SOLIPSIUMAlpha

SOLIPSIUM Super resolution audio engine

Free video tool

Put a repaired or new sound track into your video, with the picture copied as it is.

Choose a video, then a sound file. Your browser copies the picture into a new MP4 and puts your sound with it, on your device.

Drop your video here

Then choose the sound to put in it. The video is not uploaded.

MP4, MOV, M4V, MKV or WebM with H.264, HEVC, VP9 or AV1 picture, up to 30 minutes.

Choose a video

How it works

From a video and a sound file to one MP4.

Your browser copies the picture's packets into the new MP4 and decodes only the sound.

Choose the video.

The page reads its picture format, size and length without decoding a frame. A silent clip works too.

Choose the sound.

Any sound file your browser opens, such as the WAV Solipsium's editor exports. Your browser decodes it at 48 kHz, or at the rate of the video's own sound when you mix the two.

The picture is copied and the sound encoded.

The new MP4 holds the same picture packets, and your sound is encoded beside them. The video's own sound is left out, or mixed under yours at the level you choose.

See what the sound needs.

The quick check listens to the first five minutes of your sound file 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 video.

Does the picture lose quality?

No. Its packets are copied into the new MP4, so it looks exactly as it did and takes the same space.

Which sound files go in?

Whatever your browser opens. WAV, MP3 and FLAC open in every current browser, and M4A in most. The sound is encoded as AAC, or as Opus where this browser has no AAC encoder; the page says which before you start.

What if the sound and the video are not the same length?

A longer sound is cut where the video ends. A shorter one leaves the end of the video silent, or you can cut the video where the sound ends. The page says which part is affected before you start.

Can I keep the original sound under the new one?

Yes. Choose Mix under and a level for the original, from -6 dB to -24 dB. Your browser decodes the video's own sound and adds it under yours, then turns the whole mix down if its loudest peak would pass -1 dBFS, and says by how much.

Why was my video refused?

Its picture is in a format this page cannot copy into an MP4, such as VP8, which the WebM to MP4 page converts first; it is longer than 30 minutes or larger than 10 GB; or your browser could not read it.

Can Solipsium repair the sound and put it back for me?

Yes, in Solipsium's editor, which needs a free account and imports videos up to 1 GB and 30 minutes. Repair the sound there and export the video: it keeps the original picture and carries the repaired track as AAC, in MP4 or MKV. This page is for a sound file you already have.

Is anything uploaded?

No. Your browser reads both files and writes the new video on your device. Only if you press Repair the first 20 seconds does any sound go to Solipsium: the first 20 seconds of your sound file, never the picture. Solipsium keeps only those 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.