* MIDI clock slave implementation with delay locked loop (DLL) seems to work well
* added option to class Slave / Session::process that a slave can have total control over transport speed git-svn-id: svn://localhost/ardour2/branches/3.0@4385 d708f5d6-7413-0410-9779-e7cbd77b26cf
This commit is contained in:
Hans Baier
parent
be668e55e8
commit
5f5a570e50
@ -148,6 +148,11 @@ class Slave {
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* the slave returns
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*/
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virtual bool is_always_synced() const { return false; }
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/**
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* @return - whether ARDOUR should use the slave speed without any adjustments
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*/
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virtual bool give_slave_full_control_over_transport_speed() const { return false; }
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};
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struct SafeTime {
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@ -219,6 +224,7 @@ class MIDIClock_Slave : public Slave, public sigc::trackable {
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nframes_t resolution() const;
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bool requires_seekahead () const { return false; }
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bool give_slave_full_control_over_transport_speed() const { return true; }
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private:
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Session& session;
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@ -231,20 +237,32 @@ class MIDIClock_Slave : public Slave, public sigc::trackable {
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/// the duration of one ppqn in frame time
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double one_ppqn_in_frames;
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/// the timestamp of the first MIDI clock message
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nframes_t first_timestamp;
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/// the time stamp and transport position of the last inbound MIDI clock message
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nframes_t last_timestamp;
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double last_position;
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/// The duration of the current MIDI clock frame in frames
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nframes_t current_midi_clock_frame_duration;
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//the delay locked loop (DLL), see www.kokkinizita.net/papers/usingdll.pdf
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/// how many MIDI clock frames to average over
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static const int32_t accumulator_size = 1;
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double accumulator[accumulator_size];
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int32_t accumulator_index;
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/// time at the beginning of the MIDI clock frame
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double t0;
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/// the running average of current_midi_clock_frame_duration
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double average_midi_clock_frame_duration;
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/// calculated end of the MIDI clock frame
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double t1;
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/// loop error = real value - expected value
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double e;
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/// second order loop error
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double e2;
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/// DLL filter bandwidth
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double bandwidth;
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/// DLL filter coefficients
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double b, c, omega;
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void reset ();
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void start (MIDI::Parser& parser, nframes_t timestamp);
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@ -252,6 +270,7 @@ class MIDIClock_Slave : public Slave, public sigc::trackable {
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// we can't use continue because it is a C++ keyword
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void contineu (MIDI::Parser& parser, nframes_t timestamp);
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void calculate_one_ppqn_in_frames_at(nframes_t time);
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void calculate_filter_coefficients();
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void update_midi_clock (MIDI::Parser& parser, nframes_t timestamp);
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void read_current (SafeTime *) const;
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bool stop_if_no_more_clock_events(nframes_t& pos, nframes_t now);
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@ -44,14 +44,10 @@ using namespace PBD;
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MIDIClock_Slave::MIDIClock_Slave (Session& s, MIDI::Port& p, int ppqn)
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: session (s)
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, ppqn (ppqn)
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, accumulator_index (0)
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, average_midi_clock_frame_duration (0.0)
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, bandwidth (30.0 / 60.0) // 1 BpM = 1 / 60 Hz
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{
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rebind (p);
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reset ();
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for(int i = 0; i < accumulator_size; i++)
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accumulator[i]=0.0;
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}
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MIDIClock_Slave::~MIDIClock_Slave()
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@ -92,56 +88,79 @@ MIDIClock_Slave::calculate_one_ppqn_in_frames_at(nframes_t time)
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one_ppqn_in_frames = frames_per_quarter_note / double (ppqn);
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}
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void
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MIDIClock_Slave::calculate_filter_coefficients()
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{
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// omega = 2 * PI * Bandwidth / MIDI clock frame frequency in Hz
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omega = 2.0 * 3.14159265358979323846 * bandwidth * one_ppqn_in_frames / session.frame_rate();
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b = 1.4142135623730950488 * omega;
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c = omega * omega;
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}
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void
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MIDIClock_Slave::update_midi_clock (Parser& parser, nframes_t timestamp)
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{
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// the number of midi clock messages (zero-based)
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static long midi_clock_count;
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calculate_one_ppqn_in_frames_at(last_position);
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// for the first MIDI clock event we don't have any past
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// data, so we assume a sane tempo
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if(_starting) {
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current_midi_clock_frame_duration = one_ppqn_in_frames;
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} else {
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current_midi_clock_frame_duration = timestamp - last_timestamp;
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}
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// moving average over incoming intervals
