M4A Validator
Drop any .m4a file to instantly check its structure. Verifies the MPEG-4 container header, walks all top-level boxes (ftyp, moov, mdat), reports codec (AAC or ALAC), sample rate, channels, bit depth, and duration. Also reads embedded iTunes metadata tags. Nothing leaves your browser.
M4A File
Drop a .m4a file here, or
Supports .m4a files up to 200 MB
⛔
Wrong file type — only .m4a files are supported. You dropped a file.
Validation Errors
Warnings
✓ Valid M4A
iTunes Metadata Tags
How It Works
1
Drop your M4A fileDrag it onto the drop zone or click "browse" to select it from your device.
2
MPEG-4 box analysisThe validator checks the
ftyp file-type box, then walks every top-level box — reading moov for technical specs and udta/meta/ilst for iTunes tags.3
Review the reportGet a pass/fail result plus full stats: codec, sample rate, channels, bit depth, duration, ftyp brand, and all iTunes metadata tags.
What Gets Validated
- ftyp box — the first box must declare a compatible M4A brand (
M4A,M4B,mp42,isom, etc.). Any other value or a missing ftyp means this is likely not an M4A file. - moov box — the mandatory movie container box. Contains all structural and metadata information about the audio.
- mdat box — the media data box holding the actual encoded audio samples. A missing mdat may indicate a corrupt or empty file.
- Audio codec — detected from the sample description box (
stsd). Reports AAC (mp4a) or Apple Lossless (alac). - Sample rate & channels — extracted from the audio sample entry in
moov/trak/mdia/minf/stbl/stsd. - Bit depth — reported for ALAC files. AAC files report the sample size from the audio sample entry.
- Duration — calculated from the Movie Header box (
mvhd) using its timescale and duration fields. - iTunes metadata tags — reads the
moov/udta/meta/ilstatom chain for standard tags: title, artist, album, year, genre, track number, and more.
🔒 Privacy & Security
All validation is performed locally using the Web File API and JavaScript ArrayBuffer. Your audio file is never sent to a server. Suitable for private recordings, unreleased masters, or any sensitive audio content.
Related Guides & Tutorials
Guide
The Complete Guide to M4a Validating: Everything You Need to Know
What the validator checks, how to interpret results, and best practices for M4A audio file integrity.
TutorialHow to Use the M4a Validator: Step-by-Step Tutorial
A practical walkthrough of validating M4A files in your browser with real examples.