OneTaskBy Tim King · Updated
MIDI Player
Play .mid Files in Your Browser With a Piano Roll
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How the MIDI Player works
This MIDI player opens a .mid or .midi file and plays it straight away in your browser, no software to install. Every note appears on a piano roll with a moving playhead; click anywhere on it to jump. Slow the song down, transpose it, pick a sound, or mute the drums. With no file loaded, Play runs a short demo tune.
What a MIDI file contains
A MIDI file holds no audio at all. It is a list of instructions: which key goes down, how hard, on which channel, and when it is released, plus tempo changes. Something has to turn those instructions into sound, which is why the same file sounds different on every device. Here a small browser synthesiser does that job, so playback works the same on Windows, Mac, Linux, iPhone and Android.
How the MIDI player reads your file
The player parses Standard MIDI Files of type 0 and type 1, including running status, tempo changes and SMPTE timing. It pairs each note-on with its note-off, converts ticks to seconds through the tempo map, and schedules notes slightly ahead of time so playback stays steady. Channel 10, the General MIDI drum channel, plays as simple kick and hi-hat sounds or can be muted. The file is read locally and is never uploaded.
Practising with it
Drop the speed to 50 or 75% to learn a part, transpose to suit your instrument or voice, and click the piano roll to loop back to a tricky passage. The stats show the file format, track count, note count, length and starting tempo.
FAQ
Why does this sound different from my keyboard?
MIDI only stores notes, not sounds. Your keyboard, phone or DAW uses its own instrument samples, while this player uses a lightweight synthesiser with five simple voices. The notes and timing are the same; only the instrument colour differs.
Does it support General MIDI instruments?
It plays every channel with the sound you choose rather than switching instruments by program change, and treats channel 10 as drums. That keeps the page small and fast; for full General MIDI playback, open the file in a DAW or notation program.
Can I convert the MIDI file to MP3?
Not on this page, which is for listening and inspecting. To go the other way, from a recording to notes, use the audio to MIDI converter. Many DAWs can render a MIDI file to audio with proper instrument sounds if you need an MP3.
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