metronome.cpp

Simple command line MIDI metronome.

Simple command line MIDI metronome

/*
    Standard MIDI simple metronome
    Copyright (C) 2006-2023, Pedro Lopez-Cabanillas <plcl@users.sf.net>
 
    This library is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.
 
    This library 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.
 
    You should have received a copy of the GNU General Public License
    along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
 
#ifndef METRONOME_H
#define METRONOME_H
 
#include <QObject>
#include <QString>
#include <QList>
#include <QReadWriteLock>
 
#include <drumstick/alsaevent.h>
#include <drumstick/alsaclient.h>
#include <drumstick/alsaqueue.h>
#include <drumstick/alsaport.h>
 
const int TEMPO_DEFAULT(120);
const int NOTE_DURATION(10);
const int RHYTHM_TS_NUM(4);
const int RHYTHM_TS_DEN(4);
const int METRONOME_CHANNEL(9);
const int METRONOME_STRONG_NOTE(34);
const int METRONOME_WEAK_NOTE(33);
const int METRONOME_VELOCITY(100);
const int METRONOME_PROGRAM(0);
const int METRONOME_RESOLUTION(240);
const int METRONOME_VOLUME(100);
const int METRONOME_PAN(64);
 
class Metronome : public QObject, public drumstick::ALSA::SequencerEventHandler
{
    Q_OBJECT
 
public:
    explicit Metronome(QObject *parent = nullptr);
    virtual ~Metronome();
    void play(QString tempo);
    bool stopped();
    void stop();
    void subscribe(const QString& portName);
    void shutupSound();
 
    void sendControlChange( int cc, int value );
    void sendInitialControls();
    void metronome_note(int note, int tick);
    void metronome_echo(int tick);
    void metronome_pattern(int tick);
    void metronome_event_output(drumstick::ALSA::SequencerEvent* ev);
    void metronome_schedule_event(drumstick::ALSA::SequencerEvent* ev, int tick, bool lb);
    void metronome_set_program();
    void metronome_set_tempo();
    void metronome_set_controls();
 
    // SequencerEventHandler interface
    void handleSequencerEvent( drumstick::ALSA::SequencerEvent* ev ) override;
 
private:
    int m_weak_note;
    int m_strong_note;
    int m_weak_velocity;
    int m_strong_velocity;
    int m_program;
    int m_channel;
    int m_volume;
    int m_pan;
    int m_resolution;
    int m_bpm;
    int m_ts_num; /* time signature: numerator */
    int m_ts_div; /* time signature: denominator */
    int m_noteDuration;
    int m_patternDuration;
 
    int m_portId;
    int m_queueId;
    int m_clientId;
    bool m_Stopped;
    QReadWriteLock m_mutex;
    drumstick::ALSA::MidiClient* m_Client;
    drumstick::ALSA::MidiPort* m_Port;
    drumstick::ALSA::MidiQueue* m_Queue;
};
 
#endif /*METRONOME_H*/

/*
    Standard MIDI simple metronome
    Copyright (C) 2006-2023, Pedro Lopez-Cabanillas <plcl@users.sf.net>
 
    This library is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.
 
    This library 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.
 
    You should have received a copy of the GNU General Public License
    along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
 
#include "metronome.h"
#include <QCommandLineParser>
#include <QCoreApplication>
#include <QDebug>
#include <QReadLocker>
#include <QStringList>
#include <QTextStream>
#include <QIODevice>
#include <QWriteLocker>
#include <QtAlgorithms>
#include <csignal>
#include <drumstick/alsatimer.h>
#include <drumstick/sequencererror.h>
 
#if (QT_VERSION >= QT_VERSION_CHECK(5, 15, 0))
#define right Qt::right
#define left Qt::left
#define endl Qt::endl
#endif
 
QTextStream cout(stdout, QIODevice::WriteOnly);
QTextStream cerr(stderr, QIODevice::WriteOnly);
 
using namespace drumstick::ALSA;
 
