SOLIPSIUMAlpha
SOLIPSIUM Super resolution audio engine
Free audio tool
Turn a WAV, FLAC or AIFF file into an MP3 in your browser. Before you download it, the page shows the file's sample peak, true peak and loudness, and warns you when the peaks leave the MP3 no room.
Drop a WAV or FLAC here
Your browser measures and converts it on this device. It stays on your device until you ask for a repair.
WAV, FLAC or AIFF, up to 30 minutes or 500 MB. AIFF files open in Safari.
Normalize audio sets a file's loudness under a true-peak ceiling in your browser. Turn the file down there or in your editor, then bring it back here.
The MP3 folds this file's channels into stereo, the way Web Audio folds them for two speakers, or into one channel when you choose Mono.
Converting does not clean the sound. Solipsium's free try is built for speech: the check looks in your browser for background noise, hum, clipping, dropouts and muffled sound, and you can hear the first 20 seconds of a mono or stereo voice recording repaired with no account.
The check in your browser hears recordings of up to five minutes. For a longer one, make a free account: the editor scans recordings up to 30 minutes.
After signing up, drop the same file into the editor to repair all of it.
Then drop the same file into the editor. Scans and short repairs are free.
How it works
A WAV or FLAC file holds the samples exactly as they were saved. An MP3 leaves some sound out to save space, and its encoder can push a peak that sits close to full scale over it, so the page reads the peaks before it makes the MP3.
The page reads the header for the rate and bit depth the file was saved at. Then your browser decodes the sound on this device: at 48 kHz for a file saved at 48, 96 or 192 kHz, and at 44.1 kHz, the CD rate, for anything else.
Sample peak is the largest sample. True peak is read four times oversampled, which finds peaks that fall between samples. Loudness is integrated loudness in LUFS, by ITU-R BS.1770, with the meter the loudness checker uses.
The MP3 has a constant bitrate: 192 kbps unless you choose 128, 256 or 320. A higher bitrate keeps more of the sound in a larger file. MP3 files are made with lamejs, a JavaScript port of LAME, under the GNU LGPL.
Questions
192 kbps is the default, and it is the lowest bitrate ACX accepts for audiobook MP3s. 256 or 320 kbps keeps more of the sound in a larger file. 128 kbps makes the smallest file and loses the most.
An MP3 carries 48 kHz at most, so a file saved at 96 or 192 kHz is decoded at 48 kHz, and one saved at 88.2 kHz at 44.1 kHz. An MP3 has no bit depth of its own: the encoder works from the decoded samples, whatever depth the WAV had. The panel shows what the file was saved at.
The loudest samples reach the top of what the file can hold. Encoding changes the shape of the wave slightly, so peaks that close can come out over full scale in the MP3 and clip when it plays. Turn the file down by at least 1 dB first, with Normalize audio or in your editor. When only the true peak is above -1 dBTP, the page says how far to turn it down.
FLAC files open in every current browser. AIFF files open only in Safari, so use Safari on a Mac or an iPhone for those. The page reads the rate and bit depth from WAV, FLAC and AIFF headers alike.
A little. An MP3 leaves out some sound to save space, and a lower bitrate leaves out more. Your WAV or FLAC is not changed: the page reads it and saves the MP3 as a new file in your downloads.
Not to convert it. Your browser measures and converts the file on this device, and Solipsium's check of a spoken recording runs in your browser too. Audio is sent only if you press Repair the first 20 seconds. Then only the recording's first 20 seconds leave this browser; Solipsium repairs them on its server and deletes them within an hour.
Drop a spoken recording on the background noise page. The check runs in your browser, and you can hear its first 20 seconds repaired.
The check and the 20-second try need no account.