The file's own rate is read.
The rate comes from the file's header, read with mediabunny before anything is decoded.
SOLIPSIUM Super resolution audio engine
Free audio tool
Change a recording's sample rate, adding no treble.
Resample a WAV, an MP3 or any file your browser opens to 48, 44.1, 32, 22.05, 16 or 8 kHz, and save it as a WAV or an MP3. The page shows the file's own rate first.
Drop a recording here
Your browser resamples it on this device. It stays on your device until you ask for a repair.
WAV, MP3, M4A, FLAC, Ogg and more, up to 30 minutes or 200 MB.
Ready to resample
Is the recording itself clear?
A rate change does not clean the sound. Solipsium's free try is built for speech: the check below looks in your browser for background noise, hum, clipping, dropouts and muffled sound, and you can hear the first 20 seconds of a voice recording repaired with no account.
For speech saved at 16 kHz, the try can rebuild the treble above 8 kHz when nothing else is found, or only steady noise. It keeps the recording's own sound below 8 kHz, and what it adds is labelled inferred.
Your first 20 seconds
After signing up, drop the same file into the editor to repair all of it.
What Solipsium hears
Make a free account to repair the whole recording
Then drop the same file into the editor. Scans and short repairs are free.
How it works
Your browser resamples the file in one step.
Your browser decodes the file straight to the rate you choose. A recording holds sound up to half its sample rate, so a lower rate cuts the top, and a higher rate holds nothing above what was recorded.
It is decoded at the new rate.
Your browser's Web Audio decoder opens the sound and resamples it to the rate you chose, on this device.
You save a WAV or an MP3.
The WAV holds 16-bit samples and every channel. The MP3 is made with lamejs, a JavaScript port of LAME, under the GNU LGPL: 192 kbps at 32 kHz and over, 128 kbps at 16 to 22.05 kHz, and 64 kbps at 8 kHz, the highest an 8 kHz MP3 can carry.
The header is read with mediabunny 1.61.1, under the Mozilla Public License 2.0, served exactly as it is published; its source is on GitHub and its licence is here.
Questions
Before you resample.
Does 48 kHz sound clearer than 44.1 kHz?
Not by itself. 44.1 kHz already holds sound up to 22.05 kHz, above what adult ears hear. Video projects usually run at 48 kHz and CD audio at 44.1 kHz, so choose the rate your project or upload form asks for.
Can a higher rate bring back treble that was lost?
No. A file saved at 16 kHz holds nothing above 8 kHz, and at 48 kHz it still holds nothing above 8 kHz. For speech saved at 16 kHz, the free try can rebuild that treble and labels what it adds as inferred. Audio upscaler says when it runs.
What bit depth is the WAV?
16-bit, the depth of a CD, whatever the original was. A 24-bit file is written as 16-bit.
Down to 8 or 16 kHz for a phone system?
Choose 8 kHz or 16 kHz and save a WAV. At 8 kHz the file keeps sound up to 4 kHz, about the range of a phone call. The WAV keeps the file's channels, so a stereo file stays stereo; Stereo to mono folds it to one channel.
Which resampler does this use?
Your browser's own Web Audio OfflineAudioContext decodes the file straight to the new rate, and nothing else processes the sound.
Is my file uploaded?
Not to resample it. Your browser reads, resamples and saves the file on this device, and Solipsium's check of the recording runs in your browser too. Audio is sent only if you press Repair the first 20 seconds. For a mono or stereo recording of up to five minutes, only its first 20 seconds leave this browser; Solipsium repairs them on its server and deletes them within an hour. A longer file would have to go whole, so the try is offered for it only up to 25 MB, and Solipsium keeps just its first 20 seconds.
A muffled voice recording?
Drop it on the home page. The check runs in your browser, and you can hear its first 20 seconds repaired with no account.
Check a recording
The check and the 20-second try need no account.