2 Copyright (C) 2002 Paul Davis
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 #ifndef __ardour_slave_h__
21 #define __ardour_slave_h__
25 #include <glibmm/thread.h>
27 #include <jack/jack.h>
29 #include "pbd/signals.h"
31 #include "ardour/types.h"
32 #include "midi++/parser.h"
33 #include "midi++/types.h"
49 * @brief The Slave interface can be used to sync ARDOURs tempo to an external source
50 * like MTC, MIDI Clock, etc.
52 * The name of the interface may be a bit misleading: A subclass of Slave actually
53 * acts as a time master for ARDOUR, that means ARDOUR will try to follow the
54 * speed and transport position of the implementation of Slave.
55 * Therefore it is rather that class, that makes ARDOUR a slave by connecting it
56 * to its external time master.
64 * This is the most important function to implement:
65 * Each process cycle, Session::follow_slave will call this method.
66 * and after the method call they should
68 * Session::follow_slave will then try to follow the given
69 * <em>position</em> using a delay locked loop (DLL),
70 * starting with the first given transport speed.
71 * If the values of speed and position contradict each other,
72 * ARDOUR will always follow the position and disregard the speed.
73 * Although, a correct speed is important so that ARDOUR
74 * can sync to the master time source quickly.
76 * For background information on delay locked loops,
77 * see http://www.kokkinizita.net/papers/usingdll.pdf
79 * The method has the following precondition:
82 * Slave::ok() should return true, otherwise playback will stop
83 * immediately and the method will not be called
86 * when the references speed and position are passed into the Slave
87 * they are uninitialized
91 * After the method call the following postconditions should be met:
94 * The first position value on transport start should be 0,
95 * otherwise ARDOUR will try to locate to the new position
96 * rather than move to it
99 * the references speed and position should be assigned
100 * to the Slaves current requested transport speed
101 * and transport position.
104 * Slave::resolution() should be greater than the maximum distance of
105 * ARDOURs transport position to the slaves requested transport position.
107 * <li>Slave::locked() should return true, otherwise Session::no_roll will be called</li>
108 * <li>Slave::starting() should be false, otherwise the transport will not move until it becomes true</li> *
111 * @param speed - The transport speed requested
112 * @param position - The transport position requested
113 * @return - The return value is currently ignored (see Session::follow_slave)
115 virtual bool speed_and_position (double& speed, framepos_t& position) = 0;
118 * reports to ARDOUR whether the Slave is currently synced to its external
121 * @return - when returning false, the transport will stop rolling
123 virtual bool locked() const = 0;
126 * reports to ARDOUR whether the slave is in a sane state
128 * @return - when returning false, the transport will be stopped and the slave
129 * disconnected from ARDOUR.
131 virtual bool ok() const = 0;
134 * reports to ARDOUR whether the slave is in the process of starting
137 * @return - when returning false, transport will not move until this method returns true
139 virtual bool starting() const { return false; }
142 * @return - the timing resolution of the Slave - If the distance of ARDOURs transport
143 * to the slave becomes greater than the resolution, sound will stop
145 virtual framecnt_t resolution() const = 0;
148 * @return - when returning true, ARDOUR will wait for seekahead_distance() before transport
151 virtual bool requires_seekahead () const = 0;
154 * @return the number of frames that this slave wants to seek ahead. Relevant
155 * only if requires_seekahead() returns true.
158 virtual framepos_t seekahead_distance() const { return 0; }
161 * @return - when returning true, ARDOUR will use transport speed 1.0 no matter what
164 virtual bool is_always_synced() const { return false; }
167 * @return - whether ARDOUR should use the slave speed without any adjustments
169 virtual bool give_slave_full_control_over_transport_speed() const { return false; }
172 /// We need this wrapper for testability, it's just too hard to mock up a session class
173 class ISlaveSessionProxy {
175 virtual ~ISlaveSessionProxy() {}
176 virtual TempoMap& tempo_map() const { return *((TempoMap *) 0); }
177 virtual framecnt_t frame_rate() const { return 0; }
178 virtual framepos_t audible_frame () const { return 0; }
179 virtual framepos_t transport_frame () const { return 0; }
180 virtual pframes_t frames_since_cycle_start () const { return 0; }
181 virtual framepos_t frame_time () const { return 0; }
183 virtual void request_locate (framepos_t /*frame*/, bool with_roll = false) {
