Extracting note onset from MIDI

I need to extract musical features (note details->pitch, duration, rhythm, loudness, note start time) from a polyphonic (having 2 scores for treble and bass - bass may also have chords) MIDI file. I'm using the jMusic API to extract these details from a MIDI file. My approach is to go through each score, into parts, then phrases and finally notes and extract the details.

With my approach, it's reading all the treble notes first and then the bass notes - but chords are not captured (i.e. only a single note of the chord is taken), and I cannot identify from which point onwards are the bass notes. So what I tried was to get the note onsets (i.e. the start time of note being played) - since the starting time of both the treble and bass notes at the start of the piece should be same - But I cannot extract the note onset using jMusic API. For each note it shows 0.0.

Is there any way I can identify the voice (treble or bass) of a note? And also all the notes of a chord? How is the voice or note onset for each note stored in MIDI? Is this different 开发者_高级运维for each MIDI file?

Any insight is greatly appreciated. Thanks in advance

You might want to have a look at this question: Actual note duration from MIDI duration

Where a possible approach to extracting notes from a midi file is discussed.

Consider that a MIDI file can be split on multiple tracks (a "type 1" midifile).

Once you have identified notes, identifying chords can still be tricky. Say you have 3 notes: C, E, G happening "at the same time" (i.e. having been identified as being sound at the same point in a measure). When are they to be considered the C major chord?

• played on the same channel
• played by the same instrument (even if on different channels)
• played on the same channel even if they appear on different tracks

Midifile format is very simple (maybe even too simple!!) I suggest you have a look at its description here: http://duskblue.org/proj/toymidi/midiformat.pdf