Java从MIDI序列获取乐器列表

Question

I need to get the notes, timestamp, and instrument list and all, from general MIDI files.

Almost everything is done, but I also need each instrument corresponding to each track otherwise the notes are useless if I don't know which instrument they belong to.

It seems that this is done by getting the patch list, a patch has the instrument code in a soundbank used by the MIDI sequence.

This seems straight forward, but when I try to use getPatchList() on a Sequence object it returns an empty array.

The problem?: it seems like this was never actually implemented in the java MIDI library (??), at least from what I found:

/**
 * Get an array of patches used in this sequence.
 * 
 * @return an array of patches used in this sequence
 */
public Patch[] getPatchList()
{
  // FIXE: not quite sure how to do this yet. 
  throw new UnsupportedOperationException("Can't get patch list yet");
}

source: javax.sound.midi.Sequence

Aparently the Android developers couldn't figure it out either. Note this is a normal java program, nothing to do with Android:

public Patch[] getPatchList() {
    //FIXME
    /*
     * I don't understand how to works this method, and so
     * I simply return an empty array. 'patches' initializes
     * in the constructor as empty vector 
     */
    Patch[] patch = new Patch[patches.size()];
    patches.toArray(patch);
    return patch;
}

source: javax.sound.midi.Sequence

So is there anything that can be done about this at all?
Is there another way to get the instruments?
Why is this not implemented?
Did no one actually ever need this since 2005?

Answer 1

To get a MIDI device to select an instrument, you would send a Program Change message to it (which would also take into account the current setting of the Bank Select controllers).

To get a list of all patches in a sequence, one goes through the list of all messages, and collects all program numbers (and all bank numbers in effect at that time).

If your implementations are not doing this, you have to do this manually.