JUCE/modules/juce_audio_basics/midi/juce_MidiFile.cpp

/*
  ==============================================================================

   This file is part of the JUCE library.
   Copyright (c) 2013 - Raw Material Software Ltd.

   Permission is granted to use this software under the terms of either:
   a) the GPL v2 (or any later version)
   b) the Affero GPL v3

   Details of these licenses can be found at: www.gnu.org/licenses

   JUCE is distributed in the hope that it will be useful, but WITHOUT ANY
   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
   A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

   ------------------------------------------------------------------------------

   To release a closed-source product which uses JUCE, commercial licenses are
   available: visit www.juce.com for more information.

  ==============================================================================
*/

namespace MidiFileHelpers
{
    static void writeVariableLengthInt (OutputStream& out, unsigned int v)
    {
        unsigned int buffer = v & 0x7f;

        while ((v >>= 7) != 0)
        {
            buffer <<= 8;
            buffer |= ((v & 0x7f) | 0x80);
        }

        for (;;)
        {
            out.writeByte ((char) buffer);

            if (buffer & 0x80)
                buffer >>= 8;
            else
                break;
        }
    }

    static bool parseMidiHeader (const uint8* &data, short& timeFormat, short& fileType, short& numberOfTracks) noexcept
    {
        unsigned int ch = ByteOrder::bigEndianInt (data);
        data += 4;

        if (ch != ByteOrder::bigEndianInt ("MThd"))
        {
            bool ok = false;

            if (ch == ByteOrder::bigEndianInt ("RIFF"))
            {
                for (int i = 0; i < 8; ++i)
                {
                    ch = ByteOrder::bigEndianInt (data);
                    data += 4;

                    if (ch == ByteOrder::bigEndianInt ("MThd"))
                    {
                        ok = true;
                        break;
                    }
                }
            }

            if (! ok)
                return false;
        }

        unsigned int bytesRemaining = ByteOrder::bigEndianInt (data);
        data += 4;
        fileType = (short) ByteOrder::bigEndianShort (data);
        data += 2;
        numberOfTracks = (short) ByteOrder::bigEndianShort (data);
        data += 2;
        timeFormat = (short) ByteOrder::bigEndianShort (data);
        data += 2;
        bytesRemaining -= 6;
        data += bytesRemaining;

        return true;
    }

    static double convertTicksToSeconds (const double time,
                                         const MidiMessageSequence& tempoEvents,
                                         const int timeFormat)
    {
        if (timeFormat < 0)
            return time / (-(timeFormat >> 8) * (timeFormat & 0xff));

        double lastTime = 0.0, correctedTime = 0.0;
        const double tickLen = 1.0 / (timeFormat & 0x7fff);
        double secsPerTick = 0.5 * tickLen;
        const int numEvents = tempoEvents.getNumEvents();

        for (int i = 0; i < numEvents; ++i)
        {
            const MidiMessage& m = tempoEvents.getEventPointer(i)->message;
            const double eventTime = m.getTimeStamp();

            if (eventTime >= time)
                break;

            correctedTime += (eventTime - lastTime) * secsPerTick;
            lastTime = eventTime;

            if (m.isTempoMetaEvent())
                secsPerTick = tickLen * m.getTempoSecondsPerQuarterNote();

            while (i + 1 < numEvents)
            {
                const MidiMessage& m2 = tempoEvents.getEventPointer(i + 1)->message;

                if (m2.getTimeStamp() != eventTime)
                    break;

                if (m2.isTempoMetaEvent())
                    secsPerTick = tickLen * m2.getTempoSecondsPerQuarterNote();

