midi_clock_slave.cc

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/*
    Copyright (C) 2008 Paul Davis
    Author: Hans Baier

    This program 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 2 of the License, or
    (at your option) any later version.

    This program 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, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

#include <cmath>
#include <errno.h>
#include <sys/types.h>
#include <unistd.h>
#include "pbd/error.h"
#include "pbd/failed_constructor.h"
#include "pbd/pthread_utils.h"
#include "pbd/convert.h"

#include "midi++/port.h"

#include "ardour/debug.h"
#include "ardour/midi_buffer.h"
#include "ardour/midi_port.h"
#include "ardour/slave.h"
#include "ardour/tempo.h"

#include "i18n.h"

using namespace std;
using namespace ARDOUR;
using namespace MIDI;
using namespace PBD;

MIDIClock_Slave::MIDIClock_Slave (Session& s, MidiPort& p, int ppqn)
        : ppqn (ppqn)
        , bandwidth (2.0 / 60.0) // 1 BpM = 1 / 60 Hz
{
        session = (ISlaveSessionProxy *) new SlaveSessionProxy(s);
        rebind (p);
        reset ();
}

MIDIClock_Slave::MIDIClock_Slave (ISlaveSessionProxy* session_proxy, int ppqn)
        : session(session_proxy)
        , ppqn (ppqn)
        , bandwidth (2.0 / 60.0) // 1 BpM = 1 / 60 Hz
{
        reset ();
}

MIDIClock_Slave::~MIDIClock_Slave()
{
        delete session;
}

void
MIDIClock_Slave::rebind (MidiPort& port)
{
        DEBUG_TRACE (DEBUG::MidiClock, string_compose ("MIDIClock_Slave: connecting to port %1\n", port.name()));

        port_connections.drop_connections ();

        port.self_parser().timing.connect_same_thread (port_connections, boost::bind (&MIDIClock_Slave::update_midi_clock, this, _1, _2));
        port.self_parser().start.connect_same_thread (port_connections, boost::bind (&MIDIClock_Slave::start, this, _1, _2));
        port.self_parser().contineu.connect_same_thread (port_connections, boost::bind (&MIDIClock_Slave::contineu, this, _1, _2));
        port.self_parser().stop.connect_same_thread (port_connections, boost::bind (&MIDIClock_Slave::stop, this, _1, _2));
        port.self_parser().position.connect_same_thread (port_connections, boost::bind (&MIDIClock_Slave::position, this, _1, _2, 3));

}

void
MIDIClock_Slave::calculate_one_ppqn_in_frames_at(framepos_t time)
{
        const Tempo& current_tempo = session->tempo_map().tempo_at(time);
        double frames_per_beat = current_tempo.frames_per_beat(session->frame_rate());

        double quarter_notes_per_beat = 4.0 / current_tempo.note_type();
        double frames_per_quarter_note = frames_per_beat / quarter_notes_per_beat;

        one_ppqn_in_frames = frames_per_quarter_note / double (ppqn);
        // DEBUG_TRACE (DEBUG::MidiClock, string_compose ("at %1, one ppqn = %2\n", time, one_ppqn_in_frames));
}

ARDOUR::framepos_t
MIDIClock_Slave::calculate_song_position(uint16_t song_position_in_sixteenth_notes)
{
        framepos_t song_position_frames = 0;
        for (uint16_t i = 1; i <= song_position_in_sixteenth_notes; ++i) {
                // one quarter note contains ppqn pulses, so a sixteenth note is ppqn / 4 pulses
                calculate_one_ppqn_in_frames_at(song_position_frames);
                song_position_frames += one_ppqn_in_frames * (framepos_t)(ppqn / 4);
        }

        return song_position_frames;
}

void
MIDIClock_Slave::calculate_filter_coefficients()
{
        // omega = 2 * PI * Bandwidth / MIDI clock frame frequency in Hz
        omega = 2.0 * M_PI * bandwidth * one_ppqn_in_frames / session->frame_rate();
        b = 1.4142135623730950488 * omega;
        c = omega * omega;
}

void
MIDIClock_Slave::update_midi_clock (Parser& /*parser*/, framepos_t timestamp)
{
        // some pieces of hardware send MIDI Clock all the time
        if ( (!_starting) && (!_started) ) {
                return;
        }

        pframes_t cycle_offset = timestamp - session->sample_time_at_cycle_start();

        calculate_one_ppqn_in_frames_at(should_be_position);

        framepos_t elapsed_since_start = timestamp - first_timestamp;
        double error = 0;

        if (_starting || last_timestamp == 0) {
                midi_clock_count = 0;

                first_timestamp = timestamp;
                elapsed_since_start = should_be_position;

