Library facilitates MIDI Access API and MIDI data processing, supporting both MIDI 1.0 and MIDI 2.0 protocols. Features include MIDI message handling, Standard MIDI File manipulation, and MIDI player functionality, with platform-specific implementations and MIDI-CI support.
ktmidi is a Kotlin Multiplatform library for MIDI Access API and MIDI data processing that covers MIDI 1.0 and MIDI 2.0.
It provides various MIDI features, including implementations for MIDI 1.0, Standard MIDI File Format, MIDI 2.0 UMP, MIDI-CI and related specifications.
In ktmidi module:
In ktmidi-ci module (the overall API is unstable and subject to change):
MidiCIDevice class implements MIDI-CI agent models that conforms to MIDI-CI, Common Rules for MIDI-CI Profile Inquiry, and Common Rules for MIDI-CI Property Exchange specifications.Message implements the sturecures for each MIDI-CI message type.CIFactory and CIRetrieval classes.See MIDI-CI design doc for more details.
There are handful of sample project modules:
player-sample is an example console MIDI player for Kotlin/JVM desktop.player-sample-native is almost the same, but for Kotlin/Native desktop.input-sample is an example console MIDI input receiver that dumps the MIDI messages it received, for Kotlin/JVM desktop.ktmidi-ci-tool is a comprehensive MIDI-CI functionality demo that connects to another MIDI-CI device (through a pair of MIDI connections so far).Here is an example code excerpt to set up platform MIDI device access, load an SMF from some file, and play it:
// for some complicated reason we don't have simple "default" MidiAccess API instance
val access = if(File("/dev/snd/seq").exists()) AlsaMidiAccess() else JvmMidiAccess()
val bytes = Files.readAllBytes(Path.of(fileName)).toList()
val music = MidiMusic()
music.read(bytes)
val player = MidiPlayer(music, access)
player.play()
To use ktmidi, add the following lines in the dependencies section in build.gradle(.kts):
dependencies {
implementation "dev.atsushieno:ktmidi:+" // replace + with the actual version
}
The actual artifact might be platform dependent like dev.atsushieno:ktmidi-android:+ or dev.atsushieno:ktmidi-js:+, depending on the project targets.
If you want to bring better user experience on desktop (which @atsushieno recommends because javax.sound.midi on Linux is quite featureless), add ktmidi-jvm-desktop too,
dependencies {
implementation "dev.atsushieno:ktmidi-jvm-desktop:+" // replace + with the actual version
}
... and use LibreMidiAccess for best cross-platform compatibility as well as best MIDI 2.0 support state.
NOTE: if you are building a desktop MIDI library using RtMidiAccess in ktmidi-jvm-desktop, your application needs to add javacpp-platform Gradle plugin:
plugins {
id("org.bytedeco.gradle-javacpp-platform") version "1.5.10"
}
and the following lines for dependencies:
dependencies {
(...)
api(libs.rtmidi.javacpp.platform)
}
The JavaCPP Platform Gradle plugin replaces the reference to *.javacpp.platform library with the actual platform-specific ones. (You should NOT do this in your library build, as it will result in that your library is useful only on the same platform as your building environment(!))
Also note that JavaCPP Platform Gradle plugin has problem that it fails to retrieve its native dependency from Maven package. You are supposed to publish rtmidi-javacpp or libremidi-javacpp (if you resort to it) to mavenLocal. (It is really annoying so we deprecated them.)
ktmidi is released at sonatype and hence available at Maven Central.
For platform MIDI access API, we cover the following APIs:
For dependency resolution reason, ALSA implementation, libremidi implementation, and rtmidi implementation are split from ktmidi-jvm and formed as ktmidi-jvm-desktop.
ktmidi builds for Kotlin/JVM, Kotlin/JS and Kotlin/Native (though I only develop with Kotlin/JVM and Kotlin/JS so far).
The entire API is still subject to change, and it had been actually radically changing when development was most active.
ktmidi supports MIDI 2.0 UMPs, and MIDI-CI if you count it as part of MIDI 2.0.
UMPs It can be sent and received to and from device where the underlying API supports them. MidiAccess supports either MIDI 1.0 or 2.0, sometimes both. MidiPort and MidiPortDetails have midiTransportProtocol property to identify which is supported.
ktmidi assumes there are various other use-cases without those message exchanges e.g. use of UMPs in MIDI 2.0-only messaging in apps or audio plugins (for example, Audio Plugins For Android along with resident-midi-keyboard).
Since you can derive from MidiAccess abstract API, you can create your own MIDI access implementation and don't have to wait for platform native API to support MIDI 2.0.
It would be useful for general MIDI 2.0 software tools such as MIDI 2.0 UMP player. kmdsp aims to achieve it (once MIDI 2.0 devices are available).
Here is a list of MIDI 2.0 extensibility in this API:
atsushieno/kmmk, a virtual MIDI keyboard app, supports "MIDI 2.0 mode" which sends MIDI messages in MIDI 2.0 UMPs. There is also an ongoing experimental project to process MIDI 2.0 UMPs in audio plugins on Android.
atsushieno/kmdsp, a visual MIDI player, has MIDI 2.0 mode as well (unverified and not known to work, we need MIDI 2.0 devices).
atsushieno/compose-audio-controls comes with a keyboard control for Compose Multiplatform, with option ktmidi integration.
MIDI 2.0 June 2023 updates comes with a brand-new MIDI Clip File specification, which calls itself "SMF2". Though it is not a multi-track music file format like SMF. Therefore, we still have our own format. See docs/MIDI2_FORMATS.md for details.
It is implemented as Midi2Music (read() and write()), and mugene-ng makes use of it to generate music files that are based on this format.
