The MidiFile class is an interface for reading and writing Standard MIDI files. MIDI file tracks are stored as a list ofobjects, which in turn are lists of The MidiFile class can be considered to be a two-dimensional array of events that are accessible with the  operator. The first dimension is the track index, and the second dimension is the event index for the given track. Thus, midifile would return the 16th event in the third track.
consist of a list of MIDI message bytes along with timing and other variables. For example, the construct midifile would return the MIDI command byte for the 16th message in the third track, and midifile.tick would return the timestamp for the event (either in delta or absolute tick values, see the tick-related functions described further below).
The two main member functions for reading and writing Standard MIDI Files are read and write. The argument to these functions can be either a filename or an input/output stream object. The status function can be called after reading or writing to determine if the action was successful.
Two additional functions, called writeHex and writeBinasc can be used to print ASCII hex codes that determinstically represent a binary Standard MIDI File. The read function will transparently parse either binary MIDI files, or their ASCII representations in one of these two formats.
The MidiFile class contains a list tracks, each stored as a getTrackCount function will report the current number of tracks in a MidiFile object.object. The  operator accesses each list, and the
The tracks in a MidiFile can reversibly be merged into a single event list by calling the joinTracks function. This will cause the getTrackCount function to report that there is one track in the file, and if the file is written in this state, it will be saved as a type-0 MIDI file (from which the multi-track state will not be recoverable). Before tracks are joined, the events in each track must be in correct time sequence, so the sort function may need to be called before joining the tracks.
The hasJoinedTracks and hasSplitTracks functions can be used to detect the current state of the tracks in a MidiFile. By default, a MidiFile will be in the split state.
When a MidiFile is in the joined state, the original track is stored in the track variable of each . The getSplitTrack function returns the track index for when a MidiFile is in the split state.
Here are functions which relate to adding, deleting and merging tracks:
When a MidiFile is in absolute-tick mode (see further below), the tick variable of objects in the MidiFile are the total number of ticks since the start time for the file. In the absolute-tick mode, MidiEvents can be added to tracks in non-sequential order. To re-arrange the events into proper time order (such as before writing the file), use the sortTracks function, which will sort all tracks in the MIDI file, or sortTrack function, which will sort a particular track by its index number.
MidiEvents stored in a MidiFile structure contain two public variables related to time:
- int MidiEvent::tick — Quanta time-units describing durations in Standard MIDI Files.
- double MidiEvent::seconds — Interpreted physical time units in seconds calculated by doTimeInSecondsAnalysis() from .tick data and tempo meta-messages stored in the MidiFile.
Event tick interpretation
Tick values on MidiEvents can be set to two types of states: (1) delta time, which indicate the number of ticks to wait from the last event in the track before performing the current event, and (2) absoute time, where the tick value represents the cumulative tick time since the start of the MidiFile until the performance time of the current event. Standard MIDI Files store tick times as delta ticks, but it is often more useful to manipulate event data with absolute ticks. The absoluteTicks and deltaTicks functions switch the event tick values within the MidiFile between these two modes:
The isDeltaTime and isAbsoluteTime functions can be used to check which mode in which the event ticks are currently given.
Tick values are symbolic time units, such as rhythms in music notation. For example quarter notes do not have a specific duration in seconds until a tempo is applied to the rhythm. Within Standard MIDI Files, there is a field which specifies how many ticks represent a quarter note. This convserion value can be read or set with the following two MidiFile member functions:
Physical time of events
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