| Namespace | Windows.Devices.Midi2.Utilities.Sequencing |
|---|---|
| Type Name | MidiSequence |
| Type | WinRT Runtime Class |
| IDL | MidiSequence.idl |
MidiSequence is music on a timeline, ready to be played or drawn. It isn’t tied to any file format, on purpose. A Standard MIDI File gives you one, and so does an app that builds a sequence itself.
A sequence isn’t a collection of message objects. It’s a way to reach the data it stores. Real files can have millions of events, so the busiest parts of a sequence are never handed to your app one item at a time. The smaller parts, which a display needs all of, are normal collections.
| Property | Description |
|---|---|
Format |
The MidiSequenceFormat of the sequence |
TicksPerQuarterNote |
Ticks per quarter note, unless the sequence is timed in SMPTE frames |
UsesSmpteTiming |
True when a tick is a fixed part of a second instead of a musical length. Then tempo doesn’t apply |
TimingMode |
MidiSequenceTimingMode. Whether the ticks above are musical, or are just microseconds. A sequence read from a file is always Musical. Only one built with MidiSequenceBuilder can be Absolute |
DurationMicroseconds |
The total length of the sequence |
LastTick |
The tick of the last event |
| Property | Description |
|---|---|
EventCount |
The total number of events |
NoteCount |
The total number of notes, each with its start and end paired up |
Title |
The title, if the sequence has one |
Copyright |
The copyright text, if the sequence has it |
IsKaraoke |
True when the file says it’s a karaoke file, which changes where its words are stored. It’s worth showing, because it tells your app there are words to display |
LowestNoteNumber |
The lowest note number that’s really played |
HighestNoteNumber |
The highest note number that’s really played |
LongestNoteTicks |
The length of the longest note. It tells you how far back to look to find every note that could still be sounding at a given tick |
UsedChannelMask |
Which channels are used, one bit per channel. Bit zero is channel one |
LowestNoteNumber and HighestNoteNumber let a display fill its height with the music instead of all 128 notes.
Notes are sorted by where they start, so a note that began before a window can still be sounding inside it. LongestNoteTicks is how far back you have to look to catch those.
These are small enough to hand over whole. Each is built once, while reading, and kept.
| Property | Description |
|---|---|
Tracks |
The MidiSequenceTrack collection |
TempoMap |
Every MidiSequenceTempoChange in the sequence |
TimeSignatureMap |
Every MidiSequenceTimeSignature in the sequence |
TextEvents |
Every MidiSequenceTextEvent, including single lyric syllables |
LyricLines |
Syllables put back together into MidiSequenceLyricLine lines |
Both conversions use a map built while reading, so neither one has to go through the whole sequence.
| Method | Description |
|---|---|
ConvertTickToMicroseconds(tick) |
Where a tick falls in time |
ConvertMicrosecondsToTick(microseconds) |
Where a moment in time falls in ticks |
GetBeatsPerMinuteAtTick(tick) |
The tempo at that tick |
GetBarPositionAtTick(tick) |
The MidiSequenceBarPosition at that tick |
These return what’s in effect at a moment, not what happens exactly then. Both return null before the first one in the sequence.
| Method | Description |
|---|---|
GetChordSymbolAtTick(tick) |
The chord symbol in effect, as a text event |
GetLyricLineAtTick(tick) |
The lyric line in effect |
Notes are the large part of a sequence. Ask for a window of time and fill an array you own, so drawing a frame takes one call, not one per note.
| Method | Description |
|---|---|
GetNoteCountInTickRange(startTick, endTick) |
How many notes fall in the window, so you know how big to make your array |
FillNotesInTickRange(startTick, endTick, startIndex, notes) |
Fills your array with MidiSequenceNote values, and returns how many it wrote. It never writes more than your array holds |
FillSoundingNoteCountsAtTick(tick, countsPerTrack) |
Fills your array with how many notes each track is holding at that moment, one entry per track, for a level meter |
If you need notes that began earlier and are still sounding, subtract LongestNoteTicks from the start of your window before you call FillNotesInTickRange. The sequence sorts notes by their start tick, so it can’t find them for you any other way.
Windows MIDI Services is an open source project with all source available on GitHub. We have a great community on Discord as well. Between GitHub and Discord, you should find the information you are looking for.
