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//! Basic abstractions for MIDI Channel Voice / Channel Mode messages. //! //! References: //! - [MIDI messages](https://www.midi.org/specifications-old/item/table-1-summary-of-midi-message) use std::convert::{TryFrom, TryInto}; use crate::{ key::PianoKey, pitch::{Pitched, Ratio}, tuner::ChannelTuner, tuning::KeyboardMapping, }; /// Status bits for "Note Off event". pub const NOTE_OFF: u8 = 0b1000; /// Status bits for "Note On event". pub const NOTE_ON: u8 = 0b1001; /// Status bits for "Polyphonic Key Pressure (Aftertouch)". pub const POLYPHONIC_KEY_PRESSURE: u8 = 0b1010; /// Status bits for "Control Change". pub const CONTROL_CHANGE: u8 = 0b1011; /// Status bits for "Program Change". pub const PROGRAM_CHANGE: u8 = 0b1100; /// Status bits for "Channel Pressure (After-touch)". pub const CHANNEL_PRESSURE: u8 = 0b1101; /// Status bits for "Channel Pressure (After-touch)". pub const PITCH_BEND_CHANGE: u8 = 0b1110; /// A type-safe representation of MIDI messages that aren't System Common messages. #[derive(Copy, Clone, Debug, Eq, PartialEq)] pub struct ChannelMessage { channel: u8, message_type: ChannelMessageType, } impl ChannelMessage { /// Parses a MIDI message. /// /// When no valid Channel Voice or Channel Mode message is provided [`None`] is returned. /// /// # Examples /// ``` /// # use tune::midi::ChannelMessage; /// # use tune::midi::ChannelMessageType; /// let message = ChannelMessage::from_raw_message(&[0b1001_1000, 77, 88]).unwrap(); /// assert_eq!(message.channel(), 8); /// assert_eq!( /// message.message_type(), /// ChannelMessageType::NoteOn { /// key: 77, /// velocity: 88 /// } /// ); /// /// let invalid_message = [1, 2, 3]; /// assert_eq!(ChannelMessage::from_raw_message(&invalid_message), None); /// ``` pub fn from_raw_message(message: &[u8]) -> Option<ChannelMessage> { let status_byte = *message.get(0)?; let channel = status_byte & 0b0000_1111; let action = status_byte >> 4; let message_type = match action { NOTE_OFF => ChannelMessageType::NoteOff { key: *message.get(1)?, velocity: *message.get(2)?, }, NOTE_ON => ChannelMessageType::NoteOn { key: *message.get(1)?, velocity: *message.get(2)?, }, POLYPHONIC_KEY_PRESSURE => ChannelMessageType::PolyphonicKeyPressure { key: *message.get(1)?, pressure: *message.get(2)?, }, CONTROL_CHANGE => ChannelMessageType::ControlChange { controller: *message.get(1)?, value: *message.get(2)?, }, PROGRAM_CHANGE => ChannelMessageType::ProgramChange { program: *message.get(1)?, }, CHANNEL_PRESSURE => ChannelMessageType::ChannelPressure { pressure: *message.get(1)?, }, PITCH_BEND_CHANGE => ChannelMessageType::PitchBendChange { value: u16::from(*message.get(1)?) + u16::from(*message.get(2)?) * 128, }, _ => return None, }; Some(ChannelMessage { channel, message_type, }) } /// Returns the byte representation of a MIDI message. /// /// # Examples /// /// ``` /// # use tune::midi::ChannelMessageType; /// let message = ChannelMessageType::NoteOn { /// key: 77, /// velocity: 88 /// } /// .in_channel(7) /// .unwrap(); /// /// assert_eq!(message.to_raw_message(), [0b1001_0111, 77, 88]); /// ``` pub fn to_raw_message(&self) -> [u8; 3] { match self.message_type { ChannelMessageType::NoteOff { key, velocity } => { channel_message(NOTE_OFF, self.channel, key, velocity) } ChannelMessageType::NoteOn { key, velocity } => { channel_message(NOTE_ON, self.channel, key, velocity) } ChannelMessageType::PolyphonicKeyPressure { key, pressure } => { channel_message(POLYPHONIC_KEY_PRESSURE, self.channel, key, pressure) } ChannelMessageType::ControlChange { controller, value } => { channel_message(CONTROL_CHANGE, self.channel, controller, value) } ChannelMessageType::ProgramChange { program } => { channel_message(PROGRAM_CHANGE, self.channel, program, 0) } ChannelMessageType::ChannelPressure { pressure } => { channel_message(CHANNEL_PRESSURE, self.channel, pressure, 0) } ChannelMessageType::PitchBendChange { value } => channel_message( PITCH_BEND_CHANGE, self.channel, (value % 128) as u8, (value / 128) as u8, ), } } /// Returns the channel of a MIDI message. /// /// # Examples /// /// ``` /// # use tune::midi::ChannelMessage; /// # use tune::midi::ChannelMessageType; /// let message = ChannelMessage::from_raw_message(&[0b1001_1000, 77, 88]).unwrap(); /// assert_eq!