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accumulator[accumulator_index++] = current_midi_clock_frame_duration;
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if(accumulator_index == accumulator_size) {
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accumulator_index = 0;
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}
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average_midi_clock_frame_duration = 0.0;
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for(int i = 0; i < accumulator_size; i++) {
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average_midi_clock_frame_duration += accumulator[i];
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}
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average_midi_clock_frame_duration /= double(accumulator_size);
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#ifdef DEBUG_MIDI_CLOCK
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std::cerr
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<< " got MIDI Clock message at time " << timestamp
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<< " engine time: " << session.engine().frame_time()
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<< " transport position: " << session.transport_frame()
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<< " real delta: " << current_midi_clock_frame_duration
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<< " reference: " << one_ppqn_in_frames
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<< " average: " << average_midi_clock_frame_duration
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<< std::endl;
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#endif // DEBUG_MIDI_CLOCK
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nframes_t timestamp_relative_to_transport = timestamp - first_timestamp;
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if (_starting) {
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midi_clock_count = 0;
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assert(last_timestamp == 0);
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assert(last_position == 0);
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last_position = 0;
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last_timestamp = timestamp;
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first_timestamp = timestamp;
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timestamp_relative_to_transport = 0;
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// calculate filter coefficients
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calculate_filter_coefficients();
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// initialize DLL
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e2 = double(one_ppqn_in_frames) / double(session.frame_rate());
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t0 = double(timestamp_relative_to_transport) / double(session.frame_rate());
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t1 = t0 + e2;
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// let ardour go after first MIDI Clock Event
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_starting = false;
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session.request_transport_speed (1.0);
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} else {;
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last_position += double(one_ppqn_in_frames);
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last_timestamp = timestamp;
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} else {
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midi_clock_count++;
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last_position += one_ppqn_in_frames;
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calculate_filter_coefficients();
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// calculate loop error
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// we use session.transport_frame() instead of t1 here
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// because t1 is used to calculate the transport speed, and since this
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// is float, the loop will compensate for accumulating rounding errors
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e = (double(last_position) - double(session.transport_frame()))
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/ double(session.frame_rate());
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// update DLL
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t0 = t1;
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t1 += b * e + e2;
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e2 += c * e;
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}
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#ifdef DEBUG_MIDI_CLOCK
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std::cerr
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<< "MIDI Clock #" << midi_clock_count
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//<< "@" << timestamp
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<< " (transport-relative: " << timestamp_relative_to_transport << " should be: " << last_position << ", delta: " << (double(last_position) - double(session.transport_frame())) <<" )"
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<< " transport: " << session.transport_frame()
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//<< " engine: " << session.engine().frame_time()
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<< " real delta: " << timestamp - last_timestamp
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<< " reference: " << one_ppqn_in_frames
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<< " t1-t0: " << (t1 -t0) * session.frame_rate()
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<< " t0: " << t0 * session.frame_rate()
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<< " t1: " << t1 * session.frame_rate()
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<< " frame-rate: " << session.frame_rate()
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<< std::endl;
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#endif // DEBUG_MIDI_CLOCK
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last_timestamp = timestamp;
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}
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void
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@ -151,18 +170,6 @@ MIDIClock_Slave::start (Parser& parser, nframes_t timestamp)
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cerr << "MIDIClock_Slave got start message at time " << timestamp << " session time: " << session.engine().frame_time() << endl;
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#endif
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if(!locked()) {
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cerr << "Did not start because not locked!" << endl;
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return;
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}
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// initialize accumulator to sane values
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calculate_one_ppqn_in_frames_at(0);
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for(int i = 0; i < accumulator_size; i++) {
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accumulator[i] = one_ppqn_in_frames;
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}
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last_position = 0;
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last_timestamp = 0;
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@ -187,8 +194,6 @@ MIDIClock_Slave::stop (Parser& parser, nframes_t timestamp)
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std::cerr << "MIDIClock_Slave got stop message" << endl;
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#endif
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current_midi_clock_frame_duration = 0;
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last_position = 0;
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last_timestamp = 0;
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@ -250,18 +255,10 @@ MIDIClock_Slave::speed_and_position (float& speed, nframes_t& pos)
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return false;
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}
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#ifdef DEBUG_MIDI_CLOCK
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cerr << "speed_and_position: engine time: " << engine_now << " last message timestamp: " << last_timestamp;
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#endif
