Audio to video, with a moving waveform.

An audio to video converter puts a sound file into a video file, so it can go where only video is taken. This one starts from a moving waveform on a colour of your choice, which is what most recordings need when there is no picture. Add a title, pick a wide, square or tall frame, and make an MP4 in your browser. It reads WAV, M4A, FLAC, OGG, AAC and MP3 files, and it can take the sound out of a video file. Nothing is uploaded and nothing is added to the video.

How to convert audio to video

1. Drop your recording on Drop a sound file here, or click to choose. Several files are joined in the order shown.
2. Under Video look, keep Waveform on a colour, or choose a picture look and use Choose a picture.
3. Set Background, Waveform colour, and a Title and Second line if you want words on screen.
4. Pick the Shape. Move the slider under the preview to check a loud moment.
5. Press Make the video, then Download the MP4.

The waveform

Two styles are offered. Bars that move with the sound splits the sound into bands from low to high and draws one bar for each, so bass shows on the left and treble on the right. A line that follows the sound draws the shape of the sound itself, like an oscilloscope. Both are worked out from the file, so the preview and the video match. The bars fall back softly after a loud moment instead of flickering.

Which files work

Any sound the browser can read: WAV, M4A, FLAC, OGG, AAC, MP3 and the sound track of an MP4 or MOV file. WAV files are large because they are not compressed. Stereo 16-bit sound at 44,100 samples a second needs 44,100 x 2 x 2 = 176,400 bytes a second, which is about 10.6 MB a minute. In the MP4, the sound is AAC at 192 kbps, which is 1,440,000 bytes a minute, about 1.4 MB. So a ten minute WAV of about 106 MB comes out around 14 MB of sound.

Worked example: a meeting recording

You have a 40 minute recording and want a 5 minute highlight with a title card. Waveform videos can be up to 12 minutes, so set Start at (s) to 600 and End at (s) to 900. That keeps 300 seconds, which is 5:00. Type the meeting name in Title, choose the square shape, tick Fade the sound out at the end and make the video. At 30 frames a second, a five minute video has 300 x 30 = 9,000 frames, and every one is drawn, so choose 15 frames a second if you want it done sooner.

Picture or waveform?

A recording without a picture looks best as a waveform on a colour. Music with artwork looks best with the picture. A podcast episode works well with the artwork as the picture and a title on the waveform look. The picture only look is the fastest to make and has no length limit, so it suits long recordings.

Common problems

• The file cannot be read. Some codecs are not opened by the browser. Convert it first with the audio converter.
• The waveform is limited to 12 minutes. Trim with Start at and End at, or choose Picture only.
• The bars are small. A very quiet recording makes small bars. The tool raises the level for you, up to a point.
• The browser cannot encode video. Use a current Chrome, Edge or Safari.

For a picture and sound only, see MP3 to MP4. For a titled clip with captions, try the audiogram maker.