(message.channel(), 8); /// ``` pub fn channel(&self) -> u8 { self.channel } /// Returns the channel-agnostic part of a MIDI message. /// /// # Examples /// /// ``` /// # use tune::midi::ChannelMessage; /// # use tune::midi::ChannelMessageType; /// let message = ChannelMessage::from_raw_message(&[0b1001_1000, 77, 88]).unwrap(); /// assert!(matches!(message.message_type(), ChannelMessageType::NoteOn { .. })); /// ``` pub fn message_type(&self) -> ChannelMessageType { self.message_type } /// Applies a tuning transformation to a MIDI message. /// /// This operation only succeeds for polyphonic messages whose transformed note is in the allowed MIDI range [0..128). /// If the transformation is successful the deviation from the accurate transformed note is reported. /// /// # Examples /// /// ``` /// # use assert_approx_eq::assert_approx_eq; /// # use tune::midi::ChannelMessageType; /// # use tune::midi::TransformResult; /// # use tune::note::Note; /// # use tune::scala::KbmRoot; /// # use tune::scala::Scl; /// let tuning = ( /// Scl::builder().push_cents(120.0).build().unwrap(), /// KbmRoot::from(Note::from_midi_number(62)).to_kbm(), /// ); /// /// // Usually, polyphonic messages are transformed /// /// let in_range = ChannelMessageType::NoteOn { key: 100, velocity: 88 } /// .in_channel(8) /// .unwrap(); /// /// match in_range.transform(&tuning) { /// TransformResult::Transformed { message, note, deviation } => { /// assert_eq!(message.channel(), 8); /// assert_eq!( /// message.message_type(), /// ChannelMessageType::NoteOn { key: 108, velocity: 88 } /// ); /// assert_eq!(note, 108); /// assert_approx_eq!(deviation.as_cents(), -40.0); /// }, /// _ => unreachable!(), /// } /// /// // When the transformed note is out of range messages are not transformed /// /// let out_of_range = ChannelMessageType::NoteOn { key: 120, velocity: 88 } /// .in_channel(8) /// .unwrap(); /// /// assert!(matches!(out_of_range.transform(&tuning), TransformResult::NoteOutOfRange)); /// /// // Monophonic messages are never transformed /// /// let not_transformed = ChannelMessageType::ProgramChange { program: 42 } /// .in_channel(8) /// .unwrap(); /// /// assert!(matches!(not_transformed.transform(&tuning), TransformResult::NotKeyBased)); /// ``` pub fn transform(&self, tuning: impl KeyboardMapping<PianoKey>) -> TransformResult { let mut cloned = *self; match cloned.message_type.get_key_mut() { Some(key) => { let piano_key = PianoKey::from_midi_number(*key); let approximation = tuning.maybe_pitch_of(piano_key).and_then(|pitch| { let approx = pitch.find_in_tuning(()); approx .approx_value .checked_midi_number() .map(|midi_number| (midi_number, approx.deviation)) }); match approximation { Some((note, deviation)) => { *key = note; TransformResult::Transformed { message: cloned, note, deviation, } } None => TransformResult::NoteOutOfRange, } } None => TransformResult::NotKeyBased, } } } fn channel_message(prefix: u8, channel: u8, payload1: u8, payload2: u8) -> [u8; 3] { [prefix << 4 | channel, payload1, payload2] } /// The result of a tuning transformation on a MIDI message. #[derive(Copy, Clone, Debug)] pub enum TransformResult { Transformed { message: ChannelMessage, note: u8, deviation: Ratio, }, NotKeyBased, NoteOutOfRange, } /// A parsed representation of the channel-agnostic part of a MIDI message. #[derive(Copy, Clone, Debug, Eq, PartialEq)] pub enum ChannelMessageType { NoteOff { key: u8, velocity: u8 }, NoteOn { key: u8, velocity: u8 }, PolyphonicKeyPressure { key: u8, pressure: u8 }, ControlChange { controller: u8, value: u8 }, ProgramChange { program: u8 }, ChannelPressure { pressure: u8 }, PitchBendChange { value: u16 }, } impl ChannelMessageType { /// Creates a new [`ChannelMessage`] from `self` with the given `channel`. /// /// [`None`] is returned if the channel value is outside the range [0..16). /// /// # Examples /// /// ``` /// # use tune::midi::ChannelMessageType; /// let message_type = ChannelMessageType::NoteOn { /// key: 77, /// velocity: 88 /// }; /// let message = message_type.in_channel(15).unwrap(); /// /// assert_eq!