It started as the Kotlin port of C# managed-midi library. Also it started with partial copy of fluidsynth-midi-service-j project.
However everything in this project went far beyond them and now we are making it usable for MIDI 2.0.
Some of the MIDI 2.0 related bits are ported from cmidi2 library.
Historically ktmidi-jvm-desktop used to reside in its own repository to avoid complicated dependency resolution, so there would be some outdated information that tells it was isolated from this project/repository.
We use GitHub issues for bug reports etc., and GitHub Discussions boards open to everyone.
For hacking and/or contributing to ktmidi, please have a look at docs/HACKING.md.
There is Application/library showcase discussions thread.
API documentation is published at: https://atsushieno.github.io/ktmidi/
(The documentation can be built using ./gradlew dokkaHtml and it will be generated locally at build/dokka/html.)
There are couple of API/implementation design docs:
You can also find some real-world usage examples of these API components:
MidiAccess/ktmidi is distributed under the MIT license.
jazz-soft/JZZ is included in ktmidi-js package and is distributed under the MIT license.
rtmidi is included in ktmidi-native-ext package and is distributed under the MIT license. (It is also indirectly referenced via rtmidi-jna, which may be a different version.)
midi-ci-tool uses Wavesonics/compose-multiplatform-file-picker which is distributed under the MIT license.
MidiAccess : MIDI access abstraction API like Web MIDI API.
javax.sound.midi API, this API also covers creating virtual ports wherever possible.
ktmidi-jvm-desktop module contains the following extra backends:
AlsaMidiAccess)LibreMidiAccess) via atsushieno/libremidi-panama for Linux, MacOS, and WindowsRtMidiAccess) via atsushieno/rtmidi-javacpp for Linux and MacOS
ktmidi-native-ext module contains RtMidi native backend (RtMidiNativeAccess) for Kotlin-Native. input-sample and player-sample` Multiplatform apps support it.UmpCoreMidiAccess (supports access to MIDI 2.0 and 1.0 devices, only on newer OSes) and TraditionalCoreMidiAccess (supports access to MIDI 1.0 devices).JzzMidiAccess which wraps Jazz-Soft JZZ is included in ktmidi module. It should cover both node.js and web browsers.WebMidiAccess in ktmidi module makes use of Web MIDI API directly. (Node/Deno via wasmWasi is not covered yet.)MidiMusic and Midi2Music : represents Standard MIDI File format structure, with reader and writer. (MIDI 2.0 support only partially based on standard; Midi2Track follows MIDI Clip File specification but there is no multi-track comparable specification to SMF for MIDI 2.0 yet.)
MidiChannelStatus, MidiCC, MidiRpn, MidiMetaType etc. so that you don't have to remember the actual constant numbers.MidiMusic.read() reads and MidiMusic.write() writes to SMF (standard MIDI format) files with MIDI messages, with Midi1TrackMerger, Midi2TrackMerger, Midi1TrackSplitter and Midi2TrackSplitter that help you implement sequential event processing for your own MIDI players, or per-track editors if needed.UmpFactory and UmpRetriever provides various accessors to MIDI 2.0 Ump data class.UmpTranslator covers the standard conversion between MIDI 1.0 and MIDI 2.0 protocols, with a set of extensive options.Midi1Machine and Midi2Machine work as a potential MIDI device internal state machine, which is also to cover MIDI-CI Process Inquiry "MIDI Message Report" feature.MidiPlayer and Midi2Player: provides MIDI player functionality: play/pause/stop and fast-forwarding.
MidiPlayerTimer. You can pass a stub implementation that does not wait, for testing.AndroidMidiAccess: Android MIDI API (in Kotlin)AlsaMidiAccess: ALSA sequencerLibreMidiAccess : libremidi (which covers Windows, Mac, and Linux). Supports both MIDI 1.0 and 2.0 where available.RtMidiAccess: rtmidi (which covers Windows, Mac, Linux, and iOS, but iOS is in general excluded in JVM solution. Note that rtmidi-javacpp contains prebuilt binaries only for those x86_64 desktop targets. For other platforms, you are supposed to set up rtmidi 5.0.x locally..)RtMidiNativeAccess: rtmidi access for Kotln/Native implementation. Note tha there is a static linking issue to be resolved.UmpCoreMidiAccess: Apple CoreMIDI API on Kotlin/Native. MIDI 2.0 or 1.0, but only on newer OSes.TraditionalCoreMidiAccess: Apple CoreMIDI API on Kotlin/Native. MIDI 1.0 only.JvmMidiAccess: javax.sound.midi API (has limited feature set by Java API nature).WebMidiAccess : Web MIDI API for Kotlin/Wasm target (browser only).JzzMidiAccess : Web MIDI API for Kotlin/JS target (browser and nodejs, experimental, untested).MidiInput and MidiOutput now has midiProtocol property which can be get and/or set. When MidiCIProtocolType.MIDI2 is specified, then the I/O object is supposed to process UMPs (Universal MIDI Packets).Midi2Music is a feature parity with MidiMusic, but all the messages are stored as UMPs. Since ktmidi 0.5.0 we support the Delta Clockstamps as well as DCTPQ, as well as Flex Data messages that correspond to SMF meta events (though not fully, as it is technically impossible). See docs/MIDI2_FORMATS.md for details.Midi2Player is a feature parity with MidiPlayer.UmpFactory class contains a bunch of utility functions that are used to construct UMP integer values.dev.atsushieno.ktmidi.ci package contains a bunch of utility functions that are used to construct MIDI-CI system exclusive packets.MidiOutputSurfaced from shared tags and platforms — no rankings paid for.