PCM audio — every sample at full precision with no compression. Stereo 16-bit 44.1 kHz AIFF uses approximately 10 MB per minute. Use FLAC for lossless compression at 50-70% of the original size, or MP3 for 10:1 lossy compression.

Is AIFF-C the same as AIFF?

AIFF-C is a compressed variant that adds a codec field to the COMM chunk, supporting IMA ADPCM, MACE, and other compression schemes. Standard AIFF is always uncompressed PCM. Most modern usage refers to uncompressed AIFF.

What makes .AIFF special

Recording studios built on Macintosh hardware standardized around AIFF in the late 1980s, and the format persists in professional audio workflows today. Audio Interchange File Format was developed by Apple in 1988, based on Electronic Arts' IFF (Interchange File Format) chunked structure. AIFF stores uncompressed PCM audio — bit-for-bit identical to the source — making it a lossless archival format.

Continue reading — full technical deep dive

AIFF stores samples in big-endian byte order (Motorola 68000 convention), while WAV uses little-endian (Intel x86). The same 16-bit sample value 0x7FFF is stored as 7F FF in AIFF but FF 7F in WAV. A raw byte-copy between the two formats produces white noise. This endianness difference is the single most common cause of garbled audio when developers hand-roll format converters.

Chunk architecture

AIFF uses the IFF chunk model. Every chunk starts with a 4-byte ID, a 4-byte size field (big-endian), and then the payload. Required chunks:

  • FORM — The outer container. The first four payload bytes spell "AIFF".
  • COMM (Common) — Declares channel count, sample frame count, bit depth, and sample rate. The sample rate is stored as an 80-bit IEEE 754 extended precision float — a quirk inherited from the Macintosh's SANE (Standard Apple Numerics Environment).
  • SSND (Sound Data) — Contains the raw PCM sample data plus an offset and block-size field for alignment.

Optional chunks include MARK (cue markers), INST (instrument parameters for samplers), NAME, AUTH, and ANNO (annotations). Loop points stored in INST and MARK chunks made AIFF the preferred format for hardware samplers like the Akai MPC and E-mu series throughout the 1990s.

AIFF-C: the compressed variant

Apple published AIFF-C (AIFF Compressed) to allow codecs inside the AIFF container. The FORM type changes from "AIFF" to "AIFC", and the COMM chunk gains a compression type field. Common compression types include sowt (little-endian PCM — the name is "twos" backwards), ima4 (IMA ADPCM at 4:1 compression), and NONE (big-endian PCM, identical to standard AIFF). In practice, most "AIFF" files in the wild are either standard AIFF or AIFF-C with NONE compression.

File sizes

Parameters Per minute Per hour
16-bit / 44.1 kHz / stereo (CD) 10.1 MB 605 MB
24-bit / 48 kHz / stereo (broadcast) 16.5 MB 989 MB
24-bit / 96 kHz / stereo (hi-res) 33.0 MB 1.98 GB
32-bit float / 96 kHz / stereo (mixing) 44.0 MB 2.64 GB

These sizes are identical to WAV at the same parameters — the container overhead difference is negligible.

AIFF vs. WAV in practice

Both formats carry uncompressed PCM. The practical differences: AIFF natively supports text metadata in NAME/AUTH/ANNO chunks, while WAV relies on INFO or BWF (Broadcast Wave) extensions that some tools ignore. WAV has a hard 4 GB file limit in its original spec (though RF64/BWF64 extends this). AIFF's 32-bit size fields impose the same 4 GB ceiling.

Logic Pro and GarageBand default to AIFF. Pro Tools defaults to WAV (BWF). Ableton Live and Reaper treat both identically. For cross-platform interchange, WAV is safer because Windows tools occasionally choke on AIFF's big-endian samples. For Mac-centric studios, AIFF remains the native choice.

Limitations

No lossy compression in mainstream use. No streaming support — the entire file must be accessible for playback. No native DRM. No metadata standard as mature as ID3 or Vorbis comments. For distribution, convert AIFF to FLAC (lossless, ~50% size reduction) or AAC/Opus (lossy, ~90% size reduction).

.AIFF compared to alternatives

.AIFF vs .WAV
Cross-platform compatibility
WAV is natively supported on Windows, macOS, Linux, and all browsers. AIFF is primarily an Apple format — Windows and Linux require third-party software for editing, though most players can decode it.
 WAV wins
.AIFF vs .FLAC
File size
FLAC achieves 50-70% compression versus AIFF with zero quality loss. A 40 MB AIFF file typically compresses to 20-28 MB as FLAC. Both decode to identical PCM samples.
 FLAC wins
.AIFF vs .MP3
Audio fidelity
AIFF stores uncompressed PCM — bit-perfect representation of the recorded signal. MP3 discards masked frequencies via psychoacoustic modeling, losing data that cannot be recovered.
 AIFF wins

Technical reference

MIME Type
audio/aiff
Magic Bytes
46 4F 52 4D xx xx xx xx 41 49 46 46 FORM header followed by AIFF signature at bytes 8-11.
Developer
Apple Inc.
Year Introduced
1988
Open Standard
No
00000000464F524DXXXXXXXX41494646 FORM....AIFF

FORM header followed by AIFF signature at bytes 8-11.