(message.channel(), 15); /// assert_eq!(message.message_type(), message_type); /// /// let channel_out_of_range = message_type.in_channel(16); /// assert!(channel_out_of_range.is_none()); /// ``` pub fn in_channel(self, channel: u8) -> Option<ChannelMessage> { match channel < 16 { true => Some(ChannelMessage { channel, message_type: self, }), false => None, } } /// Distributes the given [`ChannelMessageType`] to multiple channels depending on the state of the provided [`ChannelTuner`]. /// /// The parameter `channel_offset` specifies the amount by which the channel number returned by `tuner` will be raised. /// Messages that cannot be mapped to a valid MIDI message will be discarded. /// /// # Examples /// ``` /// # use tune::key::PianoKey; /// # use tune::midi::ChannelMessageType; /// # use tune::note::Note; /// # use tune::scala::KbmRoot; /// # use tune::scala::Scl; /// # use tune::tuner::ChannelTuner; /// let mut tuning = ( /// Scl::builder().push_cents(25.0).build().unwrap(), /// KbmRoot::from(Note::from_midi_number(62)).to_kbm(), /// ); /// /// let (tuner, _) = ChannelTuner::apply_full_keyboard_tuning( /// &tuning, /// (0..128).map(PianoKey::from_midi_number), /// ); /// /// // Usually, polyponic messages are distributed /// /// let in_range = ChannelMessageType::NoteOn { /// key: 91, /// velocity: 88, /// }; /// /// let distributed = in_range.distribute(&tuner, 4); /// assert_eq!(distributed.len(), 1); /// assert_eq!( /// distributed[0].message_type(), /// ChannelMessageType::NoteOn { /// key: 69, /// velocity: 88, /// } /// ); /// assert_eq!(distributed[0].channel(), 6); /// /// // When mapped channel is out of range messages are discarded /// /// assert!(in_range.distribute(&tuner, 14).is_empty()); /// /// // When transformed note is out of range messages are discarded /// /// let mut macrotuning = ( /// Scl::builder().push_cents(120.0).build().unwrap(), /// KbmRoot::from(Note::from_midi_number(62)).to_kbm(), /// ); /// /// let (macrotuner, _) = ChannelTuner::apply_full_keyboard_tuning( /// ¯otuning, /// (0..128).map(PianoKey::from_midi_number), /// ); /// /// let out_of_range = ChannelMessageType::NoteOn { /// key: 120, /// velocity: 88, /// }; /// /// assert!(out_of_range.distribute(¯otuner, 4).is_empty()); /// /// // Monophonic messages are distributed to multiple channels /// /// let monophonic = ChannelMessageType::ProgramChange { program: 42 }; /// /// let distributed = monophonic.distribute(&tuner, 4); /// assert_eq!(distributed.len(), 4); /// for (index, channel) in (0..4).zip(4..8) { /// assert_eq!( /// distributed[index].message_type(), /// ChannelMessageType::ProgramChange { program: 42 } /// ); /// assert_eq!(distributed[index].channel(), channel); /// } /// /// // When mapped channel is out of range messages are discarded /// /// let distributed = monophonic.distribute(&tuner, 14); /// assert_eq!(distributed.len(), 2); /// for (index, channel) in (0..2).zip(14..16) { /// assert_eq!( /// distributed[index].message_type(), /// ChannelMessageType::ProgramChange { program: 42 } /// ); /// assert_eq!(distributed[index].channel(), channel); /// } /// ``` pub fn distribute( &self, tuner: &ChannelTuner<PianoKey>, channel_offset: u8, ) -> Vec<ChannelMessage> { let mut cloned = *self; match cloned.get_key_mut() { Some(key) => { if let Some((channel, note)) = tuner.get_channel_and_note_for_key(PianoKey::from_midi_number(*key)) { if let (Ok(channel), Some(note)) = ( u8::try_from(channel + usize::from(channel_offset)), note.checked_midi_number(), ) { if channel < 16 { *key = note; return vec![ChannelMessage { channel, message_type: cloned, }]; } } } vec![] } None => (channel_offset ..