private static bool _TryReadChunk(Stream stream, out KeyValuePair <string, byte[]> chunk)
{
chunk = default(KeyValuePair <string, byte[]>);
var buf = new byte[4];
if (4 != stream.Read(buf, 0, 4))
{
return(false);
}
var name = Encoding.ASCII.GetString(buf);
if (4 != stream.Read(buf, 0, 4))
{
throw new EndOfStreamException();
}
var len = BitConverter.ToInt32(buf, 0);
if (BitConverter.IsLittleEndian)
{
len = MidiUtility.Swap(len);
}
buf = new byte[len];
if (len != stream.Read(buf, 0, len))
{
throw new EndOfStreamException();
}
chunk = new KeyValuePair <string, byte[]>(name, buf);
return(true);
}
/// <summary>
/// Reads a MIDI file from the specified stream
/// </summary>
/// <param name="stream">The stream to read from</param>
/// <returns>A MIDI file object representing the MIDI data in the stream</returns>
public static MidiFile ReadFrom(Stream stream)
{
KeyValuePair <string, byte[]> chunk;
if (!_TryReadChunk(stream, out chunk) || "MThd" != chunk.Key || 6 > chunk.Value.Length)
{
throw new InvalidDataException("The stream is not a MIDI file format.");
}
var type = BitConverter.ToInt16(chunk.Value, 0);
var trackCount = BitConverter.ToInt16(chunk.Value, 2);
var timeBase = BitConverter.ToInt16(chunk.Value, 4);
if (BitConverter.IsLittleEndian)
{
type = MidiUtility.Swap(type);
trackCount = MidiUtility.Swap(trackCount);
timeBase = MidiUtility.Swap(timeBase);
}
var result = new MidiFile(type, timeBase);
while (_TryReadChunk(stream, out chunk))
{
if ("MTrk" == chunk.Key)
{
var tstm = new MemoryStream(chunk.Value, false);
var trk = MidiSequence.ReadFrom(tstm);
result.Tracks.Add(trk);
}
}
return(result);
}
/// <summary>
/// Writes the MIDI file to the specified stream
/// </summary>
/// <param name="stream">The stream to write to</param>
public void WriteTo(Stream stream)
{
var fileStream = stream as FileStream;
if (null != fileStream)
{
FilePath = fileStream.Name;
}
try
{
stream.SetLength(0);
}
catch { }
var buf = new byte[4];
buf[0] = (byte)'M'; buf[1] = (byte)'T'; buf[2] = (byte)'h'; buf[3] = (byte)'d';
stream.Write(buf, 0, 4);
var len = 6;
if (BitConverter.IsLittleEndian)
{
len = MidiUtility.Swap(len);
}
stream.Write(BitConverter.GetBytes(len), 0, 4);
var type = Type;
var trackCount = (short)Tracks.Count;
var timeBase = TimeBase;
if (BitConverter.IsLittleEndian)
{
type = MidiUtility.Swap(type);
trackCount = MidiUtility.Swap(trackCount);
timeBase = MidiUtility.Swap(timeBase);
}
stream.Write(BitConverter.GetBytes(type), 0, 2);
stream.Write(BitConverter.GetBytes(trackCount), 0, 2);
stream.Write(BitConverter.GetBytes(timeBase), 0, 2);
foreach (var trk in Tracks)
{
buf[0] = (byte)'M'; buf[1] = (byte)'T'; buf[2] = (byte)'r'; buf[3] = (byte)'k';
stream.Write(buf, 0, 4);
var tstm = new MemoryStream();
trk.WriteTo(tstm);
tstm.Position = 0;
len = (int)tstm.Length;
if (BitConverter.IsLittleEndian)
{
len = MidiUtility.Swap(len);
}
stream.Write(BitConverter.GetBytes(len), 0, 4);
tstm.CopyTo(stream);
tstm.Close();
}
}
/// <summary>
/// Creates a new MIDI channel pitch message
/// </summary>
/// <param name="pitch">The MIDI pressure (0-16383)</param>
/// <param name="channel">The MIDI channel (0-15)</param>
public MidiMessageChannelPitch(short pitch, byte channel) : base(unchecked ((byte)(0xE0 | channel)), BitConverter.IsLittleEndian?MidiUtility.Swap(pitch):pitch)
{
}
