MID vs OPUS
A detailed comparison of MIDI Audio and Opus Audio — file size, quality, compatibility, and which format to choose for your workflow.
MIDI Audio
Audio FilesMIDI stores musical performance data (notes, tempo) rather than audio waveforms.
About MID filesOpus Audio
Audio FilesOpus is a versatile, open-source audio codec optimized for both speech and music at very low bitrates. It is the standard for WebRTC voice calls and excels at real-time communication.
About OPUS filesStrengths Comparison
MID Strengths
- Extremely compact — kilobytes for hours of music.
- Editable in every DAW (Logic, Cubase, Ableton, FL Studio, Reaper).
- Universal hardware interface for electronic instruments.
- 40+ years of stability — MIDI 1.0 files from 1983 still play.
- MIDI 2.0 (2020) extends to 32-bit velocity and polyphonic expression.
OPUS Strengths
- Best-in-class quality across the entire bitrate range.
- Royalty-free and patent-free.
- Ultra-low latency — suitable for live voice and music.
- Handles speech and music equally well — no need to switch codecs.
- Mandatory codec in WebRTC, so supported in every browser by design.
Limitations
MID Limitations
- Not audio — playback quality varies wildly by synthesizer.
- Cannot represent vocals, samples, or non-synthesizable sounds.
- Web browsers stopped auto-playing MIDI around 2005.
- Consumer listeners almost never encounter .mid as a delivery format.
OPUS Limitations
- Very low hardware decoder adoption — software-only on most phones.
- Older platforms (legacy Windows apps, old cars) may not play .opus files.
- Container semantics confusing — Opus lives inside Ogg, WebM, or MP4.
- Encoder tooling is less polished than AAC's commercial ecosystem.
Technical Specifications
| Specification | MID | OPUS |
|---|---|---|
| MIME type | audio/midi | audio/opus |
| Extensions | .mid, .midi, .rmi (Microsoft variant) | .opus, .ogg (container) |
| Standard | MIDI 1.0 (1983), Standard MIDI File (SMF) 1.0 | RFC 6716 (2012) |
| Successor | MIDI 2.0 (2020) | — |
| Protocol | Serial MIDI 31.25 kbit/s (legacy hardware) | — |
| Sample rates | — | 8, 12, 16, 24, 48 kHz |
| Latency | — | 5-60 ms (configurable) |
Typical File Sizes
MID
- Pop song (3 min) 10-50 KB
- Full game soundtrack (Doom-era) 100-800 KB
- Orchestral performance (90 min) 200 KB - 1 MB
OPUS
- Voice call (24 kbps) 180 KB/min
- Podcast (48 kbps) 21 MB/hour
- Music (128 kbps) ~1 MB/min
- High-fidelity music (160 kbps) ~1.2 MB/min
Ready to convert?
Convert between MID and OPUS online, free, and without installing anything. Encrypted upload, automatic deletion after 2 hours.
Frequently Asked Questions
MID (MIDI Audio) is an audio file format used to store sound recordings — music, voice, podcasts, sound effects. The format defines how the audio samples are compressed (or stored raw), what bitrates are supported, and how metadata such as title, artist, album, and cover art is embedded. It is part of the audio files family.
OPUS (Opus Audio) is an audio file format used to store sound recordings — music, voice, podcasts, sound effects. The format defines how the audio samples are compressed (or stored raw), what bitrates are supported, and how metadata such as title, artist, album, and cover art is embedded. It is part of the audio files family.
VLC, foobar2000, and the default media players on Windows and macOS handle MID natively. On mobile, iOS Music and Android media apps vary in their support — popular formats work everywhere; niche ones may need a dedicated app. If playback fails on a device, converting to MP3 or AAC usually solves it.
VLC, foobar2000, and the default media players on Windows and macOS handle OPUS natively. On mobile, iOS Music and Android media apps vary in their support — popular formats work everywhere; niche ones may need a dedicated app. If playback fails on a device, converting to MP3 or AAC usually solves it.
Upload the MID to KaijuConverter and pick MP3, WAV, FLAC, AAC, OGG, or any other target. Our FFmpeg pipeline decodes the audio and re-encodes to the target format at sensible default bitrates (VBR ~190 kbps for music, 96 kbps for speech). Metadata and cover art travel with the audio where both formats support them.
MID can be lossy or lossless depending on the specific variant. Lossy variants (smaller files) discard some audio detail during compression in ways tuned to be inaudible; lossless variants preserve every sample exactly but produce larger files. For distribution, lossy at high bitrate is standard; for archival, lossless wins.