186 virtual void request_transport_speed (double /*speed*/) {}
190 /// The Session Proxy for use in real Ardour
191 class SlaveSessionProxy : public ISlaveSessionProxy {
195 SlaveSessionProxy(Session &s) : session(s) {}
197 TempoMap& tempo_map() const;
198 framecnt_t frame_rate() const;
199 framepos_t audible_frame () const;
200 framepos_t transport_frame () const;
201 pframes_t frames_since_cycle_start () const;
202 framepos_t frame_time () const;
204 void request_locate (framepos_t frame, bool with_roll = false);
205 void request_transport_speed (double speed);
211 framepos_t timestamp;
224 class MTC_Slave : public Slave {
226 MTC_Slave (Session&, MIDI::Port&);
229 void rebind (MIDI::Port&);
230 bool speed_and_position (double&, framepos_t&);
234 void handle_locate (const MIDI::byte*);
236 framecnt_t resolution () const;
237 bool requires_seekahead () const { return true; }
238 framepos_t seekahead_distance() const;
239 bool give_slave_full_control_over_transport_speed() const;
244 PBD::ScopedConnectionList port_connections;
245 bool can_notify_on_unknown_rate;
248 static const int frame_tolerance;
251 framepos_t mtc_frame; /* current time */
252 framepos_t last_inbound_frame; /* when we got it; audio clocked */
253 MIDI::byte last_mtc_fps_byte;
254 framepos_t window_begin;
255 framepos_t window_end;
256 framepos_t last_mtc_timestamp;
257 framepos_t last_mtc_frame;
258 bool did_reset_tc_format;
259 TimecodeFormat saved_tc_format;
260 size_t speed_accumulator_size;
261 double* speed_accumulator;
262 size_t speed_accumulator_cnt;
263 bool have_first_speed_accumulator;
264 double average_speed;
265 Glib::Mutex reset_lock;
266 uint32_t reset_pending;
269 void reset (bool with_pos);
270 void queue_reset (bool with_pos);
273 void update_mtc_qtr (MIDI::Parser&, int, framepos_t);
274 void update_mtc_time (const MIDI::byte *, bool, framepos_t);
275 void update_mtc_status (MIDI::MTC_Status);
276 void read_current (SafeTime *) const;
277 void reset_window (framepos_t);
278 bool outside_window (framepos_t) const;
279 void process_apparent_speed (double);
282 class MIDIClock_Slave : public Slave {
284 MIDIClock_Slave (Session&, MIDI::Port&, int ppqn = 24);
286 /// Constructor for unit tests
287 MIDIClock_Slave (ISlaveSessionProxy* session_proxy = 0, int ppqn = 24);
290 void rebind (MIDI::Port&);
291 bool speed_and_position (double&, framepos_t&);
295 bool starting() const;
297 framecnt_t resolution () const;
298 bool requires_seekahead () const { return false; }
299 bool give_slave_full_control_over_transport_speed() const { return true; }
301 void set_bandwidth (double a_bandwith) { bandwidth = a_bandwith; }
304 ISlaveSessionProxy* session;
306 PBD::ScopedConnectionList port_connections;
308 /// pulses per quarter note for one MIDI clock frame (default 24)
311 /// the duration of one ppqn in frame time
312 double one_ppqn_in_frames;
314 /// the timestamp of the first MIDI clock message
315 framepos_t first_timestamp;
317 /// the time stamp and should-be transport position of the last inbound MIDI clock message
318 framepos_t last_timestamp;
319 double should_be_position;
321 /// the number of midi clock messages received (zero-based)
323 long midi_clock_count;
325 //the delay locked loop (DLL), see www.kokkinizita.net/papers/usingdll.pdf
327 /// time at the beginning of the MIDI clock frame
330 /// calculated end of the MIDI clock frame
333 /// loop error = real value - expected value
336 /// second order loop error
339 /// DLL filter bandwidth
342 /// DLL filter coefficients
346 void start (MIDI::Parser& parser, framepos_t timestamp);
347 void contineu (MIDI::Parser& parser, framepos_t timestamp);
348 void stop (MIDI::Parser& parser, framepos_t timestamp);
349 void position (MIDI::Parser& parser, MIDI::byte* message, size_t size);
350 // we can't use continue because it is a C++ keyword
351 void calculate_one_ppqn_in_frames_at(framepos_t time);
352 framepos_t calculate_song_position(uint16_t song_position_in_sixteenth_notes);
353 void calculate_filter_coefficients();
354 void update_midi_clock (MIDI::Parser& parser, framepos_t timestamp);
355 void read_current (SafeTime *) const;
356 bool stop_if_no_more_clock_events(framepos_t& pos, framepos_t now);
358 /// whether transport should be rolling
361 /// is true if the MIDI Start message has just been received until
362 /// the first MIDI Clock Event
366 class JACK_Slave : public Slave
369 JACK_Slave (jack_client_t*);
372 bool speed_and_position (double& speed, framepos_t& pos);
374 bool starting() const { return _starting; }
377 framecnt_t resolution () const { return 1; }
378 bool requires_seekahead () const { return false; }
379 void reset_client (jack_client_t* jack);
380 bool is_always_synced() const { return true; }
390 #endif /* __ardour_slave_h__ */