                ++i;
            }
        }

        return correctedTime + (time - lastTime) * secsPerTick;
    }

    // a comparator that puts all the note-offs before note-ons that have the same time
    struct Sorter
    {
        static int compareElements (const MidiMessageSequence::MidiEventHolder* const first,
                                    const MidiMessageSequence::MidiEventHolder* const second) noexcept
        {
            const double diff = (first->message.getTimeStamp() - second->message.getTimeStamp());

            if (diff > 0) return 1;
            if (diff < 0) return -1;
            if (first->message.isNoteOff() && second->message.isNoteOn())   return -1;
            if (first->message.isNoteOn()  && second->message.isNoteOff())  return 1;

            return 0;
        }
    };
}

//==============================================================================
MidiFile::MidiFile()
   : timeFormat ((short) (unsigned short) 0xe728)
{
}

MidiFile::~MidiFile()
{
}

void MidiFile::clear()
{
    tracks.clear();
}

//==============================================================================
int MidiFile::getNumTracks() const noexcept
{
    return tracks.size();
}

const MidiMessageSequence* MidiFile::getTrack (const int index) const noexcept
{
    return tracks [index];
}

void MidiFile::addTrack (const MidiMessageSequence& trackSequence)
{
    tracks.add (new MidiMessageSequence (trackSequence));
}

//==============================================================================
short MidiFile::getTimeFormat() const noexcept
{
    return timeFormat;
}

void MidiFile::setTicksPerQuarterNote (const int ticks) noexcept
{
    timeFormat = (short) ticks;
}

void MidiFile::setSmpteTimeFormat (const int framesPerSecond,
                                   const int subframeResolution) noexcept
{
    timeFormat = (short) (((-framesPerSecond) << 8) | subframeResolution);
}

//==============================================================================
void MidiFile::findAllTempoEvents (MidiMessageSequence& tempoChangeEvents) const
{
    for (int i = tracks.size(); --i >= 0;)
    {
        const int numEvents = tracks.getUnchecked(i)->getNumEvents();

        for (int j = 0; j < numEvents; ++j)
        {
            const MidiMessage& m = tracks.getUnchecked(i)->getEventPointer (j)->message;

            if (m.isTempoMetaEvent())
                tempoChangeEvents.addEvent (m);
        }
    }
}

void MidiFile::findAllTimeSigEvents (MidiMessageSequence& timeSigEvents) const
{
    for (int i = tracks.size(); --i >= 0;)
    {
        const int numEvents = tracks.getUnchecked(i)->getNumEvents();

        for (int j = 0; j < numEvents; ++j)
        {
            const MidiMessage& m = tracks.getUnchecked(i)->getEventPointer (j)->message;

            if (m.isTimeSignatureMetaEvent())
                timeSigEvents.addEvent (m);
        }
    }
}

double MidiFile::getLastTimestamp() const
{
    double t = 0.0;

    for (int i = tracks.size(); --i >= 0;)
        t = jmax (t, tracks.getUnchecked(i)->getEndTime());

    return t;
}

//==============================================================================
bool MidiFile::readFrom (InputStream& sourceStream)
{
    clear();
    MemoryBlock data;

    const int maxSensibleMidiFileSize = 2 * 1024 * 1024;

    // (put a sanity-check on the file size, as midi files are generally small)
    if (sourceStream.readIntoMemoryBlock (data, maxSensibleMidiFileSize))
    {
        size_t size = data.getSize();
        const uint8* d = static_cast <const uint8*> (data.getData());
        short fileType, expectedTracks;

        if (size > 16 && MidiFileHelpers::parseMidiHeader (d, timeFormat, fileType, expectedTracks))
        {
            size -= (size_t) (d - static_cast <const uint8*> (data.getData()));

            int track = 0;

            while (size > 0 && track < expectedTracks)
            {
                const int chunkType = (int) ByteOrder::bigEndianInt (d);
                d += 4;
                const int chunkSize = (int) ByteOrder::bigEndianInt (d);
                d += 4;

                if (chunkSize <= 0)
                    break;

                if (chunkType == (int) ByteOrder::bigEndianInt ("MTrk"))
                    readNextTrack (d, chunkSize);

                size -= (size_t) chunkSize + 8;
                d += chunkSize;
                ++track;
            }

            return true;
        }
    }

    return false;
}

void MidiFile::readNextTrack (const uint8* data, int size)
{
    double time = 0;
    uint8 lastStatusByte = 0;

