Why Opus for rendered MIDI
Opus is the most efficient general-purpose audio codec in wide use. It keeps music clean at 96–128 kbps, where MP3 would start to sound dull. All modern browsers play it, and it is the codec of Discord, WebRTC calls and many web games. When you convert MIDI to Opus, you get a render that is small enough to load quickly on a web page or send in a chat, but still clean.
Typical uses: background music for a website or browser game, sharing a composition draft on a Discord server, or storing many renders of practice files on a phone.
Bitrate guide
| Music | Opus bitrate | Size per minute |
|---|---|---|
| Solo piano, chiptune, simple melody | 64–96 kbps | 0.5–0.7 MB |
| Band or full arrangement | 96–128 kbps | 0.7–1 MB |
| Dense orchestral music | 160 kbps | about 1.2 MB |
The source is a clean synthesizer render, not a lossy file, so Opus can work at its best. This is one of the few conversions where a low bitrate still gives an excellent result.
48 kHz output
The Opus codec always runs at a 48 kHz sample rate. Choose 48 kHz in the settings to render at that rate directly; a 44.1 kHz render is resampled when it is encoded. Players report the file as 48 kHz. That is normal and has no downside.
Compatibility
- Plays well in: Chrome, Firefox, Edge, Android, VLC, Discord, Telegram, most web audio libraries.
- May not play in: older iPhones and Macs, Windows Media Player on older systems, many car stereos.
For those, MIDI to MP3 or MIDI to M4A is the safer option.
About the sound
A General MIDI soundfont gives the instruments their tone; the file provides the notes, tempo, instrument numbers, volume and panning. Preview the result before saving. For looping web game music, trim the fade-out tail at the end with the audio editor so the loop point falls on the beat.