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// calculate speed
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double speed_double = one_ppqn_in_frames / average_midi_clock_frame_duration;
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double speed_double = ((t1 - t0) * session.frame_rate()) / one_ppqn_in_frames;
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speed = float(speed_double);
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#ifdef DEBUG_MIDI_CLOCK
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cerr << " final speed: " << speed;
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#endif
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// calculate position
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if (engine_now > last_timestamp) {
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// we are in between MIDI clock messages
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@ -273,12 +270,6 @@ MIDIClock_Slave::speed_and_position (float& speed, nframes_t& pos)
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pos = last_position;
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}
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#ifdef DEBUG_MIDI_CLOCK
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cerr << " transport position engine_now: " << session.transport_frame();
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cerr << " calculated position: " << pos;
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cerr << endl;
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#endif
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return true;
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}
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@ -542,16 +542,19 @@ Session::follow_slave (nframes_t nframes, nframes_t offset)
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float adjusted_speed = slave_speed + (delta / float(_current_frame_rate));
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#ifdef DEBUG_SLAVES
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cerr << "adjust using " << delta
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<< " towards " << adjusted_speed
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<< " ratio = " << adjusted_speed / slave_speed
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<< " current = " << _transport_speed
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<< " slave @ " << slave_speed
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<< endl;
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#endif
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request_transport_speed (adjusted_speed);
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if (_slave->give_slave_full_control_over_transport_speed()) {
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request_transport_speed(slave_speed);
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} else {
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request_transport_speed(adjusted_speed);
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#ifdef DEBUG_SLAVES
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cerr << "adjust using " << delta
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<< " towards " << adjusted_speed
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<< " ratio = " << adjusted_speed / slave_speed
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<< " current = " << _transport_speed
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<< " slave @ " << slave_speed
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<< endl;
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#endif
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}
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if (abs(average_slave_delta) > (long) _slave->resolution()) {
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cerr << "average slave delta greater than slave resolution, going to silent motion\n";
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@ -576,9 +579,9 @@ Session::follow_slave (nframes_t nframes, nframes_t offset)
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}
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silent_motion:
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#ifdef DEBUG_SLAVES
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#ifdef DEBUG_SLAVES
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cerr << "reached silent_motion:" <<endl;
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#endif
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#endif
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if (slave_speed && _transport_speed) {
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@ -621,9 +624,9 @@ Session::follow_slave (nframes_t nframes, nframes_t offset)
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noroll:
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/* don't move at all */
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#ifdef DEBUG_SLAVES
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#ifdef DEBUG_SLAVES
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cerr << "reached no_roll:" <<endl;
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#endif
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#endif
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no_roll (nframes, 0);
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return false;
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}
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@ -701,9 +704,9 @@ Session::track_slave_state(
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if (slave_state == Waiting) {
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#ifdef DEBUG_SLAVES
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#ifdef DEBUG_SLAVES
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cerr << "waiting at " << slave_transport_frame << endl;
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#endif
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#endif
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if (slave_transport_frame >= slave_wait_end) {
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#ifdef DEBUG_SLAVES
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cerr << "\tstart at " << _transport_frame << endl;
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@ -741,9 +744,9 @@ Session::track_slave_state(
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if (slave_state == Running && _transport_speed == 0.0f) {
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#ifdef DEBUG_SLAVES
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#ifdef DEBUG_SLAVES
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cerr << "slave starts transport\n";
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#endif
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#endif
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start_transport ();
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}
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@ -753,10 +756,10 @@ Session::track_slave_state(
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if (_transport_speed != 0.0f) {
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#ifdef DEBUG_SLAVES
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#ifdef DEBUG_SLAVES
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cerr << "slave stops transport: " << slave_speed << " frame: " << slave_transport_frame
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<< " tf = " << _transport_frame << endl;
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#endif
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#endif
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if (Config->get_slave_source() == JACK) {
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last_stop_frame = _transport_frame;
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@ -766,9 +769,9 @@ Session::track_slave_state(
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}
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if (slave_transport_frame != _transport_frame) {
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#ifdef DEBUG_SLAVES
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#ifdef DEBUG_SLAVES
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cerr << "slave stopped, move to " << slave_transport_frame << endl;
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#endif
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#endif
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force_locate (slave_transport_frame, false);
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}
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