Convert MIDI to MP4 — Free Online Converter

MIDI (.midi) is perhaps the most efficient music representation ever created — a full orchestral symphony encoded in less disk space than a single second of CD audio. The format's power lies in its abstraction: by storing musical decisions (which notes, when, how loud, which instrument) rather than acoustic results, MIDI enables infinite re-interpretation. Every karaoke machine in the world, every synthesizer keyboard, every music education app, and every game with adaptive music relies on MIDI principles.

MP4 (MPEG-4 Part 14) is the universal multimedia container — the format of YouTube, Netflix, iPhone videos, and virtually every piece of media consumed on the internet today. Converting MIDI to MP4 renders the musical score into the world's most universally playable format, making MIDI compositions accessible to the broadest possible audience across every device, browser, and platform in existence.

Content creators on YouTube, TikTok, and Instagram need audio in MP4 format. A MIDI composer who wants to publish synthesized music on these platforms must render to MP4 — the only format that works natively across all major social media platforms, web browsers, smart TVs, and mobile devices without any compatibility issues whatsoever.

Enterprise presentation systems, digital signage networks, and kiosk installations standardize on MP4 as their media format. When businesses need custom music — lobby background audio, on-hold music, branded notification sounds — composing as MIDI and converting to MP4 provides the cheapest production pipeline (no studio recording needed) with maximum deployment compatibility across all enterprise media infrastructure.

FFmpeg decodes the .midi file's event stream, respecting the SMF format type (Type 0 merges all events to one track, Type 1 maintains separate tracks that are mixed during synthesis). The synthesis engine processes the General MIDI instrument map (0: Acoustic Grand Piano through 127: Gunshot) and the GM drum map on channel 10. All MIDI events — note-on/off, control change, program change, pitch bend, channel aftertouch, polyphonic aftertouch — are rendered chronologically through the SoundFont bank. The stereo PCM output is encoded as AAC-LC and muxed into an MP4 container with proper stts (sample-to-time), stsc (sample-to-chunk), stco (chunk offset), and stsz (sample size) table atoms. The moov atom can be placed at the file start (faststart) for progressive web playback.