Convert MP4 to M4A
Free online converter for MP4 files. AAC audio in an MP4 container. Nothing to install, no watermark, and every file is deleted automatically.
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Upload a MP4 file to convert it to M4A. Up to 3 files at once, 100 MB each.
Free · up to 3 files · 100 MB each · files deleted automatically after 1 hour.
About MP4 and M4A
MP4 .mp4
The universal video container, normally holding H.264 video and AAC audio. If a device plays video at all, it plays MP4.
Good for
- Plays on effectively every device, browser and editor
- Excellent compression at high quality
- Streams well, and seeks quickly
Trade-offs
- H.264 carries patent licensing obligations
- Lossy — quality drops each time it is re-encoded
- Less flexible than MKV for subtitles and multiple tracks
video/mp4
M4A .m4a
An MPEG-4 container holding audio only — usually AAC, sometimes lossless ALAC. The extension tells you the wrapper, not the contents.
Good for
- Rich tagging, including chapters and artwork
- Holds either lossy AAC or lossless ALAC
- The standard for iTunes and Apple Music files
Trade-offs
- The extension alone does not tell you the quality inside
- Support outside Apple platforms is inconsistent
audio/mp4
MP4 and M4A side by side
| MP4 | M4A | |
|---|---|---|
| Compression | Lossy (usually H.264) | Container — usually lossy AAC |
| Transparency | No | n/a |
| Typically used for | Everything — the safe default for video | Apple audio, audiobooks, podcasts |
What changes when you convert MP4 to M4A
Only the sound is kept
This takes the audio track out of the MP4 and writes it as M4A. The picture is discarded entirely, and no conversion back will return it — keep the MP4 if you still need the video.
This is a re-encode, not a repackage
Some tools can move a stream into a different container untouched when the codecs happen to line up. We do not — every job here is decoded and encoded again, so the conversion takes time in proportion to the length of the file and costs a small amount of quality even where a repackage would have been possible. In exchange the output is predictable: it plays everywhere, rather than inheriting whatever the source happened to contain.
What your M4A will contain
The output is AAC — the same codec a bare .aac file holds, wrapped in an MP4 container so that artwork and tags have somewhere to live.
Other MP4 conversions
Other ways to get M4A
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