(usize::from(channel_offset) + tuner.num_channels()) .min(16) .try_into() .unwrap()) .map(|channel| ChannelMessage { channel, message_type: *self, }) .collect(), } } fn get_key_mut(&mut self) -> Option<&mut u8> { match self { ChannelMessageType::NoteOff { key, .. } => Some(key), ChannelMessageType::NoteOn { key, .. } => Some(key), ChannelMessageType::PolyphonicKeyPressure { key, .. } => Some(key), _ => None, } } } #[cfg(test)] mod tests { use super::*; #[test] fn parse_note_off() { let message = ChannelMessage::from_raw_message(&[0b1000_0111, 88, 99]).unwrap(); assert_eq!( message, ChannelMessage { channel: 7, message_type: ChannelMessageType::NoteOff { key: 88, velocity: 99 } } ); } #[test] fn parse_note_on() { let message = ChannelMessage::from_raw_message(&[0b1001_1000, 77, 88]).unwrap(); assert_eq!( message, ChannelMessage { channel: 8, message_type: ChannelMessageType::NoteOn { key: 77, velocity: 88 } } ); } #[test] fn parse_polyphonic_key_pressure() { let message = ChannelMessage::from_raw_message(&[0b1010_1001, 66, 77]).unwrap(); assert_eq!( message, ChannelMessage { channel: 9, message_type: ChannelMessageType::PolyphonicKeyPressure { key: 66, pressure: 77 } } ); } #[test] fn parse_control_change() { let message = ChannelMessage::from_raw_message(&[0b1011_1010, 55, 66]).unwrap(); assert_eq!( message, ChannelMessage { channel: 10, message_type: ChannelMessageType::ControlChange { controller: 55, value: 66 } } ); } #[test] fn parse_program_change() { let message = ChannelMessage::from_raw_message(&[0b1100_1011, 44]).unwrap(); assert_eq!( message, ChannelMessage { channel: 11, message_type: ChannelMessageType::ProgramChange { program: 44 } } ); } #[test] fn parse_channel_pressure() { let message = ChannelMessage::from_raw_message(&[0b1101_1100, 33]).unwrap(); assert_eq!( message, ChannelMessage { channel: 12, message_type: ChannelMessageType::ChannelPressure { pressure: 33 } } ); } #[test] fn parse_pitch_bend_change() { let message = ChannelMessage::from_raw_message(&[0b1110_1101, 22, 33]).unwrap(); assert_eq!( message, ChannelMessage { channel: 13, message_type: ChannelMessageType::PitchBendChange { value: 4246 } } ); } #[test] fn serialize_note_off() { let message = ChannelMessage { channel: 7, message_type: ChannelMessageType::NoteOff { key: 88, velocity: 99, }, }; assert_eq!(message.to_raw_message(), [0b1000_0111, 88, 99]); } #[test] fn serialize_note_on() { let message = ChannelMessage { channel: 8, message_type: ChannelMessageType::NoteOn { key: 77, velocity: 88, }, }; assert_eq!(message.to_raw_message(), [0b1001_1000, 77, 88]); } #[test] fn serialize_polyphonic_key_pressure() { let message = ChannelMessage { channel: 9, message_type: ChannelMessageType::PolyphonicKeyPressure { key: 66, pressure: 77, }, }; assert_eq!(message.to_raw_message(), [0b1010_1001, 66, 77]); } #[test] fn serialize_control_change() { let message = ChannelMessage { channel: 10, message_type: ChannelMessageType::ControlChange { controller: 55, value: 66, }, }; assert_eq!(message.to_raw_message(), [0b1011_1010, 55, 66]); } #[test] fn serialize_program_change() { let message = ChannelMessage { channel: 11, message_type: ChannelMessageType::ProgramChange { program: 44 }, }; assert_eq!(message.to_raw_message(), [0b1100_1011, 44, 0]); } #[test] fn serialize_channel_pressure() { let message = ChannelMessage { channel: 12, message_type: ChannelMessageType::ChannelPressure { pressure: 33 }, }; assert_eq!(message.to_raw_message(), [0b1101_1100, 33, 0]); } #[test] fn serialize_pitch_bend_change() { let message = ChannelMessage { channel: 13, message_type: ChannelMessageType::PitchBendChange { value: 4246 }, }; assert_eq!(message.to_raw_message(), [0b1110_1101, 22, 33]); } }