Turn M4V files into Opus
Pull the sound out of your M4V and keep it as an Opus, leaving the picture behind. Opus gives you the best sound for the size of any common audio format, and handles speech and music equally well. The practical difference is that the result opens anywhere, which M4V files do not. Your file never leaves your computer.
How to convert M4V to Opus
- 1 Drop your M4V .m4v 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 Opus, or add more files and do the whole set in one go.
Why convert M4V to Opus
- An M4V will not open in a browser, so anything going onto a web page, into a document or into a message has to become an Opus first.
- You only want the sound: a lecture, an interview, a podcast that was filmed, or a track to listen to with the screen off.
- The best sound for the size of any widely supported format.
- Latency as low as 5 ms, suitable for real time.
- Audio tracks in WebM video.
M4V compared with Opus
How the two formats differ on the things that decide whether a conversion is worth making.
| Property | M4V | Opus |
|---|---|---|
| File extension | .m4v | .opus |
| Browser support | Some browsers | All current browsers |
| Introduced | 2005 | 2012 |
| Developed by | Apple | Xiph.Org and IETF |
| Standard | Proprietary | Open |
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 M4V. 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.
- Files protected with DRM cannot be decoded and will fail rather than convert.
- One Opus limitation to keep in mind: fewer editing tools handle it directly.
Questions about M4V to Opus
Will converting M4V to Opus lose quality?
A little. Both formats are lossy, so the file is decoded and compressed a second time and the two sets of artefacts add up. At a high quality setting the difference is hard to see, but avoid repeated round trips between lossy formats.
Does extracting the audio re-encode it?
Only when the target codec differs from the one in the M4V. 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 M4V file uploaded anywhere?
No. The whole thing runs inside the browser tab you already have open. Your M4V is read straight from your own disk, converted on your machine and handed back as an Opus. 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 M4V files at once?
Yes. Add as many as you like and they are processed one after another, then offered as separate Opus 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.