Online tools New Zealand
Audio to Video Converter
Platforms such as social networks and video sites want video, not audio. This tool puts your audio over a cover image or colour with animated sound bars and records the result as a video file, using nothing but your browser. Built for New Zealand users, with nothing sent to a server.
Free, no signup Runs in your browser
Result
—Format
—
Duration
—
Progress
—
Your video
How do I turn an MP3 into a video?
Choose the audio file, add a cover image and an optional title, pick a shape and press Make video. The tool plays the audio while drawing the picture and sound bars on a canvas and records both together, so the video takes as long as the audio to make. The file is WebM in most browsers and MP4 in browsers that can record it.
What you get
The video shows your image (or the background colour), the title and a row of bars that move with the sound. It is a simple look aimed at podcasts, music and voice recordings for platforms that do not take audio. You get the image's aspect ratio preserved, centred and not cropped.
For richer videos, editing software gives more control, but those need an upload or a download.
Recording notes
Keep the browser tab visible while the video records, since some browsers slow background tabs and the animation may stutter. Your device's speakers play the audio while recording; the recording itself is taken directly from the audio stream, so room noise does not get in.
To convert the audio to a different format first, use the MP3 to WAV converter.
How this is calculated
The rule, step by step, so you can check any figure by hand.
the audio plays through the browser's audio engine into an analyser and a recording streama canvas draws the cover image, title and sound bars at 30 frames a secondthe canvas stream and the audio stream are recorded together by the browser's media recorderrecording time = audio length, because the file is made as the audio plays
There is no way to speed this up: the browser records what plays, so a ten-minute audio file takes ten minutes. That is the cost of doing it without a server or a large video library, and it is why the tool shows progress and has a Stop button.
The video format depends on the browser. Chrome and Firefox record WebM, which plays on most platforms and uploads to most video sites, and recent Chrome and Safari can record MP4. If a platform rejects WebM, convert it with desktop software.
A worked example
A 5-minute audio file with a square cover image and a title.
- Time to makeabout 5 minutes (real time)
- FileWebM or MP4, about 15 to 40 MB
- Shape1080 × 1080
A square video ready to upload.
Keep the tab open while it records.
Privacy
The audio and image stay on your device. If the audio is an interview, or contains other people's voices, keeping it local suits obligations under the Privacy Act 2020.
What it leaves out
There is no waveform styling beyond bars, no subtitles and no trimming. The recorder's format cannot be chosen: it uses the best your browser offers.
What this calculator does not do
- Records in real time
- Output is WebM or MP4 depending on the browser
- Simple bar visualiser only
- Needs a browser with the MediaRecorder feature
Common questions
Does it upload my audio?
No. The audio, image and video stay in your browser.
Why does it take as long as the audio?
The browser records the video as the audio plays, so it runs in real time.
What format is the video?
WebM in most browsers, or MP4 where the browser can record it.
Can I use it for a podcast on a social platform?
Yes. Square and vertical shapes suit most social feeds.
Why is it not working on my phone?
Some mobile browsers do not support canvas recording. Try a desktop browser.
Where these numbers come from
- MDN — MediaRecorder API How browsers record audio and video streams
- MDN — HTMLCanvasElement.captureStream Recording a canvas as a video stream
- Office of the Privacy Commissioner New Zealand's privacy regulator, for the Privacy Act 2020
Method last reviewed 2026-10-28 This calculator uses fixed rules rather than rates that change, and its method is re-checked against the sources above at least once a year. Out of date? Tell us and we will fix it.
Related NZ calculators
MP3 to WAV
Convert audio to WAV without uploading it.
Open calculator Online toolsVoice recorder
Record audio and download it, privately.
Open calculator Online toolsScreen recorder
Record your screen and download the video.
Open calculator Online toolsText to speech
Read text aloud with your device's voices.
Open calculator