/* *************** *
 * Metronome class *
 * *************** */
 
Metronome::Metronome(QObject *parent) : QObject(parent),
    m_weak_note(METRONOME_WEAK_NOTE),
    m_strong_note(METRONOME_STRONG_NOTE),
    m_weak_velocity(METRONOME_VELOCITY),
    m_strong_velocity(METRONOME_VELOCITY),
    m_program(METRONOME_PROGRAM),
    m_channel(METRONOME_CHANNEL),
    m_volume(METRONOME_VOLUME),
    m_pan(METRONOME_PAN),
    m_resolution(METRONOME_RESOLUTION),
    m_bpm(TEMPO_DEFAULT),
    m_ts_num(RHYTHM_TS_NUM),
    m_ts_div(RHYTHM_TS_DEN),
    m_noteDuration(NOTE_DURATION),
    m_portId(-1),
    m_queueId(-1),
    m_clientId(-1),
    m_Stopped(true)
{
    QString name{QStringLiteral("Metronome")};
    m_Client = new MidiClient(this);
    m_Client->open();
    m_Client->setClientName(name);
    m_Client->setHandler(this);
    m_Port = new MidiPort(this);
    m_Port->attach( m_Client );
    m_Port->setPortName(name);
    m_Port->setCapability( SND_SEQ_PORT_CAP_READ |
                           SND_SEQ_PORT_CAP_SUBS_READ |
                           SND_SEQ_PORT_CAP_WRITE );
    m_Port->setPortType( SND_SEQ_PORT_TYPE_MIDI_GENERIC |
                         SND_SEQ_PORT_TYPE_APPLICATION );
    m_Queue = m_Client->createQueue(name);
    m_clientId = m_Client->getClientId();
    m_queueId = m_Queue->getId();
    m_portId = m_Port->getPortId();
    m_Port->setTimestamping(true);
    m_Port->setTimestampQueue(m_queueId);
    // Get and apply the best available timer
    TimerId best = Timer::bestGlobalTimerId();
    QueueTimer qtimer;
    qtimer.setId(best);
    m_Queue->setTimer(qtimer);
    // Start sequencer input
    m_Client->setRealTimeInput(false);
    m_Client->startSequencerInput();
}
 
Metronome::~Metronome()
{
    m_Port->detach();
    m_Client->close();
}
 
void Metronome::handleSequencerEvent( SequencerEvent *ev )
{
    if (ev->getSequencerType() == SND_SEQ_EVENT_USR0)
        metronome_pattern(static_cast<int>(ev->getTick()) + m_patternDuration);
    delete ev;
}
 
void Metronome::metronome_event_output(SequencerEvent* ev)
{
    ev->setSource(static_cast<unsigned char>(m_portId));
    ev->setSubscribers();
    ev->setDirect();
    m_Client->outputDirect(ev);
}
 
void Metronome::sendControlChange(int cc, int value)
{
    ControllerEvent ev(m_channel, cc, value);
    metronome_event_output(&ev);
}
 
void Metronome::sendInitialControls()
{
    metronome_set_program();
    metronome_set_controls();
    metronome_set_tempo();
}
 
void Metronome::metronome_set_program()
{
    ProgramChangeEvent ev(m_channel, m_program);
    metronome_event_output(&ev);
}
 
void Metronome::metronome_schedule_event(SequencerEvent* ev, int tick, bool lb)
{
    ev->setSource(static_cast<unsigned char>(m_portId));
    if (lb) // loop back
        ev->setDestination(static_cast<unsigned char>(m_clientId), static_cast<unsigned char>(m_portId));
    else
        ev->setSubscribers();
    ev->scheduleTick(m_queueId, tick, false);
    m_Client->outputDirect(ev);
}
 
void Metronome::metronome_note(int note, int tick)
{
    NoteEvent ev(m_channel, note, METRONOME_VELOCITY, m_noteDuration);
    metronome_schedule_event(&ev, tick, false);
}
 
void Metronome::metronome_echo(int tick)
{
    SystemEvent ev(SND_SEQ_EVENT_USR0);
    metronome_schedule_event(&ev, tick, true);
}
 
void Metronome::metronome_pattern(int tick)
{
    int j, t, duration;
    t = tick;
    duration = m_resolution * 4 / m_ts_div;
    for (j = 0; j < m_ts_num; j++) {
        metronome_note(j ? m_weak_note : m_strong_note, t);
        t += duration;
    }
    metronome_echo(t);
}
 
void Metronome::metronome_set_tempo()
{
    QueueTempo t = m_Queue->getTempo();
    t.setPPQ(m_resolution);
    t.setNominalBPM(m_bpm);
    m_Queue->setTempo(t);
    m_Client->drainOutput();
}
 