    MidiMessageSequence result;

    while (size > 0)
    {
        int bytesUsed;
        const int delay = MidiMessage::readVariableLengthVal (data, bytesUsed);
        data += bytesUsed;
        size -= bytesUsed;
        time += delay;

        int messSize = 0;
        const MidiMessage mm (data, size, messSize, lastStatusByte, time);

        if (messSize <= 0)
            break;

        size -= messSize;
        data += messSize;

        result.addEvent (mm);

        const uint8 firstByte = *(mm.getRawData());
        if ((firstByte & 0xf0) != 0xf0)
            lastStatusByte = firstByte;
    }

    // use a sort that puts all the note-offs before note-ons that have the same time
    MidiFileHelpers::Sorter sorter;
    result.list.sort (sorter, true);

    addTrack (result);
    tracks.getLast()->updateMatchedPairs();
}

//==============================================================================
void MidiFile::convertTimestampTicksToSeconds()
{
    MidiMessageSequence tempoEvents;
    findAllTempoEvents (tempoEvents);
    findAllTimeSigEvents (tempoEvents);

    if (timeFormat != 0)
    {
        for (int i = 0; i < tracks.size(); ++i)
        {
            const MidiMessageSequence& ms = *tracks.getUnchecked(i);

            for (int j = ms.getNumEvents(); --j >= 0;)
            {
                MidiMessage& m = ms.getEventPointer(j)->message;

                m.setTimeStamp (MidiFileHelpers::convertTicksToSeconds (m.getTimeStamp(),
                                                                        tempoEvents,
                                                                        timeFormat));
            }
        }
    }
}

//==============================================================================
bool MidiFile::writeTo (OutputStream& out)
{
    out.writeIntBigEndian ((int) ByteOrder::bigEndianInt ("MThd"));
    out.writeIntBigEndian (6);
    out.writeShortBigEndian (1); // type
    out.writeShortBigEndian ((short) tracks.size());
    out.writeShortBigEndian (timeFormat);

    for (int i = 0; i < tracks.size(); ++i)
        writeTrack (out, i);

    out.flush();
    return true;
}

void MidiFile::writeTrack (OutputStream& mainOut, const int trackNum)
{
    MemoryOutputStream out;
    const MidiMessageSequence& ms = *tracks.getUnchecked (trackNum);

    int lastTick = 0;
    uint8 lastStatusByte = 0;

    for (int i = 0; i < ms.getNumEvents(); ++i)
    {
        const MidiMessage& mm = ms.getEventPointer(i)->message;

        if (! mm.isEndOfTrackMetaEvent())
        {
            const int tick = roundToInt (mm.getTimeStamp());
            const int delta = jmax (0, tick - lastTick);
            MidiFileHelpers::writeVariableLengthInt (out, (uint32) delta);
            lastTick = tick;

            const uint8* data = mm.getRawData();
            int dataSize = mm.getRawDataSize();

            const uint8 statusByte = data[0];

            if (statusByte == lastStatusByte
                 && (statusByte & 0xf0) != 0xf0
                 && dataSize > 1
                 && i > 0)
            {
                ++data;
                --dataSize;
            }
            else if (statusByte == 0xf0)  // Write sysex message with length bytes.
            {
                out.writeByte ((char) statusByte);

                ++data;
                --dataSize;

                MidiFileHelpers::writeVariableLengthInt (out, (uint32) dataSize);
            }

            out.write (data, (size_t) dataSize);
            lastStatusByte = statusByte;
        }
    }

    {
        out.writeByte (0); // (tick delta)
        const MidiMessage m (MidiMessage::endOfTrack());
        out.write (m.getRawData(), (size_t) m.getRawDataSize());
    }

    mainOut.writeIntBigEndian ((int) ByteOrder::bigEndianInt ("MTrk"));
    mainOut.writeIntBigEndian ((int) out.getDataSize());
    mainOut << out;
}