private void ParseEvents(int offset, int length, int trackNumber)
{
string s;
int n = offset + length, i, j = 0;
MidiEvent mtrkEvent = null;
MidiMetaEvent metaEvent;
/* A track chunk is a stream of MIDI (MTrk) events. Process each such
* event in this part of the byte array comprising the track chunk.
*/
for (i = offset; i < n; i += mtrkEvent.Size)
{
/* In order to know what kind of event to instantiate, we must read the event's status
* byte, which requires skipping past the delta-time (stored as a variable-length quantity).
*/
for (j = i; j < this.Bytes.Length && (this.Bytes[j] & 0x80) > 0; ++j)
{
if (j - i > 3)
{
s = string.Format("{0} (@ {1} {2})", Properties.Resources.InvalidVLQ, Properties.Resources.Byte, i);
this.AddErrorText(s, trackNumber);
return;
}
}
if (++j >= this.Bytes.Length)
{
break;
}
/* Instantiate an event object of the appropriate type (based on the status byte). */
switch (this.Bytes[j])
{
case 0xFF: mtrkEvent = new MidiMetaEvent(this, i); break;
case 0xF7: mtrkEvent = new MidiSysExEvent(this, i); break;
case 0xF0: mtrkEvent = new MidiSysExEvent(this, i); break;
default: mtrkEvent = new MidiChannelEvent(this, i); break;
}
this.Items.Add(mtrkEvent);
this.SetTotalTime(this.ItemCount - 1);
/* If the event is a MIDI channel message/event that does not use
* running status, use it to set the running status at this byte offset.
*/
if (++j >= this.Bytes.Length)
{
break;
}
MidiChannelEvent channelEvent = mtrkEvent as MidiChannelEvent;
if (channelEvent != null && !channelEvent.RunningStatus)
{
this.SetRunningStatus(i, channelEvent.Status);
}
/* If the event is a meta-event representing a key signature,
* use it to set the key signature at the appropriate time.
*/
if (++j >= this.Bytes.Length)
{
break;
}
metaEvent = MidiFile.ItemToKeySignatureEvent(mtrkEvent);
if (metaEvent != null)
{
this.SetKeySignature(metaEvent);
}
}
/* If we ran out of data, add an error message. */
if (j >= this.Bytes.Length)
{
s = string.Format(Properties.Resources.MismatchFormat, Properties.Resources.Byte, length, i - offset);
this.AddErrorText(s, trackNumber);
}
/* The last event in a track chunk should be an End of Track meta-event. */
metaEvent = mtrkEvent as MidiMetaEvent;
if (metaEvent == null || (metaEvent != null && metaEvent.Type != MidiMetaEvent.EndOfTrackType))
{
this.AddErrorText(Properties.Resources.NoEndOfTrack, trackNumber);
}
}
/// <summary>Initializes a new instance of the MidiMetaEvent class.</summary>
/// <param name="file">MidiFile object representing the MIDI file to which this item belongs.</param>
/// <param name="offset">Offset into the file's byte array at which this item begins.</param>
public MidiMetaEvent(MidiFile file, int offset) : base(file, offset)
{
}
/// <summary>Initializes a new instance of the MidiChannelEvent class.</summary>
/// <param name="file">MidiFile object representing the MIDI file to which this item belongs.</param>
/// <param name="offset">Offset into the file's byte array at which this item begins.</param>
public MidiChannelEvent(MidiFile file, int offset) : base(file, offset)
{
}
/****************
* Constructors *
****************/
#region Public Constructors
/// <summary>Initializes a new instance of the MidiItem class.</summary>
/// <param name="file">MidiFile object representing the MIDI file to which this item belongs.</param>
/// <param name="offset">Offset into the file's byte array at which this item begins.</param>
public MidiItem(MidiFile file, int offset)
{
this._File = file; this.Offset = offset;
}