Downmix a stereo recording to mono locally (channel average) - halves WAV file size and fixes one-sided recordings, no upload.
Running locally on your device ...
Running locally on your device ...
0%
Your files never left your device
No. Everything runs in your browser - your file never leaves your device. How this is verifiable
Speech recordings, call captures and podcasts rarely need two channels - mono halves the uncompressed file size and sounds identical on every device. It also fixes the classic "microphone only on the left channel" problem: the content sits evenly on both ears.
The downmix is the standard average of both channels (L+R divided by 2), applied right on the PCM samples. Multi-channel material (e.g. 5.1) is averaged to one channel too. Out-of-phase content can physically cancel - irrelevant for normal recordings.
Conversion runs fully in the browser: decode, average, re-encode (WAV or M4A) - the file never leaves your device.
| Input formats | MP3, WAV, M4A, AAC, OGG, OPUS, FLAC |
|---|---|
| Auto-conversion | MP4 |
| Output formats | WAV, M4A |
| Batch processing | No |
| Processing | Locally in your browser (WebCodecs) |
| File upload | None |
Limitations: Honest per-device length cap (desktop about 20 minutes, tablet 15, phone 10; more with plenty of memory). Equal-weight average (no adjustable channel ratio); exactly out-of-phase signals cancel when averaged - physics, not a malfunction. The file is fully decoded and re-encoded as a fresh WAV or M4A; ID3 tags and an embedded cover are always lost in the process, since there is no tag writer. WAV is lossless here, M4A (AAC) is lossy. Compressed inputs need the browser WebCodecs decoder.
No, everything stays local in the browser.
Standard average: (left + right) / 2 per sample. Preserves loudness and never clips.
As WAV: yes, half the size (one channel instead of two). For M4A it depends on encoding, usually clearly smaller.
Yes. After the downmix, the single channel content sits evenly on both ears.
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