How to convert MIDI to MP4 in your browser (no upload, no install)

The fastest free way to convert MIDI to MP4 is to open midee, drop in a .mid file, pick a theme and resolution, and click Export. The browser renders an H.264 MP4 piano-roll video with audio baked in — locally, no account, no upload, no watermark. A typical 3-minute track finishes in under a minute on any recent laptop.

This guide walks the full MIDI-to-MP4 workflow, explains exactly how the conversion works under the hood, and compares the browser-export route against screen recorders, paid desktop tools, and upload-based converters. If you only want to listen to a MIDI without exporting video, use the online MIDI player instead.

What does "MIDI to MP4" actually mean?

A MIDI file stores musical performance data — note pitches, velocities, timing, tempo, and control changes — but no audio and no video. To share that performance on YouTube, TikTok, Instagram, or Discord, you need to render it into a format every player understands: an MP4 with audio you can hear and a piano roll you can watch. That render is the "MIDI to MP4" conversion.

It is fundamentally different from "MIDI to MP3," which produces only audio. MP4 is the right format when you want viewers to see the notes move.

How do I convert a MIDI file to MP4 for free?

1. Open midee in Chrome 94+, Safari 16.4+, or Firefox 130+ — these are the browsers with VideoEncoder (WebCodecs) support.
2. Drag any .mid or .midi file onto the page, or click to browse.
3. Press play to preview the piano-roll visualization in real-time.
4. Pick a theme (Dark, Neon, Sunset, Ocean), an instrument voice, and a particle style.
5. Click Export in the top-right toolbar.
6. Choose a preset: 720p, 1080p, vertical 9:16, square 1:1, or your native canvas size.
7. Click Start — the MP4 saves to your Downloads folder when rendering finishes.

That is the entire workflow. Your MIDI file, the rendered audio, every video frame, and the final MP4 stay on your device the whole time. There is no upload, no signup, no paid tier, no watermark.

How does midee actually encode MIDI to MP4?

If you have been burned by lossy converters or watermark-laden web tools, the technical pipeline matters. midee uses the browser's native WebCodecs API and Mediabunny (an MP4 muxer) — no FFmpeg-in-WASM, no server, no transcoding round-trip.

The export runs in this exact order:

1. Parse the MIDI with @tonejs/midi to extract note events, tempo map, and control changes.
2. Render the audio offline through a sampled piano (or whichever instrument you pick) at 44.1 kHz, faster than real-time.
3. Encode the audio first to AAC-LC at 192 kbps in ~4096-frame chunks, so the muxer has every audio packet before the video loop begins.
4. Render each video frame with Pixi.js (WebGL) to a canvas at the chosen resolution.
5. Encode video through VideoEncoder at H.264 High Profile level 5.2 (4K @ 60 fps) if the hardware supports it, falling back to 5.1 / 5.0 / 4.0 / Main 3.1 / Baseline 3.1 as needed. Default video bitrate is 8 Mbps, default frame rate is 30 fps, with a 2-second keyframe interval. The encoder runs in latencyMode: 'realtime' — about 1.5–2× faster than quality mode at the same bitrate, with no perceptible quality loss at the bitrates we target (YouTube re-encodes anyway).
6. Mux the encoded video and audio into an MP4 with fastStart: 'in-memory', so the moov atom lands at the front of the file and the result streams cleanly in browsers and on social uploads.

Hardware acceleration is preferred whenever the platform offers it — on M-series Macs and recent Intel / AMD machines, 1080p typically encodes faster than playback. If the browser does not support WebCodecs, midee throws an explicit error instead of producing a corrupt file.

For the longer engineering story (and why this beats the previous ffmpeg-wasm pipeline by a wide margin), read why I replaced ffmpeg.wasm with WebCodecs.

What resolution should I export?

Match the export resolution to where the video will live. midee defaults to 1080p — it's the safest landscape choice on every major platform — but short-form feeds require 9:16.

A 3-minute MIDI at 1080p / 30 fps with hardware-accelerated H.264 typically finishes in 30–60 seconds on a recent laptop. The same MIDI at 4K can take 3–5× longer because the encoder is moving roughly 4× the pixels per frame.

MIDI to MP4 vs MIDI to MP3 — which one do you want?

