Choose your recording.
A WebM from a screen recorder or a browser, or an MKV. Your browser reads its tracks without decoding the picture and works out its length from the recording itself.
SOLIPSIUM Super resolution audio engine
Free video tool
Convert a WebM screen or browser recording to MP4.
Choose Compatible for an MP4 with H.264 picture and AAC sound, or Copy to move VP9 picture and Opus sound into an MP4 as they are. Your browser writes the MP4 on your device.
Drop your WebM recording here
It is converted in your browser. The recording is not uploaded.
WebM or MKV.
Convert your recording
Make
Your MP4
Your first 20 seconds
After signing up, import the recording into the editor: it repairs the whole soundtrack and exports the video with its picture kept.
What Solipsium hears
Make a free account to repair the whole soundtrack
Then import the recording into the editor. Scans and short repairs are free.
How it works
From a WebM recording to an MP4.
An MP4 can hold the VP9 picture and Opus sound that browser recordings often use, and some players refuse them in an MP4. The page can copy them as they are, or re-encode them as H.264 and AAC.
Compatible makes H.264 and AAC.
Your browser decodes every frame and encodes it again as H.264, with the setting the video enhancer uses; a picture already in H.264 is copied. The sound is converted to AAC, or kept as Opus where this browser has no AAC encoder. The page starts on Compatible when this browser can make it from your recording, and on Copy when it cannot.
Copy moves it as it is.
VP9 and AV1 picture and Opus sound go into the MP4 packet for packet, in far less time than a re-encode. Older VP8 picture and Vorbis sound, which few MP4 players play, are re-encoded even on Copy.
See what the sound needs.
The quick check listens to the first five minutes for clipping, dropouts, hum, background noise and muffled sound. You can then hear its first 20 seconds repaired, with no account. Solipsium's free try is built for speech.
Questions
Before you choose a recording.
Why does my WebM not play in some apps?
A WebM holds VP8 or VP9 picture and Opus or Vorbis sound, and some phone apps and video editors open only H.264 and AAC. Compatible makes those.
Why does my recording show no length?
A recording written while it is being made, as a browser's recorder writes it, often has no length in its header, so some players show none. Both choices write an MP4 whose header gives its length.
Copy or Compatible?
Choose Copy when the MP4 will play in a browser or a player you know reads VP9 and Opus; it takes less time. Choose Compatible for an app, editor or upload form that wants H.264 and AAC; it takes longer, since every frame is decoded and encoded again.
Does converting lose quality?
When the packets are copied, nothing is lost: the MP4 holds the same ones. A re-encode compresses the picture again with the H.264 setting the video enhancer uses, and loses a little detail.
How long a recording can it take?
Copy takes any length when your browser writes straight to a file, which Chrome and Edge do; other browsers write the MP4 into their storage for this site, or into memory, which holds about 200 MB. Compatible takes recordings up to 1920 x 1080, 60 frames a second and 30 minutes, in ordinary 8-bit colour.
Is my recording uploaded?
No. Your browser reads the WebM and writes the MP4 on your device. Only if you press Repair the first 20 seconds does any sound go to Solipsium, never the picture, and Solipsium keeps only its first 20 seconds and deletes them within an hour.
Make an old recording easier to hear.
Solipsium works on voicemails, voice memos, answering machine tapes and camcorder audio.
Try it on a recording
The check and the 20-second try need no account.