YouTube, Instagram, TikTok and many other sites and apps take video, not sound files, so a song, a podcast episode or a voice memo has to become a video before it can be posted. This tool makes that video: your sound with a picture (or several, or a plain colour), the title and artist, and if you like a visualiser that moves with the sound. Free online converters upload the file, add a watermark or ask you to sign up; this one makes the MP4 on your computer, with none of that. It is free to use, with no account and no upload limit, and it runs entirely in your browser: nothing is uploaded, and while the page stays open, a feature you have already used keeps working offline.
- Is the sound quality kept?
- AAC sound, as in M4A files and iPhone voice memos, is copied into the video untouched. Other sound (MP3, WAV, FLAC and the rest) is encoded as AAC at 192 kb/s for stereo or 128 kb/s for mono, which keeps the quality of a typical MP3. MP4 videos almost always carry AAC sound, and it is what phones, computers and video sites expect.
- How long can the recording be?
- Up to 10 hours. The sound is read and written a piece at a time, so a two- or three-hour podcast does not fill the computer's memory. In Chrome and Edge, a video longer than an hour (or larger than about 400 MB) is saved straight to a file on disk as it is made. Other browsers build the whole video in memory first, which suits anything up to a few hours with a still picture. Sites and apps set their own limits on length and file size, so check theirs before a long upload.
- Why is the video so small, and so quick to make?
- A still picture does not need 30 frames a second: unless something moves, the video shows one frame a second, and each frame between the sharp key frames is almost nothing. An hour of sound with a still picture usually comes to little more than the sound itself. If a site or app turns the video down, choose 30 frames a second. A visualiser or progress bar makes frames that change, so they take longer to make and the file is bigger.
- Can I add a picture to an MP3 for YouTube?
- Yes. Drop the MP3 and the picture, keep the landscape 16:9 shape, and make the MP4; then upload it to YouTube like any video. If the MP3 has a cover picture in its tags, that is used unless you add your own.
- What is an audiogram, and can I make one here?
- An audiogram is a short video of a podcast or interview clip with a picture, the show's name and a moving waveform, made for social media where sound files cannot be posted. Choose a visualiser (bars or a waveform) and a portrait or square shape. To post just a highlight, cut that part out first with the Audio Trimmer.
- Which shape should I choose?
- Landscape 16:9 for YouTube and most screens; portrait 9:16 for Shorts, Reels and TikTok; square 1:1 or portrait 4:5 for posts in a feed. A picture of a different shape is fitted whole over a blurred copy of itself, or fills the frame with its edges cropped, as you choose.
- Which browsers work?
- The video is encoded by the browser, so it works in current versions of Chrome, Edge and Safari; Firefox may only manage 720p. Sound that the browser cannot read or encode itself (WMA, AIFF, AMR voice recordings, sound at unusual sample rates, or any sound in a browser without an AAC encoder) is converted by the site's own converter, which loads the first time it is needed.