Turn MP4 files into AIFF
Pull the sound out of your MP4 and keep it as an AIFF, leaving the picture behind. MP4 is the video file that plays everywhere: phones, TVs, browsers, editors and every social platform. Worth knowing: an AIFF will not open in a browser tab, so it is a file for software rather than for the web. Your file never leaves your computer.
How to convert MP4 to AIFF
- 1 Drop your MP4 .mp4 file onto the page, or click to browse for it.
- 2 Choose the sound quality, or lift the existing track out untouched where that is possible.
- 3 Convert. The work happens on your own machine, so how long it takes depends on your computer and the file.
- 4 Download the AIFF, or add more files and do the whole set in one go.
Why convert MP4 to AIFF
- You only want the sound: a lecture, an interview, a podcast that was filmed, or a track to listen to with the screen off.
- You want a copy that will not get any worse each time you edit and save it, and AIFF gives you that.
- Exactly as recorded, identical in quality to a WAV.
- Holds track details better than a plain WAV.
- Professional recording and mastering on macOS.
MP4 compared with AIFF
How the two formats differ on the things that decide whether a conversion is worth making.
| Property | MP4 | AIFF |
|---|---|---|
| File extension | .mp4 | .aiff |
| Compression | Lossy | Uncompressed |
| Typical file size | Smaller | Largest |
| Browser support | Every browser | Some browsers |
| Introduced | 2001 | 1988 |
| Developed by | ISO/IEC MPEG | Apple |
Quality and what changes
Whether anything is lost depends on the codec. If the track already matches the target, it can be copied out untouched and the audio is bit for bit what was in the MP4. Choosing a different codec means decoding and re-encoding, which is a second generation of lossy compression on top of whatever the video already applied. Encoding at 192 kbps or above keeps that second generation inaudible for most material.
- Browsers will not display an AIFF, so it downloads rather than opening in a tab.
- One AIFF limitation to keep in mind: less universally supported on Windows and web.
Questions about MP4 to AIFF
Does converting MP4 to AIFF improve the quality?
No. AIFF preserves what it is given perfectly, including the compression artefacts already present in the MP4. It stops further loss from happening, which is worth doing before editing, but it cannot recover detail that was discarded.
Why is my AIFF bigger than the MP4?
Because MP4 was discarding data and AIFF is not. A lossless format has to write out every pixel it is handed, artefacts included, so growing several times over is normal and does not mean anything went wrong.
Does extracting the audio re-encode it?
Only when the target codec differs from the one in the MP4. Where they match, the track is copied and the result is identical to the audio inside the video. Converting to a different codec means one extra generation of lossy compression.
Is my MP4 file uploaded anywhere?
No. The whole thing runs inside the browser tab you already have open. Your MP4 is read straight from your own disk, converted on your machine and handed back as an AIFF. Nothing is sent anywhere, nothing is stored and there is no account.
Is there a file size limit?
There is no server-side limit because no server sees the file. The real ceiling is your device memory, since the input and the output both have to fit in the tab. A few hundred megabytes is usually fine on a desktop machine and considerably less on a phone.
Can I convert several MP4 files at once?
Yes. Add as many as you like and they are processed one after another, then offered as separate AIFF downloads or as a single ZIP. Speed depends on your own processor rather than on a queue.
Does the converter work offline?
Yes, after the page has loaded once. The engine is cached by the browser, so you can disconnect, reload and keep converting. That falls out of doing the work locally rather than being a separate mode you switch on.