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https://github.com/mortenson/midi-tape

Tape mode style recording for external MIDI devices.
https://github.com/mortenson/midi-tape

external hardware midi webmidi

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Tape mode style recording for external MIDI devices.

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README 

        
# midi-tape



A tape mode style recorder for external MIDI devices, created using Web MIDI.



I made this as an alternative to using a DAW, for situations where you want to

control a few external MIDI devices to make quick songs.



## User guide



midi-tape is a 4-track tape mode style recorder that takes input from one MIDI

device (ex: a MIDI keyboard), and outputs that recording to other MIDI devices

and channels.



You can use this to create songs in a more linear, free-form way than with a

traditional DAW or MIDI sequencer.



Web MIDI isn't supported in many browsers, so please use the latest Chrome and

do not switch tabs while recording.



### Controls



All user input is done through the keyboard to make usage with a smaller

external device (ex: remapped numpad) possible.



- `p` - Play/pause

- `P (shift+p)` - Stop

- `r` - Toggle recording

- `R (shift+r)` - Toggle replace recording

- `m` - Toggle metronome

- `m + up/down` - Change beats per minute

- `m + left/right` - Change beats per bar

- `M (shift+m)` - Toggle count-in

- `1-9/0` - Change track

- `1-9/0 + up/down` - Change output device

- `1-9/0 + left/right` - Change output channel

- `1-9/0 + delete` - Delete track

- `i + up/down` - Change input device

- `up/down` - Change track

- `left/right` - Move tape

- `shift + left/right` - Move tape to next/previous bar

- `t` - Add/clear start point

- `y` - Add/clear end point

- `backspace/delete` - Deletes everything between start/end points

- `shift + backspace/delete` - Deletes pitch bends and control changes between

start/end points

- `v` - Pastes the current track's data between start/end points to current

point

- `V (shift+v)` - Pastes all track data between start/end points to current point

- `i + p` - Plays and tells the input device to play. Useful for recording drum

machines

- `u` - Undo (for track deletion, note deletion, recording sessions, and paste)

- `U (shift+u)` - Redo

- `q` - Toggle quantization

- `q + up/down` - Change quantization level

- `q + left/right` - Change quantization strength



If you need more than 10 tracks, use the "o" key instead of the numerical keys:



- `O (shift+o)` - Add a track

- `o + delete` - Delete current track

- `o + up/down` - Change output device

- `o + left/right` - Change output channel

- `o + p` - Play and solo current track



### The timeline



The timeline displays all notes, pitch bends, and control changes for each

track.



Notes in the current track are green, pitch bends are purple, and control

changes are cyan. When recording, the current track's content will turn red.



The start point, if placed, is turquoise, and the end point if placed is

yellow. You can use start/end points to work on loops in your song - when the

end point is reached, the tape will automatically loop back to the start

point. When you're happy with your loop, you can paste it to the next bar(s).

If not you can delete it to start over.



Per the above control guide, you move around the timeline using arrow keys, and

can hold shift to jump from bar to bar. Most of your time with midi-tape will

be spent moving on the timeline, changing start/end points, and changing

tracks.



### Saving/loading



By default the current tape is saved to persistent browser storage often to

prevent data loss between sessions.



To save your work long-term, click the "Save" button at the bottom of the

screen. This will save the tape as JSON, which you can then load back into

midi-tape when needed.



### Using dummy devices



To avoid errors and allow for easier testing of the tool, dummy/fake input and

output devices are provided for you. The "Dummy Synth" uses Tone.js and

supports polyphony and pitch changes. The "Dummy Keyboard" allow you to play

a C major scale using the keys a, s, d, f, g, h, and j. The k and l keys move

the octave up and down.



Note that these are not meant to be useful for real recording scenarios, so

their functionality will always be limited.



### Monitoring and recording audio



Since it can be a bit difficult to monitor the output of your synths while

listening to midi-tape's metronome, you can click "Monitor Audio" and have your

browser's default input played through the default output. This is also useful

for quick jam sessions without opening a DAW or using something like JACK.



While monitoring, you can click "Record Audio", which will lock keyboard

controls, go to the start of the tape, and play it through while recording

everything that's monitored. Once finished, .webm file will be downloaded. I

would have preferred .wav, but the browser APIs for this are pretty limited.



Once downloaded, you can convert the .webm file with a command like:

```

ffmpeg -i ~/Downloads/midi-tape.webm -vn ~/Downloads/midi-tape.mp3

```



### Exporting a MIDI file



If you're finished recording but want to edit some of the MIDI manually, you

can click "Export MIDI" to download your tape as a .mid file.



Note that this is a one-way operation, you cannot import MIDI files as parsing

them accurately given midi-tape's limited feature set could result in data

loss.



### Notes



- Your input device's MIDI channel is ignored, to keep the idea that one track is

one MIDI output device + one channel.

- A MIDI clock is sent to all outputs every quarter note.

- Since it's JavaScript, the BPM is likely always a little off.

- The tape runs at a resolution of 24 PPQ. Higher PPQ values make the tape run

inconsistently.

- Replacing is destructive (just like a real tape) - use it wisely!

- You will have to manage MIDI input delays yourself - for Linux, try

installing a package like Ubuntu's `linux-lowlatency`. For Windows, try using

ASIO4All Driver.



## Development



midi-tape is built using vanilla JavaScript, and is intended to be used in

modern browsers with Web MIDI support (basically latest Chrome).



I built this over a weekend, and would like to maintain it minimally going

forward. Please do not refactor the entire codebase, and instead add small

sensible features if needed.



To start a local dev server, run `npm start`.



To format code, run `npm run prettier`.



To update copies of vendor libraries, run `npm run build-assets`.