MP3 to MP4 converter
Put a picture to an MP3 and get an MP4 you can upload to YouTube or social apps.
Runs in your browser. Nothing is uploaded.
Drop the audio
MP3, M4A, WAV or any audio your browser can play. It stays on your computer.
Add a picture (optional)
Cover art or a photo. Without one, the video is black.
Video shape
No picture: the video will be black.
More about this tool
- 1
Add the audio
An MP3, M4A, WAV or any audio your browser plays.
- 2
Add a picture and pick the shape
Cover art or a photo, fitted inside the frame. 16:9 for YouTube, 9:16 for Shorts and Reels.
- 3
Make the MP4 and download
Play it to check the sound, then download it.
Video sites and apps take video files, so a song, a podcast episode or a voice-over needs a picture to go up. The MP4 shows the picture for the whole length of the sound.
The picture is fitted inside the frame without cropping. A square cover in a 16:9 frame gets black bars at the sides; a photo of the frame's shape fills it.
The picture is encoded as H.264 at one frame a second, which is all a still picture needs and keeps the video track tiny. Most of the file is the sound: up to about 1.4 MB a minute.
The sound is encoded to AAC at 192 kbps. YouTube's formatting specifications ask for AAC at 128 kbps or better in an MP4, so it's above that.
The same video on the command line. -tune stillimage tells the H.264 encoder the picture doesn't move:
- ffmpeg -loop 1 -framerate 1 -i cover.jpg -i song.mp3 -c:v libx264 -tune stillimage -pix_fmt yuv420p -c:a aac -b:a 192k -shortest song.mp4
Sources
Questions
No. The sound and the picture are encoded into the MP4 in your browser. Nothing is sent anywhere.
No. Without one the video is black, with the sound as it is.
16:9 for a regular YouTube video, 9:16 for Shorts, Reels and TikTok, 1:1 for a square post.
It's encoded once more, to AAC at 192 kbps, which keeps music close to a typical MP3. Video sites encode it again after upload anyway.
The MP4 is built in your browser's memory, so very long recordings may not fit. An hour comes to about 90 MB, which most computers handle.
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