示例#1
0
        /// <summary>
        /// Exports a MIDI file
        /// </summary>
        /// <param name="filename">Filename to export to</param>
        /// <param name="events">Events to export</param>
        public static void Export(string filename, MidiEventCollection events)
        {
            if (events.MidiFileType == 0 && events.Tracks > 1)
            {
                throw new ArgumentException("Can't export more than one track to a type 0 file");
            }
            using (var writer = new BinaryWriter(File.Create(filename)))
            {
                writer.Write(Encoding.UTF8.GetBytes("MThd"));
                writer.Write(SwapUInt32((uint)6));                 // chunk size
                writer.Write(SwapUInt16((ushort)events.MidiFileType));
                writer.Write(SwapUInt16((ushort)events.Tracks));
                writer.Write(SwapUInt16((ushort)events.DeltaTicksPerQuarterNote));

                for (int track = 0; track < events.Tracks; track++)
                {
                    IList <MidiEvent> eventList = events[track];

                    writer.Write(Encoding.UTF8.GetBytes("MTrk"));
                    long trackSizePosition = writer.BaseStream.Position;
                    writer.Write(SwapUInt32((uint)0));

                    long absoluteTime = events.StartAbsoluteTime;

                    // use a stable sort to preserve ordering of MIDI events whose
                    // absolute times are the same
                    MergeSort.Sort(eventList, new MidiEventComparer());
                    if (eventList.Count > 0)
                    {
                        System.Diagnostics.Debug.Assert(MidiEvent.IsEndTrack(eventList[eventList.Count - 1]), "Exporting a track with a missing end track");
                    }
                    foreach (MidiEvent midiEvent in eventList)
                    {
                        midiEvent.Export(ref absoluteTime, writer);
                    }

                    uint trackChunkLength = (uint)(writer.BaseStream.Position - trackSizePosition) - 4;
                    writer.BaseStream.Position = trackSizePosition;
                    writer.Write(SwapUInt32(trackChunkLength));
                    writer.BaseStream.Position += trackChunkLength;
                }
            }
        }
示例#2
0
        /// <summary>
        /// Opens a MIDI file for reading
        /// </summary>
        /// <param name="filename">Name of MIDI file</param>
        /// <param name="strictChecking">If true will error on non-paired note events</param>
        public MidiFile(string filename, bool strictChecking)
        {
            this.strictChecking = strictChecking;

            var br = new BinaryReader(File.OpenRead(filename));

            using (br)
            {
                string chunkHeader = Encoding.UTF8.GetString(br.ReadBytes(4));
                if (chunkHeader != "MThd")
                {
                    throw new FormatException("Not a MIDI file - header chunk missing");
                }
                uint chunkSize = SwapUInt32(br.ReadUInt32());

                if (chunkSize != 6)
                {
                    throw new FormatException("Unexpected header chunk length");
                }
                // 0 = single track, 1 = multi-track synchronous, 2 = multi-track asynchronous
                fileFormat = SwapUInt16(br.ReadUInt16());
                int tracks = SwapUInt16(br.ReadUInt16());
                deltaTicksPerQuarterNote = SwapUInt16(br.ReadUInt16());

                events = new MidiEventCollection((fileFormat == 0)?0:1, deltaTicksPerQuarterNote);
                for (int n = 0; n < tracks; n++)
                {
                    events.AddTrack();
                }

                long absoluteTime = 0;

                for (int track = 0; track < tracks; track++)
                {
                    if (fileFormat == 1)
                    {
                        absoluteTime = 0;
                    }
                    chunkHeader = Encoding.UTF8.GetString(br.ReadBytes(4));
                    if (chunkHeader != "MTrk")
                    {
                        throw new FormatException("Invalid chunk header");
                    }
                    chunkSize = SwapUInt32(br.ReadUInt32());

                    long      startPos           = br.BaseStream.Position;
                    MidiEvent me                 = null;
                    var       outstandingNoteOns = new List <NoteOnEvent>();
                    while (br.BaseStream.Position < startPos + chunkSize)
                    {
                        me              = MidiEvent.ReadNextEvent(br, me);
                        absoluteTime   += me.DeltaTime;
                        me.AbsoluteTime = absoluteTime;
                        events[track].Add(me);
                        if (me.CommandCode == MidiCommandCode.NoteOn)
                        {
                            NoteEvent ne = (NoteEvent)me;
                            if (ne.Velocity > 0)
                            {
                                outstandingNoteOns.Add((NoteOnEvent)ne);
                            }
                            else
                            {
                                // don't remove the note offs, even though
                                // they are annoying
                                // events[track].Remove(me);
                                FindNoteOn(ne, outstandingNoteOns);
                            }
                        }
                        else if (me.CommandCode == MidiCommandCode.NoteOff)
                        {
                            FindNoteOn((NoteEvent)me, outstandingNoteOns);
                        }
                        else if (me.CommandCode == MidiCommandCode.MetaEvent)
                        {
                            MetaEvent metaEvent = (MetaEvent)me;
                            if (metaEvent.MetaEventType == MetaEventType.EndTrack)
                            {
                                //break;
                                // some dodgy MIDI files have an event after end track
                                if (strictChecking)
                                {
                                    if (br.BaseStream.Position < startPos + chunkSize)
                                    {
                                        throw new FormatException(String.Format("End Track event was not the last MIDI event on track {0}", track));
                                    }
                                }
                            }
                        }
                    }
                    if (outstandingNoteOns.Count > 0)
                    {
                        if (strictChecking)
                        {
                            throw new FormatException(String.Format("Note ons without note offs {0} (file format {1})", outstandingNoteOns.Count, fileFormat));
                        }
                    }
                    if (br.BaseStream.Position != startPos + chunkSize)
                    {
                        throw new FormatException(String.Format("Read too far {0}+{1}!={2}", chunkSize, startPos, br.BaseStream.Position));
                    }
                }
            }
        }