                DEBUG_TRACE (DEBUG::MidiClock, string_compose ("first clock message after start received @ %1\n", timestamp));

                // calculate filter coefficients
                calculate_filter_coefficients();

                // initialize DLL
                e2 = double(one_ppqn_in_frames) / double(session->frame_rate());
                t0 = double(elapsed_since_start) / double(session->frame_rate());
                t1 = t0 + e2;

                // let ardour go after first MIDI Clock Event
                _starting = false;
        } else {
                midi_clock_count++;
                should_be_position  += one_ppqn_in_frames;
                calculate_filter_coefficients();

                // calculate loop error
                // we use session->transport_frame() instead of t1 here
                // because t1 is used to calculate the transport speed,
                // so the loop will compensate for accumulating rounding errors
                error = (double(should_be_position) - (double(session->transport_frame()) + double(cycle_offset)));
                e = error / double(session->frame_rate());
                current_delta = error;

                // update DLL
                t0 = t1;
                t1 += b * e + e2;
                e2 += c * e;
        }

        DEBUG_TRACE (DEBUG::MidiClock, string_compose ("clock #%1 @ %2 should-be %3 transport %4 error %5 appspeed %6 "
                                                       "read-delta %7 should-be delta %8 t1-t0 %9 t0 %10 t1 %11 framerate %12 engine %13\n",
                                                       midi_clock_count,                                          // #
                                                       elapsed_since_start,                                       // @
                                                       should_be_position,                                        // should-be
                                                       session->transport_frame(),                                // transport
                                                       error,                                                     // error
                                                       ((t1 - t0) * session->frame_rate()) / one_ppqn_in_frames, // appspeed
                                                       timestamp - last_timestamp,                                // read delta
                                                       one_ppqn_in_frames,                                        // should-be delta
                                                       (t1 - t0) * session->frame_rate(),                         // t1-t0
                                                       t0 * session->frame_rate(),                                // t0
                                                       t1 * session->frame_rate(),                                // t1
                                                       session->frame_rate(),                                      // framerate
                                                       session->frame_time()

        ));

        last_timestamp = timestamp;
}

void
MIDIClock_Slave::start (Parser& /*parser*/, framepos_t timestamp)
{
        DEBUG_TRACE (DEBUG::MidiClock, string_compose ("MIDIClock_Slave got start message at time %1 engine time %2 transport_frame %3\n", timestamp, session->frame_time(), session->transport_frame()));

        if (!_started) {
                reset();

                _started = true;
                _starting = true;

                should_be_position = session->transport_frame();
        }
}

void
MIDIClock_Slave::reset ()
{
        DEBUG_TRACE (DEBUG::MidiClock, string_compose ("MidiClock_Slave reset(): calculated filter bandwidth is %1 for period size %2\n", bandwidth, session->frames_per_cycle()));

        should_be_position = session->transport_frame();
        last_timestamp = 0;

        _starting = true;
        _started  = true;

        // session->request_locate(0, false);
        current_delta = 0;
}

void
MIDIClock_Slave::contineu (Parser& /*parser*/, framepos_t /*timestamp*/)
{
        DEBUG_TRACE (DEBUG::MidiClock, "MIDIClock_Slave got continue message\n");

        if (!_started) {
                _starting = true;
                _started  = true;
        }
}


void
MIDIClock_Slave::stop (Parser& /*parser*/, framepos_t /*timestamp*/)
{
        DEBUG_TRACE (DEBUG::MidiClock, "MIDIClock_Slave got stop message\n");

        if (_started || _starting) {
                _starting = false;
                _started  = false;
                // locate to last MIDI clock position
                session->request_transport_speed(0.0);

