Convert MIDI to 3GP — Free Online Converter

MIDI (.midi) is the full-extension variant of the Standard MIDI File format, widely used on Linux workstations, certain DAWs like LMMS and Ardour, and in educational music software. The .midi extension is functionally identical to .mid — both store SMF Type 0 (single track) or Type 1 (multi-track) performance data including note events, tempo changes, time signatures, and General MIDI program assignments. The longer extension simply reflects platform naming conventions rather than any structural difference.

3GP is a mobile multimedia container standardized by the 3rd Generation Partnership Project for cellular devices. Converting MIDI to 3GP involves synthesizing the MIDI score into an audio waveform using a SoundFont engine, then encoding that waveform into the 3GP container with a mobile-appropriate codec. This is particularly useful for karaoke and music education applications where MIDI content needs to reach students or performers on mobile devices.

Karaoke systems and music theory applications frequently distribute compositions as .midi files because the format allows real-time transposition, tempo adjustment, and instrument muting. However, sharing these compositions with participants who use basic smartphones requires rendering to a universally playable format. 3GP ensures the audio reaches every mobile user regardless of their device's MIDI synthesis capabilities.

Music educators distributing practice tracks or ear training exercises as MIDI can convert to 3GP for instant mobile playback. Students hear a consistent rendering rather than the unpredictable results of whatever synthesizer their phone provides — or more commonly, no playback at all on devices that lack MIDI support entirely.

The conversion pipeline first parses the .midi file's SMF header to determine format type and timing resolution (pulses per quarter note). FFmpeg's MIDI decoder dispatches events to a FluidSynth-compatible engine loaded with a General MIDI SoundFont. The engine processes note-on/off events with velocity mapping, applies program changes to select instrument patches from the GM1 sound set (128 melodic + 47 percussion), and renders control change messages (CC7 volume, CC10 pan, CC64 sustain). The resulting stereo PCM is downmixed and encoded as AAC-LC or AMR-NB within a 3GP container conforming to 3GPP TS 26.244.