JUCE/modules/juce_audio_basics/midi/juce_MidiFile.cpp

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

   This file is part of the JUCE library.
   Copyright (c) 2017 - ROLI Ltd.

   JUCE is an open source library subject to commercial or open-source
   licensing.

   The code included in this file is provided under the terms of the ISC license
   http://www.isc.org/downloads/software-support-policy/isc-license. Permission
   To use, copy, modify, and/or distribute this software for any purpose with or
   without fee is hereby granted provided that the above copyright notice and
   this permission notice appear in all copies.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

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

namespace juce
{

namespace MidiFileHelpers
{
    static void writeVariableLengthInt (OutputStream& out, uint32 v)
    {
        auto 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
    {
        auto 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;
        }

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

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

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

            if (eventTime >= time)
                break;

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

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

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

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

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

                ++i;
            }
        }

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

    template <typename MethodType>
    static void findAllMatchingEvents (const OwnedArray<MidiMessageSequence>& tracks,
                                       MidiMessageSequence& results,
                                       MethodType method)
    {
        for (auto* track : tracks)
        {
            auto numEvents = track->getNumEvents();

            for (int j = 0; j < numEvents; ++j)
            {
                auto& m = track->getEventPointer(j)->message;

                if ((m.*method)())
                    results.addEvent (m);
            }
        }
    }
}

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

MidiFile::MidiFile (const MidiFile& other)  : timeFormat (other.timeFormat)
{
    tracks.addCopiesOf (other.tracks);
}

MidiFile& MidiFile::operator= (const MidiFile& other)
{
    tracks.clear();
    tracks.addCopiesOf (other.tracks);
    timeFormat = other.timeFormat;
    return *this;
}

MidiFile::MidiFile (MidiFile&& other)
    : tracks (static_cast<OwnedArray<MidiMessageSequence>&&> (other.tracks)),
      timeFormat (other.timeFormat)
{
}

MidiFile& MidiFile::operator= (MidiFile&& other)
{
    tracks = static_cast<OwnedArray<MidiMessageSequence>&&> (other.tracks);
    timeFormat = other.timeFormat;
    return *this;
}

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

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

const MidiMessageSequence* MidiFile::getTrack (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 (int ticks) noexcept
{
    timeFormat = (short) ticks;
}

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

//==============================================================================
void MidiFile::findAllTempoEvents (MidiMessageSequence& results) const
{
    MidiFileHelpers::findAllMatchingEvents (tracks, results, &MidiMessage::isTempoMetaEvent);
}

void MidiFile::findAllTimeSigEvents (MidiMessageSequence& results) const
{
    MidiFileHelpers::findAllMatchingEvents (tracks, results, &MidiMessage::isTimeSignatureMetaEvent);
}

void MidiFile::findAllKeySigEvents (MidiMessageSequence& results) const
{
    MidiFileHelpers::findAllMatchingEvents (tracks, results, &MidiMessage::isKeySignatureMetaEvent);
}

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

    for (auto* ms : tracks)
        t = jmax (t, ms->getEndTime());

    return t;
}

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

    const int maxSensibleMidiFileSize = 200 * 1024 * 1024;

    // (put a sanity-check on the file size, as midi files are generally small)
    if (sourceStream.readIntoMemoryBlock (data, maxSensibleMidiFileSize))
    {
        auto size = data.getSize();
        auto 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)
            {
                auto chunkType = (int) ByteOrder::bigEndianInt (d);
                d += 4;
                auto chunkSize = (int) ByteOrder::bigEndianInt (d);
                d += 4;

                if (chunkSize <= 0)
                    break;

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

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

            return true;
        }
    }

    return false;
}

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

    MidiMessageSequence result;

    while (size > 0)
    {
        int bytesUsed;
        auto 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);

        auto firstByte = *(mm.getRawData());

        if ((firstByte & 0xf0) != 0xf0)
            lastStatusByte = firstByte;
    }

    // sort so that we put all the note-offs before note-ons that have the same time
    std::stable_sort (result.list.begin(), result.list.end(),
                      [] (const MidiMessageSequence::MidiEventHolder* a,
                          const MidiMessageSequence::MidiEventHolder* b)
    {
        auto t1 = a->message.getTimeStamp();
        auto t2 = b->message.getTimeStamp();

        if (t1 < t2)  return true;
        if (t2 < t1)  return false;

        return a->message.isNoteOff() && b->message.isNoteOn();
    });

    addTrack (result);

    if (createMatchingNoteOffs)
        tracks.getLast()->updateMatchedPairs();
}

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

    if (timeFormat != 0)
    {
        for (auto* ms : tracks)
        {
            for (int j = ms->getNumEvents(); --j >= 0;)
            {
                auto& m = ms->getEventPointer(j)->message;
                m.setTimeStamp (MidiFileHelpers::convertTicksToSeconds (m.getTimeStamp(), tempoEvents, timeFormat));
            }
        }
    }
}

//==============================================================================
bool MidiFile::writeTo (OutputStream& out, int midiFileType)
{
    jassert (midiFileType >= 0 && midiFileType <= 2);

    if (! out.writeIntBigEndian ((int) ByteOrder::bigEndianInt ("MThd"))) return false;
    if (! out.writeIntBigEndian (6))                                      return false;
    if (! out.writeShortBigEndian ((short) midiFileType))                 return false;
    if (! out.writeShortBigEndian ((short) tracks.size()))                return false;
    if (! out.writeShortBigEndian (timeFormat))                           return false;

    for (auto* ms : tracks)
        if (! writeTrack (out, *ms))
            return false;

    out.flush();
    return true;
}

bool MidiFile::writeTrack (OutputStream& mainOut, const MidiMessageSequence& ms)
{
    MemoryOutputStream out;

    int lastTick = 0;
    uint8 lastStatusByte = 0;
    bool endOfTrackEventWritten = false;

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

        if (mm.isEndOfTrackMetaEvent())
            endOfTrackEventWritten = true;

        auto tick = roundToInt (mm.getTimeStamp());
        auto delta = jmax (0, tick - lastTick);
        MidiFileHelpers::writeVariableLengthInt (out, (uint32) delta);
        lastTick = tick;

        auto* data = mm.getRawData();
        auto dataSize = mm.getRawDataSize();
        auto 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;
    }

    if (! endOfTrackEventWritten)
    {
        out.writeByte (0); // (tick delta)
        auto m = MidiMessage::endOfTrack();
        out.write (m.getRawData(), (size_t) m.getRawDataSize());
    }

    if (! mainOut.writeIntBigEndian ((int) ByteOrder::bigEndianInt ("MTrk"))) return false;
    if (! mainOut.writeIntBigEndian ((int) out.getDataSize()))                return false;

    mainOut << out;

    return true;
}

} // namespace juce