• MP4 when you want viewers to see the performance — a piano-roll video that scrolls while it plays. This is what social platforms reward; nobody watches a static waveform on TikTok.
• MP3 or M4A when you only need audio — a SoundCloud upload, a podcast bed, or background music. midee has an audio-only export mode that skips the entire video pass and muxes the same AAC track into an .m4a. It is 10–20× faster than MP4 export because no frames need to be rendered.

If you need both, run the MP4 export and use any audio extractor (or VLC's "convert and save") to pull the audio track. It is the same AAC-LC stream either way.

Why not just screen-record Synthesia or MIDIano?

Screen recording works, but it stacks tools and failure modes. You set up Synthesia (or MIDIano, or Piano from Above), launch OBS or QuickTime, capture, trim the silence at the start and end, verify the audio is in sync, and re-render if it isn't. A single dropped frame from the recorder produces a visible stutter that cannot be fixed in post. Audio passes through your system mixer, which can clip or pick the wrong device.

The browser-export route sidesteps all of that. Frames are rendered at exactly 30 fps with timestamps driven by the MIDI clock, so there are no dropped frames — nothing is being captured in real time. Audio comes from the same offline render that produced the audio buffer, so it stays sample-accurate to the visuals.

That said: if you want cinematic camera moves, slow-motion freezes, hand-animated flourishes, or multi-MIDI medleys, a desktop tool like SeeMusic will still produce more polished output. midee is optimized for "drop in MIDI, get a clean MP4 in a minute" — not for color-graded music videos.

MIDI-to-MP4 workflows compared

For most musicians, the browser-export workflow eliminates four out of the five typical steps.

When midee is the wrong choice

A useful list — the limits are real and worth knowing before you invest time:

• Very long MIDIs on weak hardware. A 30-minute track at 4K on a low-power tablet will take a long time. Drop to 720p or move to a laptop.
• Custom motion graphics or lyric tracks. midee renders one piano roll per export. Multi-layer compositing belongs in After Effects, DaVinci Resolve, or Premiere.
• MusicXML / sheet-music export. midee renders a piano-roll view, not notation. Render the MP4 here and the score in MuseScore or Noteflight if you want both.
• Older browsers. Firefox 129 and earlier do not implement VideoEncoder. midee will return a clear error rather than silently produce a broken file — update the browser or switch to Chrome.

Common questions

Is midee really free for MIDI-to-MP4 conversion? Yes. midee is open source under the MIT license, runs entirely in your browser, and has no paid tier, watermark, or signup.

Does midee upload my MIDI file to a server? No. Parsing, audio rendering, video encoding, and MP4 muxing all happen locally in your browser tab. Network traffic during export is zero — you can disconnect from the internet and the export will still finish.

Will the exported MP4 include audio? Yes. midee renders your chosen instrument offline at 44.1 kHz, encodes it to AAC-LC at 192 kbps, and muxes it into the MP4 alongside the video. The file is ready to upload directly.

Can I export 4K MIDI videos? Yes, when your hardware supports H.264 High Profile level 5.2. midee probes available codec profiles at export time and selects the highest one your browser accepts. Most recent M-series Macs and current Intel / AMD chips encode 4K @ 30 fps comfortably.

Can I make vertical MIDI videos for TikTok, Reels, or Shorts? Yes. Pick the vertical 9:16 preset for a 1080 × 1920 MP4 ready for short-form feeds.

What file size should I expect? At the default 8 Mbps video bitrate, expect roughly 1 MB per second of video — about 180 MB for a 3-minute MP4 at 1080p. The audio track adds ~1.5 MB per minute. 720p exports are typically half the file size; 4K is about four times larger.

Can I use copyrighted MIDI files? midee will open any standard MIDI file. Copyright and platform terms are between you and the rights holders; midee does not filter content.

Does midee work offline? After the first visit, yes. midee is a Progressive Web App — installable on desktop and mobile, with the app shell cached for offline use. The MIDI-to-MP4 pipeline runs entirely client-side, so it does not need a network connection once loaded.

Try it

Open midee in your browser, drag in a .mid file, preview the piano-roll visualization, and export an MP4. Start with 1080p for YouTube and landscape players, or Vertical for Shorts, TikTok, and Reels. The render runs in your tab while you do something else — no upload, no install, no waiting on a server queue.

If you also want to see midee compared against other MIDI tools, read the Synthesia alternative writeup or browse the best MIDI visualizers shortlist. To go deeper on piano-roll video specifically, see the piano-roll video maker page.