AVI → MP3
AVI to MP3 converter
The AVI’s audio track (usually MP3, PCM, ADPCM or AC-3) is decoded and re-encoded to MP3, and the video is left behind. A PCM or ADPCM source gives a first-generation MP3; an MP3 source loses a little more.
…or drag files and folders here. Add as many as you like — everything is processed on this device.
.asf .avi .f4v .flv .m4v .mk3d .mka .mkv .mov .mp4 .qt .wmv
In one paragraph
AVI was the standard video format of the 1990s and 2000s: early digital cameras, MiniDV capture cards, webcams and the whole DivX and Xvid era wrote it. Family videos, school plays and old recordings often survive only as AVI files that modern phones and browsers refuse to open. Extracting the audio is a quick way to keep the voices and music in a format that plays everywhere.
No browser can read AVI, so Sonic Batch uses a WebAssembly build of FFmpeg that runs in your tab. It handles the audio codecs AVI files actually contain, including the 8-bit PCM and IMA ADPCM used by old cameras, MP3 in DivX files, and AC-3 in later rips, and it ignores the video stream entirely, including MJPEG camera footage.
Does this change the audio quality?
MP3 is lossy. For camera AVIs with PCM or ADPCM sound this is a single, first-generation encode. For DivX and Xvid files that already carry MP3, re-encoding loses one more generation, so do not raise the bitrate above the source.
- Old camera audio is often 8 to 22 kHz mono. Converting to 44.1 kHz stereo makes the file bigger without adding any detail.
- Only the first audio track is extracted.
- A damaged AVI index (common after an interrupted capture) can make the duration show as unknown, but the audio usually still converts.
A worked example
Saving the audio from a box of old digital camera clips
- Copy the AVI files off the memory card or old drive and drop the folder into the queue.
- Choose 128 kbps and set Channels to mono: early cameras recorded one microphone.
- Turn on loudness normalization so quiet and loud clips play back at a similar level.
- Convert all and download the ZIP.
Low bitrates are fine for old camera audio
Most cameras that wrote AVI recorded mono sound at 8 to 22 kHz, which carries far less detail than a CD. A 96 or 128 kbps mono MP3 captures all of it. Keep 192 kbps stereo for AVI files with music soundtracks, such as DivX movie rips, and never exceed the bitrate of an MP3 track that is already inside the AVI.
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 |
|---|---|---|---|---|---|
| AVI | Legacy Windows video container from camcorders, older cameras and DivX/Xvid files. Audio is usually MP3, PCM or AC-3. | Engine | Engine | Engine | Engine |
| WMV | Windows Media video in an ASF container. Audio is almost always WMA (Windows Media Audio). | Engine | Engine | Engine | Engine |
| 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 |
| MKV | Open video container used for films, TV recordings and OBS captures. Audio is often AAC, AC-3, DTS, Opus or FLAC. | Partial | Partial | Engine | Engine |
| FLV | Flash-era web video, still produced by some stream recorders. Audio is AAC or MP3. | Engine | Engine | Engine | Engine |
| 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 audio sounds very quiet.
Old camera microphones recorded at low levels. Enable loudness normalization on this page; it measures the clip and raises it to a consistent level before encoding.
It says no audio stream was found.
Some AVI files, especially time-lapses and screen captures, have no sound at all. Check the file in VLC; if it is silent there, there is nothing to extract.
The duration shows as unknown.
Browsers cannot read AVI, so the duration appears only after the engine has opened the file. A missing or damaged index can also hide it; conversion still works.
Frequently asked questions
How do I convert AVI to MP3?
Drop your AVI files above, pick a bitrate, and press Convert all. Each MP3 downloads individually or in a ZIP.
Why will my browser not play AVI files?
No modern browser includes an AVI demuxer. Sonic Batch brings its own engine, compiled to WebAssembly, so the file can still be read without installing anything.
Are my videos uploaded?
No. Everything is processed in your browser. Family videos stay on your device.
Can I get WAV instead of MP3?
Yes. Open the batch converter, add the AVI files, and choose WAV as the output.