MP3 to MP4 Converter

YouTube, Instagram, Facebook and most video platforms do not accept plain audio files. This tool wraps your MP3 (or WAV, M4A, AAC, OGG, FLAC) in an MP4 video with a still picture: your own image, the album art already inside the MP3, or a colour or gradient background with the track title. The picture is encoded once and repeated, so the time goes almost entirely into the sound: M4A and AAC audio is copied in seconds, and MP3 or other formats are converted at roughly 5 seconds per minute of audio on a computer. Everything runs in your browser; nothing is uploaded.

How to use this tool

1. Optionally choose a picture first; otherwise the embedded album art or a background is used.
2. Pick the size, colours and title, then choose one or more audio files — each becomes a video.
3. Use 1920 × 1080 for YouTube, square or vertical for social media.
4. Check the frame preview and download the MP4; change a setting and press Calculate to make it again.

Formula

Video length = audio length; video = 5-second still segment repeated, audio copied (AAC) or encoded to AAC 192 kbps

The still picture is encoded as five seconds of H.264 at 25 fps with a keyframe every five seconds, then repeated without re-encoding for the length of the audio, so a long file costs no more picture work than a short one. AAC audio (M4A, AAC) is copied unchanged; MP3, WAV, FLAC and others are encoded to AAC at 192 kbps, the format MP4 players expect.

Example

A 58-minute podcast MP3 at 128 kbps (about 53 MB) with the show logo at 1920 × 1080 becomes an MP4 of roughly 85–90 MB: about 83 MB of AAC sound at 192 kbps plus a few MB for the still picture. The picture takes seconds; converting the MP3 sound to AAC takes most of the time — about 50 seconds per 10 minutes of audio on a computer, so roughly 5 minutes for this episode.