Binary Structure

AIFF uses the IFF (Interchange File Format) container. The file begins with a 12-byte master header: 4-byte FORM signature (46 4F 52 4D), 4-byte big-endian file size (excluding the first 8 bytes), and 4-byte format identifier AIFF (41 49 46 46). The body contains chunks, each with a 4-byte ID, 4-byte big-endian size, and payload. The mandatory COMM (Common) chunk stores channel count (2 bytes), sample frame count (4 bytes), sample size in bits (2 bytes), and sample rate as an 80-bit IEEE 754 extended precision float. The SSND (Sound Data) chunk contains the raw PCM samples with an 8-byte sub-header (offset and block size fields). Optional chunks include MARK (cue markers), INST (instrument loop points), NAME, AUTH, and ANNO (annotations). AIFF-C adds a compression type field to the COMM chunk.

OffsetLengthFieldExampleDescription
0x00 4 bytes FORM Signature 46 4F 52 4D (FORM) IFF container identifier. All AIFF files start with these bytes.
0x04 4 bytes File Size varies (big-endian) Total file size minus 8 bytes (excludes FORM signature and this size field). Big-endian byte order.
0x08 4 bytes AIFF Identifier 41 49 46 46 (AIFF) Format type within the IFF container. AIFF for uncompressed, AIFC for AIFF-C compressed variant.
0x0C 4 bytes COMM Chunk ID 43 4F 4D 4D (COMM) Common chunk — contains channel count, sample frames, bit depth, and sample rate.
COMM+8 2 bytes Number of Channels 00 02 (stereo) 1 = mono, 2 = stereo, up to 6 for surround configurations.
COMM+14 10 bytes Sample Rate 40 0E AC 44 00 00 00 00 00 00 80-bit IEEE 754 extended precision float. Example encodes 44100 Hz.
varies 4 bytes SSND Chunk ID 53 53 4E 44 (SSND) Sound Data chunk containing the raw PCM audio samples.
1988Apple introduces AIFF based on Electronic Arts' IFF standard for Amiga, establishing it as the macOS audio standard1991Apple releases AIFF-C (compressed) variant adding codec support including IMA ADPCM and MACE compression1995AIFF becomes the default audio import format for Pro Tools on Macintosh systems2001iTunes launches with native AIFF import/export, reinforcing AIFF as Apple's lossless audio format2004Apple introduces Apple Lossless (ALAC) in iTunes 4.5, beginning AIFF's decline for consumer use2011Apple open-sources ALAC codec; AIFF remains standard for professional DAW interchange on macOS
Convert AIFF to MP3 at high quality ffmpeg 
ffmpeg -i input.aiff -c:a libmp3lame -qscale:a 2 output.mp3

-c:a libmp3lame selects the LAME MP3 encoder. -qscale:a 2 sets VBR quality level 2, targeting approximately 190 kbps — widely considered transparent quality.

Convert AIFF to WAV (lossless re-wrap) ffmpeg 
ffmpeg -i input.aiff -c:a pcm_s16le output.wav

-c:a pcm_s16le writes signed 16-bit little-endian PCM into a RIFF/WAV container. Lossless conversion — only the container and byte order change, not the audio data.

Inspect AIFF file structure and metadata ffprobe 
ffprobe -v error -show_entries stream=codec_name,sample_rate,channels,bits_per_sample -show_entries format=duration,size -of json input.aiff

Displays codec, sample rate, channel count, bit depth, duration, and file size in JSON format. Useful for verifying AIFF vs AIFF-C and checking audio parameters before conversion.

AIFF → MP3 transcode lossy MP3 encoding reduces AIFF file size by approximately 10:1 while maintaining perceptually acceptable quality. Required for music distribution, web audio, and any scenario where uncompressed PCM is impractical due to bandwidth or storage.
AIFF → WAV transcode lossless WAV is the universal uncompressed audio interchange format supported by all DAWs and platforms. Converting AIFF to WAV is a lossless PCM re-wrap from big-endian IFF to little-endian RIFF with no audio data modification.
AIFF → OGG transcode lossy Vorbis in OGG is fully patent-free and achieves good compression for web and open-source applications where licensing restrictions must be avoided.
LOW

Attack Vectors

  • Malformed COMM chunk with extreme channel count or sample rate values can trigger integer overflow in decoders that calculate buffer sizes without overflow checking
  • Oversized annotation (ANNO) or name (NAME) chunks can cause heap buffer overflow in parsers with fixed-size metadata buffers

Mitigation: FileDex processes AIFF files locally using FFmpeg WASM in a sandboxed browser environment. No data is sent to external servers.

Logic Pro tool
Apple's professional DAW with native AIFF recording, editing, and export
Audacity tool
Free, open-source audio editor with native AIFF import/export support
FFmpeg tool
Universal media framework with AIFF demuxing and PCM decoding
libsndfile library
C library for reading and writing AIFF, WAV, FLAC, and other audio formats
Core Audio (macOS/iOS) library
Apple's native audio framework with first-class AIFF support