void Metronome::metronome_set_controls()
{
    sendControlChange(MIDI_CTL_MSB_MAIN_VOLUME, m_volume);
    sendControlChange(MIDI_CTL_MSB_PAN, m_pan);
}
 
void Metronome::subscribe(const QString& portName)
{
    m_Port->subscribeTo(portName);
}
 
bool Metronome::stopped()
{
    QReadLocker locker(&m_mutex);
    return m_Stopped;
}
 
void Metronome::stop()
{
    QWriteLocker locker(&m_mutex);
    m_Stopped = true;
    m_Client->dropOutput();
}
 
void Metronome::shutupSound()
{
    sendControlChange( MIDI_CTL_ALL_NOTES_OFF, 0 );
    sendControlChange( MIDI_CTL_ALL_SOUNDS_OFF, 0 );
}
 
void Metronome::play(QString tempo)
{
    bool ok;
    m_Stopped = false;
    m_patternDuration = m_resolution * 4 / m_ts_div * m_ts_num;
    m_bpm = tempo.toInt(&ok);
    if (!ok) m_bpm = TEMPO_DEFAULT;
    cout << "Metronome playing. " << m_bpm << " bpm" << endl;
    cout << "Press Ctrl+C to exit" << endl;
    try {
        sendInitialControls();
        m_Queue->start();
        metronome_pattern(0);
        metronome_pattern(m_patternDuration);
        while (!stopped())
            sleep(1);
    } catch (const SequencerError& err) {
        cerr << "SequencerError exception. Error code: " << err.code()
             << " (" << err.qstrError() << ")" << endl;
        cerr << "Location: " << err.location() << endl;
    }
}
 
static Metronome* metronome = nullptr;
 
void signalHandler(int sig)
{
    if (sig == SIGINT)
        qDebug() << "Caught a SIGINT. Exiting";
    else if (sig == SIGTERM)
        qDebug() << "Caught a SIGTERM. Exiting";
    if (metronome != nullptr) {
        metronome->stop();
        metronome->shutupSound();
    }
}
 
int main(int argc, char **argv)
{
    const QString PGM_NAME = QStringLiteral("drumstick-metronome");
    const QString PGM_DESCRIPTION = QStringLiteral("ALSA based command line metronome");
    const QString ERRORSTR = QStringLiteral("Fatal error from the ALSA sequencer. "
        "This usually happens when the kernel doesn't have ALSA support, "
        "or the device node (/dev/snd/seq) doesn't exists, "
        "or the kernel module (snd_seq) is not loaded. "
        "Please check your ALSA/MIDI configuration.");
 
    signal(SIGINT, signalHandler);
    signal(SIGTERM, signalHandler);
 
    QCoreApplication app(argc, argv);
    QCoreApplication::setApplicationName(PGM_NAME);
    QCoreApplication::setApplicationVersion(QStringLiteral(QT_STRINGIFY(VERSION)));
 
    QCommandLineParser parser;
    parser.setApplicationDescription(PGM_DESCRIPTION);
    auto helpOption = parser.addHelpOption();
    auto versionOption = parser.addVersionOption();
    QCommandLineOption portOption({"p","port"}, "Destination, MIDI port identifier.", "client:port");
    parser.addOption(portOption);
    QCommandLineOption bpmOption({"b","bpm"}, "Tempo, in beats per minute (default=120).", "BPM", "120");
    parser.addOption(bpmOption);
    parser.process(app);
 
    if (parser.isSet(versionOption) || parser.isSet(helpOption)) {
        return 0;
    }
 
    try {
        metronome = new Metronome();
        if (parser.isSet(portOption)) {
            QString port = parser.value(portOption);
            metronome->subscribe(port);
        } else {
            cerr << "Destination Port is mandatory" << endl;
            parser.showHelp();
        }
 
        QString bpm("120");
        if (parser.isSet(bpmOption)) {
            bpm = parser.value(bpmOption);
        }
        metronome->play(bpm);
 
    } catch (const SequencerError& ex) {
        cerr << ERRORSTR << " Returned error was: " << ex.qstrError() << endl;
    } catch (...) {
        cerr << ERRORSTR << endl;
    }
    delete metronome;
    return 0;
}