M4A — AAC (MP4)
The clip as AAC in an MP4/M4A container (faststart) — Apple's default audio container. For testing M4A parsing and MP4 audio conversion.
Specifications
- Source
- 3 s A-major triad, 44.1 kHz stereo
- Codec
- AAC-LC
- Container
- MP4
- Lossless
- false
What is a .m4a file?
M4A is an MPEG-4 audio container, essentially an MP4 file holding audio-only content, usually AAC or sometimes Apple Lossless (ALAC). It supports rich metadata and chapters and is the standard for iTunes and Apple Music downloads. The .m4a extension signals audio-only MP4 content.
How to use this file
Use an example M4A to test MP4 container parsing, AAC or ALAC decoding, metadata and chapter extraction, and converters between M4A and MP3 or FLAC.
How to use this file for testing
“M4A — AAC (MP4)” is a deterministic Novus Examples fixture for Conversion testing, Audio analysis. The same content exported across many formats and linked as a group, so you can convert one and diff against the expected twin.
Documented properties for this file: M4A · 74,067 bytes. Compare results against paired or grouped companions on this page when present (clean↔damaged, searchable↔scanned, or format twins) so scores stay reproducible across runs.
Download the file once, keep the path stable in CI or local scripts, and treat the spec table as the contract: dimensions, seeds, field lists, and roles are intentional. Corrupt or invalid samples are labelled as such — expect parsers to fail loudly rather than silently accept them.
Media fixtures are short and synthetic by design. Prefer waveform or transcript ground truth in the same group when measuring ASR, trim, upscale, or sync tools; do not assume broadcast-quality masters.
Code examples
<audio controls preload="none" src="triad.m4a"></audio>Related files
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- wav1 kHz Tone @ 44100 Hz Sample Rate (WAV)A 1 kHz sine tone sampled at 44100 Hz — part of a sample-rate ladder (8/16/44.1/48/96 kHz) of the identical tone, for testing resampling, sample-rate detection, and aliasing.
- wav1 kHz Tone @ 48000 Hz Sample Rate (WAV)A 1 kHz sine tone sampled at 48000 Hz — part of a sample-rate ladder (8/16/44.1/48/96 kHz) of the identical tone, for testing resampling, sample-rate detection, and aliasing.
- wav1 kHz Tone @ 8000 Hz Sample Rate (WAV)A 1 kHz sine tone sampled at 8000 Hz — part of a sample-rate ladder (8/16/44.1/48/96 kHz) of the identical tone, for testing resampling, sample-rate detection, and aliasing.
- wav1 kHz Tone @ 96000 Hz Sample Rate (WAV)A 1 kHz sine tone sampled at 96000 Hz — part of a sample-rate ladder (8/16/44.1/48/96 kHz) of the identical tone, for testing resampling, sample-rate detection, and aliasing.
- wav440 Hz Tone @ 16-bit (WAV)A 440 Hz sine tone stored as 16-bit PCM — part of a bit-depth ladder (8/16/24-bit) of the identical tone, for testing bit-depth conversion, dithering, and quantisation-noise handling.
Generated by generation/audio_codecs.py. Free for any use, no attribution required — license.