MOV → MP3
MOV to MP3 converter
The audio track is extracted from the QuickTime container and re-encoded to MP3. The video track is discarded and never re-encoded, so the job is far faster than a video conversion.
…or drag files and folders here. Add as many as you like — everything is processed on this device.
.3g2 .3gp .m4v .mkv .mov .mp4 .qt .weba .webm
In one paragraph
MOV files from iPhones, DSLRs and screen recorders usually carry AAC audio, sometimes uncompressed PCM on professional cameras. You almost never want the video when you are after an interview, a lecture or a band’s soundcheck — you want a file that plays in a podcast app.
Sonic Batch demuxes the QuickTime atoms in a WebAssembly build of FFmpeg, throws away the video stream, and encodes only the audio to MP3. Because your video is often the largest file on your phone, the fact that it is never uploaded is not a privacy nicety — it is the difference between a 5-second job and a 40-minute one.
Does this change the audio quality?
If the MOV holds AAC audio this is a lossy→lossy transcode and you lose a second generation. If it holds PCM (common on Canon, Sony and Zoom recorders) it is a first-generation encode and the result is as clean as WAV → MP3.
- Only the first audio track is converted. Multi-track camera files keep track 1 and report the others as skipped.
- A silent MOV produces no output and is marked as unsupported rather than written as a silent MP3.
- Large 4K files are rejected above the 400 MB per-file budget. Trim the clip in your video app first, or use the audio-only export your camera app already offers.
A worked example
Turning a two-camera interview shoot into editable audio
- Drop both MOV files into the queue. Sonic Batch shows the detected audio codec, sample rate and duration for each.
- Set 192 kbps stereo for the room camera and Podcast/voice (mono, −16 LUFS) for the lapel-mic camera.
- Press Convert all — the video streams are skipped, so both jobs finish in a fraction of the clip length.
- Download the two MP3s individually and drop them straight into your editor.
Match the bitrate to what the camera recorded
Cameras typically record AAC at 128–256 kbps. Encoding that to a higher MP3 bitrate cannot add information back, so 192 kbps is the sensible ceiling for AAC sources and anything above 256 kbps is wasted bytes. If your camera recorded PCM, treat it like a WAV source and use 256–320 kbps for music.
Supported formats, limits and browser notes
Sonic Batch decodes with the browser when it can (faster, no engine download) and falls back to the self-hosted WebAssembly engine when it cannot. Every combination below works in every listed browser; the column only tells you which decoder does the work.
| Input | What it is | Chrome | Firefox | Safari | iOS |
|---|---|---|---|---|---|
| MOV | QuickTime video from iPhone and DSLR cameras. Audio is normally AAC or PCM. | Partial | Engine | Native | Native |
| MP4 | The standard video container. Its audio track is almost always AAC. | Native | Partial | Native | Native |
| WebM | Open container used by browser recorders and YouTube downloads. Audio is Opus or Vorbis. | Native | Native | Partial | Partial |
| 3GP | Legacy phone recording container, normally AMR-NB or low-bitrate AAC audio. | Engine | Engine | Partial | Partial |
| Output | Encoder | Bitrates / depth | Sample rates | Tags |
|---|---|---|---|---|
| MP3 | libmp3lame | 32–320 kbps | 8–48 kHz | Yes + artwork |
- Max per file
- 400.0 MB
- Max per queue
- 4.00 GB
- Max duration
- 4:00:00
- Max archive
- 1.50 GB
These are enforced ceilings, checked before any decoding starts, not measured maximums — a file over the limit is rejected rather than allowed to exhaust the tab’s memory. Real-world capacity is lower on older phones, which is why the scheduler runs one file at a time on iOS and Safari.
Where your audio goes
Nowhere. Your file is read from disk into this browser tab with the File API, decoded and encoded by code running in that same tab, and handed back to you as a download. It is never transmitted.
That is a structural property of the application, not a policy promise: there are no API routes, no server actions and no third-party processing services in this project, so there is nothing capable of receiving a file. The page’s Content-Security-Policy also restricts connections to this origin, and the automated test suite includes a browser test that fails if any network request during import, preview, conversion or download carries media bytes.
The trade-off, stated plainly:results live in your tab’s memory until you download them. Closing or reloading the page discards them. There is nothing on a server to recover, because nothing was ever put there.
Troubleshooting
The file loads but the duration shows as unknown.
Some cameras write a MOV with the moov atom at the end of the file, and a few write it incorrectly after a battery pull. Sonic Batch still converts the audio but cannot show a duration or a reliable progress percentage until the engine reaches the end of the stream.
It says no audio stream found.
Screen recordings made without microphone or system-audio permission genuinely contain no audio track. Check the clip in a player first — if it is silent there, there is nothing to extract.
Firefox will not preview the MOV before conversion.
Firefox has no QuickTime demuxer, so the browser cannot preview it. Conversion still works because the WASM engine does not depend on the browser’s decoders.
Frequently asked questions
Does this convert the video too?
No. This is an audio utility: the video stream is dropped and never encoded. If you need a video conversion, this is not the tool.
Will the MP3 be in sync with the video?
The audio is extracted from the start of the track, so it lines up with the video timeline. If your camera recorded with an audio delay, that delay is preserved rather than corrected.
Can I do this on an iPhone?
Yes. Pick the MOV through the Files or Photos picker in Safari. iOS runs the single-threaded engine and one file at a time, and very long 4K clips may hit the memory budget — a 10-minute clip is comfortable, an hour-long one is not.
Does it work with MP4 as well?
Yes. MOV and MP4 share the same ISO base media structure and this page accepts both, plus WebM and 3GP.