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CLAP Audio Plugin API
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commit 0fc394f0a764d42ec7d3edf6d3c17153db4ebf3b
parent fa2beac3d9b4242d01741635c4572b015251cd3f
Author: Paul Walker <paul@pwjw.com>
Date:   Mon, 15 Jan 2024 07:30:12 -0500

Expand some note and note expression doc

The comments in #380 showed some places where our note and
note expression doc had too much implicit knowledge. Try to
address that with a few short paragraphs explainign the protocol

Diffstat:
Minclude/clap/events.h | 25++++++++++++++++++++-----
1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/include/clap/events.h b/include/clap/events.h @@ -151,13 +151,28 @@ enum { typedef struct clap_event_note { clap_event_header_t header; - int32_t note_id; // -1 if unspecified, otherwise >=0 - int16_t port_index; - int16_t channel; // 0..15 - int16_t key; // 0..127 + int32_t note_id; // host provided note id, -1 if unspecified or wildcard + int16_t port_index; // Port index from ext/note-ports; -1 for wildcard + int16_t channel; // 0..15, same as MIDI1 Channel Number, -1 for wildcard + int16_t key; // 0..127, same as MIDI1 Key Number (60==Middle C), -1 for wildcard double velocity; // 0..1 } clap_event_note_t; +// Note Expressions are well named modifications of a voice targeted to +// voices using the same wildcard rules described above. Note Expressions are delivered +// as sample accurate events and should be applied at the sample when received. +// +// Note expressions are a statement of value, not cumulative. A PAN event of 0 followed by 1 +// followed by 0.5 would pan hard left, hard right, and center. They are intended as +// an offset from the non-note-expression voice default. A voice which had a volume of +// -20db absent note expressions which received a +4db note expression would move the +// voice to -16db. +// +// A plugin which receives a note expression at the same sample as a NOTE_ON event +// should apply that expression to all generated samples. A plugin which receives +// a note expression after a NOTE_ON event should initiate the voice with default +// values and then apply the note expression when received. A plugin may make a choice +// to smooth note expression streams. enum { // with 0 < x <= 4, plain = 20 * log(x) CLAP_NOTE_EXPRESSION_VOLUME = 0, @@ -165,7 +180,7 @@ enum { // pan, 0 left, 0.5 center, 1 right CLAP_NOTE_EXPRESSION_PAN = 1, - // relative tuning in semitone, from -120 to +120 + // relative tuning in semitone, from -120 to +120, in equal temperament CLAP_NOTE_EXPRESSION_TUNING = 2, // 0..1