Another step towards fixing MIDI Clock sync
* Fix reset on timeout: Reset needs to be called before processing any messages. * use DLL to compute BPM (remove 1st order LPF) * set BPM before calculating ppqn * Fix speed at 1.0, change BPM only. MIDI clock must vari-speed (which changes pitch). MIDI clock is acts as "Conductor" that specifies when a beat happens at a given wall-clock time. timecode moves at speed 1.0 only the BPM changes.
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@ -129,8 +129,6 @@ MIDIClock_TransportMaster::pre_process (MIDI::pframes_t nframes, samplepos_t now
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DEBUG_TRACE (DEBUG::MidiClock, string_compose ("preprocess with lt = %1 @ %2, running ? %3\n", current.timestamp, now, _running));
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_midi_port->read_and_parse_entire_midi_buffer_with_no_speed_adjustment (nframes, parser, now);
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/* no clock messages ever, or no clock messages for 1/4 second ? conclude that its stopped */
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if (!current.timestamp || one_ppqn_in_samples == 0 || (now > current.timestamp && ((now - current.timestamp) > (ENGINE->sample_rate() / 4)))) {
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@ -140,9 +138,10 @@ MIDIClock_TransportMaster::pre_process (MIDI::pframes_t nframes, samplepos_t now
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midi_clock_count = 0;
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DEBUG_TRACE (DEBUG::MidiClock, string_compose ("No MIDI Clock messages received for some time, stopping! ts = %1 @ %2 ppqn = %3\n", current.timestamp, now, one_ppqn_in_samples));
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return;
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}
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_midi_port->read_and_parse_entire_midi_buffer_with_no_speed_adjustment (nframes, parser, now);
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if (session_pos) {
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const samplepos_t current_pos = current.position + ((now - current.timestamp) * current.speed);
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_current_delta = current_pos - *session_pos;
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@ -223,7 +222,7 @@ MIDIClock_TransportMaster::update_midi_clock (Parser& /*parser*/, samplepos_t ti
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e2 = timestamp - current.timestamp;
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const samplecnt_t samples_per_quarter = e2 * 24;
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const samplecnt_t samples_per_quarter = e2 * ppqn;
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double bpm = (ENGINE->sample_rate() * 60.0) / samples_per_quarter;
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if (bpm < 1 || bpm > 999) {
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@ -255,43 +254,30 @@ MIDIClock_TransportMaster::update_midi_clock (Parser& /*parser*/, samplepos_t ti
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t1 += b * e + e2;
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e2 += c * e;
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const double samples_per_quarter = (timestamp - current.timestamp) * 24.0;
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const double instantaneous_bpm = (ENGINE->sample_rate() * 60.0) / samples_per_quarter;
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const double samples_per_quarter = (t1 - t0) * ppqn;
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const double predicted_clock_interval_in_samples = (t1 - t0) * 24;
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_bpm = (ENGINE->sample_rate() * 60.0) / samples_per_quarter;
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calculate_filter_coefficients (_bpm);
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/* _speed is relative to session tempo map */
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double speed = predicted_clock_interval_in_samples / one_ppqn_in_samples;
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/* _bpm (really, _qpm) is absolute */
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/* detect substantial changes in apparent tempo (defined as a
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* change of more than 20% of the current tempo.
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/* when rolling speed is always 1.0. The transport moves at wall-clock
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* speed. What changes is the music-time (BPM), not the speed.
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*/
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const double lpf_coeff = 0.063;
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if (fabs (instantaneous_bpm - _bpm) > (0.20 * _bpm)) {
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_bpm = instantaneous_bpm;
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} else {
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_bpm += lpf_coeff * (instantaneous_bpm - _bpm);
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if (TransportMasterManager::instance().current().get() == this) {
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/* TODO always set tempo, even when there is a map */
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_session->maybe_update_tempo_from_midiclock_tempo (_bpm);
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}
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calculate_filter_coefficients (_bpm);
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calculate_one_ppqn_in_samples_at (current.position);
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midi_clock_count++;
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if (_running) {
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DEBUG_TRACE (DEBUG::MidiClock, string_compose ("mclock running with speed = %1 bpm = %2\n", (t1 - t0) / one_ppqn_in_samples, _bpm));
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current.update (current.position + one_ppqn_in_samples, timestamp, speed);
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current.update (current.position + one_ppqn_in_samples, timestamp, 1.0);
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} else {
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DEBUG_TRACE (DEBUG::MidiClock, string_compose ("mclock stopped speed = %1 bpm = %2\n", (t1 - t0) / one_ppqn_in_samples, _bpm));
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current.update (current.position, timestamp, 0);
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}
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if (TransportMasterManager::instance().current().get() == this) {
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_session->maybe_update_tempo_from_midiclock_tempo (_bpm);
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}
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}
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DEBUG_TRACE (DEBUG::MidiClock, string_compose (
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