                // we need to go back to the last MIDI beat (6 ppqn)
                // and lets hope the tempo didnt change in the meantime :)

                // begin at the should be position, because
                // that is the position of the last MIDI Clock
                // message and that is probably what the master
                // expects where we are right now
                framepos_t stop_position = should_be_position;

                // find out the last MIDI beat: go back #midi_clocks mod 6
                // and lets hope the tempo didnt change in those last 6 beats :)
                stop_position -= (midi_clock_count % 6) * one_ppqn_in_frames;

                session->request_locate(stop_position, false);
                should_be_position = stop_position;
                last_timestamp = 0;
        }
}

void
MIDIClock_Slave::position (Parser& /*parser*/, MIDI::byte* message, size_t size)
{
        // we are note supposed to get position messages while we are running
        // so lets be robust and ignore those
        if (_started || _starting) {
                return;
        }

        assert(size == 3);
        MIDI::byte lsb = message[1];
        MIDI::byte msb = message[2];
        assert((lsb <= 0x7f) && (msb <= 0x7f));

        uint16_t position_in_sixteenth_notes = (uint16_t(msb) << 7) | uint16_t(lsb);
        framepos_t position_in_frames = calculate_song_position(position_in_sixteenth_notes);

        DEBUG_TRACE (DEBUG::MidiClock, string_compose ("Song Position: %1 frames: %2\n", position_in_sixteenth_notes, position_in_frames));

        session->request_locate(position_in_frames, false);
        should_be_position  = position_in_frames;
        last_timestamp = 0;

}

bool
MIDIClock_Slave::locked () const
{
        return true;
}

bool
MIDIClock_Slave::ok() const
{
        return true;
}

bool
MIDIClock_Slave::starting() const
{
        return false;
}

bool
MIDIClock_Slave::stop_if_no_more_clock_events(framepos_t& pos, framepos_t now)
{
        /* no timecode for 1/4 second ? conclude that its stopped */
        if (last_timestamp &&
            now > last_timestamp &&
            now - last_timestamp > session->frame_rate() / 4) {
                DEBUG_TRACE (DEBUG::MidiClock, "No MIDI Clock frames received for some time, stopping!\n");
                pos = should_be_position;
                session->request_transport_speed (0);
                session->request_locate (should_be_position, false);
                return true;
        } else {
                return false;
        }
}

bool
MIDIClock_Slave::speed_and_position (double& speed, framepos_t& pos)
{
        if (!_started || _starting) {
                speed = 0.0;
                pos   = should_be_position;
                return true;
        }

        framepos_t engine_now = session->frame_time();

        if (stop_if_no_more_clock_events(pos, engine_now)) {
                return false;
        }

        // calculate speed
        speed = ((t1 - t0) * session->frame_rate()) / one_ppqn_in_frames;

        // provide a 0.1% deadzone to lock the speed
        if (fabs(speed - 1.0) <= 0.001)
                speed = 1.0;

        // calculate position
        if (engine_now > last_timestamp) {
                // we are in between MIDI clock messages
                // so we interpolate position according to speed
                framecnt_t elapsed = engine_now - last_timestamp;
                pos = (framepos_t) (should_be_position + double(elapsed) * speed);
        } else {
                // A new MIDI clock message has arrived this cycle
                pos = should_be_position;
        }

        DEBUG_TRACE (DEBUG::MidiClock, string_compose ("speed_and_position: speed %1 should-be %2 transport %3 \n", speed, pos, session->transport_frame()));

        return true;
}

ARDOUR::framecnt_t
MIDIClock_Slave::resolution() const
{
        // one beat
        return (framecnt_t) one_ppqn_in_frames * ppqn;
}

std::string
MIDIClock_Slave::approximate_current_delta() const
{
        char delta[80];
        if (last_timestamp == 0 || _starting) {
                snprintf(delta, sizeof(delta), "\u2012\u2012\u2012\u2012");
        } else {
                snprintf(delta, sizeof(delta), "\u0394<span foreground=\"green\" face=\"monospace\" >%s%s%" PRIi64 "</span>sm",
                                LEADINGZERO(abs(current_delta)), PLUSMINUS(-current_delta), abs(current_delta));
        }
        return std::string(delta);
}