Audio to MIDI: which formats actually work?
This converter accepts MP3 and WAV files only. Every other container is refused at the file picker. You get a single line of text telling you what happened, and the Convert button stays disabled.
Measured on 6 November 2026 in Chrome 156.0.8078.80 on Windows. One sample per format, all derived from the same four-note WAV. Status strings are the page's own on-screen text, read from the live site.
Supported range
Two formats pass the file picker and proceed to conversion:
| Format | Page status after selecting | Convert button | File information shown |
|---|---|---|---|
| WAV | Ready. Your audio has not left this browser. | Enabled | 4.800 seconds · 211,724 bytes · 1 channel(s) |
| MP3 | Ready. Your audio has not left this browser. | Enabled | 4.824 seconds · 78,201 bytes · 1 channel(s) |
The picker rejects everything else before any audio is read or decoded. There is no silent trimming, no partial acceptance, and no fallback path.
What happens with other formats
We tested seven common containers by dragging each one onto the live page. All seven were refused with the same message:
| Format | Sample size | Page status text | Convert button |
|---|---|---|---|
| FLAC | 49,209 bytes | Choose an MP3 or WAV file. | Disabled |
| OGG | 10,972 bytes | Choose an MP3 or WAV file. | Disabled |
| M4A | 71,237 bytes | Choose an MP3 or WAV file. | Disabled |
| MP4 | 71,257 bytes | Choose an MP3 or WAV file. | Disabled |
| MOV | 71,288 bytes | Choose an MP3 or WAV file. | Disabled |
| WebM | 68,609 bytes | Choose an MP3 or WAV file. | Disabled |
| MKV | 71,335 bytes | Choose an MP3 or WAV file. | Disabled |
All seven samples were encoded from the same four-note source WAV (211,724 bytes) using ffmpeg. The rejection happens at the file-name check in the page code, before the browser attempts to decode audio. No error is thrown, no file is read, and no network request is made.
Convert to WAV first
If your file is in one of the refused formats, convert it to WAV before loading it here. We ran this end to end for all seven formats using ffmpeg, then loaded each resulting WAV into the live converter and pressed Convert.
General command:
ffmpeg -i input.<ext> output.wav| Format | ffmpeg command | WAV size | MIDI bytes | Notes detected | Converted? |
|---|---|---|---|---|---|
| FLAC | ffmpeg -y -i samples/sample-4notes.flac roundtrip/from-flac.wav | 211,758 | 106 | 4 | Yes |
| OGG | ffmpeg -y -i samples/sample-4notes.ogg roundtrip/from-ogg.wav | 211,758 | 124 | 6 | Yes |
| M4A | ffmpeg -y -i samples/sample-4notes.m4a roundtrip/from-m4a.wav | 211,758 | 106 | 4 | Yes |
| MP4 | ffmpeg -y -i samples/sample-4notes.mp4 roundtrip/from-mp4.wav | 211,758 | 106 | 4 | Yes |
| MOV | ffmpeg -y -i samples/sample-4notes.mov roundtrip/from-mov.wav | 211,758 | 106 | 4 | Yes |
| WebM | ffmpeg -y -i samples/sample-4notes.webm roundtrip/from-webm.wav | 460,878 | 106 | 4 | Yes |
| MKV | ffmpeg -y -i samples/sample-4notes.mkv roundtrip/from-mkv.wav | 211,758 | 106 | 4 | Yes |
After transcoding to WAV, every format produced a valid MIDI file with the MThd header. The OGG round trip detected 6 notes instead of 4, and the WebM transcode produced a 48 kHz WAV (460,878 bytes) while the others were 22,050 Hz (211,758 bytes). These are measured differences from this one sample, not guarantees about every file.
Why write this down
We looked at the top nine results for audio to midi on Google. Nine pages, all HTTP 200. None of them states plainly which input formats it accepts or refuses. The angle missing from all nine is not a feature comparison or a speed benchmark; it is the simple fact of what happens when you bring the wrong file. That is what this page records.
Short answers
Does this tool convert FLAC to MIDI?
Not directly. The file picker refuses FLAC with the message Choose an MP3 or WAV file. Convert the FLAC to WAV first using ffmpeg or any audio editor, then load the WAV here.
Can I drag an MP4 or video file in?
No. The picker rejects MP4, MOV, WebM and MKV with the same message. If the file contains audio, extract or convert the audio track to WAV first.
What does the page say when a format is refused?
Choose an MP3 or WAV file. The Convert button stays disabled. No file is read and no network request is made.
Is the WAV conversion guaranteed to work?
We tested one four-note sample per format. All seven produced a MIDI file. Your results will depend on the audio content, codec, and browser build.
Why are only MP3 and WAV accepted?
The file picker checks the file name extension. Only .mp3 and .wav pass. This is a deliberate gate in the page code, not a browser limitation.