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 <jack/jack.h>
27 #include <sigc++/signal.h>
28 #include <ardour/ardour.h>
29 #include <midi++/parser.h>
30 #include <midi++/types.h>
42 * @brief The Slave interface can be used to sync ARDOURs tempo to an external source
43 * like MTC, MIDI Clock, etc.
45 * The name of the interface may be a bit misleading: A subclass of Slave actually
46 * acts as a time master for ARDOUR, that means ARDOUR will try to follow the
47 * speed and transport position of the implementation of Slave.
48 * Therefore it is rather that class, that makes ARDOUR a slave by connecting it
49 * to its external time master.
57 * This is the most important function to implement:
58 * Each process cycle, Session::follow_slave will call this method.
59 * and after the method call they should
61 * Session::follow_slave will then try to follow the given
62 * <emph>position</emph> using a delay locked loop (DLL),
63 * starting with the first given transport speed.
64 * If the values of speed and position contradict each other,
65 * ARDOUR will always follow the position and disregard the speed.
66 * Although, a correct speed is important so that ARDOUR
67 * can sync to the master time source quickly.
69 * For background information on delay locked loops,
70 * see http://www.kokkinizita.net/papers/usingdll.pdf
72 * The method has the following precondition:
75 * Slave::ok() should return true, otherwise playback will stop
76 * immediately and the method will not be called
79 * when the references speed and position are passed into the Slave
80 * they are uninitialized
84 * After the method call the following postconditions should be met:
87 * The first position value on transport start should be 0,
88 * otherwise ARDOUR will try to locate to the new position
89 * rather than move to it
92 * the references speed and position should be assigned
93 * to the Slaves current requested transport speed
94 * and transport position.
97 * Slave::resolution() should be greater than the maximum distance of
98 * ARDOURs transport position to the slaves requested transport position.
100 * <li>Slave::locked() should return true, otherwise Session::no_roll will be called</li>
101 * <li>Slave::starting() should be false, otherwise the transport will not move until it becomes true</li> *
104 * @param speed - The transport speed requested
105 * @param position - The transport position requested
107 virtual bool speed_and_position (float& speed, nframes_t& position) = 0;
110 * reports to ARDOUR whether the Slave is currently synced to its external
113 * @return - when returning false, the transport will stop rolling
115 virtual bool locked() const = 0;
118 * reports to ARDOUR whether the slave is in a sane state
120 * @return - when returning false, the transport will be stopped and the slave
121 * disconnected from ARDOUR.
123 virtual bool ok() const = 0;
126 * reports to ARDOUR whether the slave is in the process of starting
129 * @return - when returning false, transport will not move until this method returns true
131 virtual bool starting() const { return false; }
134 * @return - the timing resolution of the Slave - If the distance of ARDOURs transport
135 * to the slave becomes greater than the resolution, sound will stop
137 virtual nframes_t resolution() const = 0;
140 * @return - when returning true, ARDOUR will wait for one second before transport
143 virtual bool requires_seekahead () const = 0;
146 * @return - when returning true, ARDOUR will use transport speed 1.0 no matter what
149 virtual bool is_always_synced() const { return false; }
165 class MTC_Slave : public Slave, public sigc::trackable {
167 MTC_Slave (Session&, MIDI::Port&);
170 void rebind (MIDI::Port&);
171 bool speed_and_position (float&, nframes_t&);
175 void handle_locate (const MIDI::byte*);
177 nframes_t resolution() const;
178 bool requires_seekahead () const { return true; }
183 std::vector<sigc::connection> connections;
184 bool can_notify_on_unknown_rate;
187 nframes_t mtc_frame; /* current time */
188 nframes_t last_inbound_frame; /* when we got it; audio clocked */
189 MIDI::byte last_mtc_fps_byte;
192 nframes_t first_mtc_frame;
193 nframes_t first_mtc_time;
195 static const int32_t accumulator_size = 128;
196 float accumulator[accumulator_size];
197 int32_t accumulator_index;
198 bool have_first_accumulated_speed;
201 void update_mtc_qtr (MIDI::Parser&);
202 void update_mtc_time (const MIDI::byte *, bool);
203 void update_mtc_status (MIDI::Parser::MTC_Status);
204 void read_current (SafeTime *) const;
207 class MIDIClock_Slave : public Slave, public sigc::trackable {
209 MIDIClock_Slave (Session&, MIDI::Port&, int ppqn = 24);
212 void rebind (MIDI::Port&);
213 bool speed_and_position (float&, nframes_t&);
217 bool starting() const;
219 nframes_t resolution() const;
220 bool requires_seekahead () const { return false; }
225 std::vector<sigc::connection> connections;
227 /// pulses per quarter note for one MIDI clock frame (default 24)
230 /// the duration of one ppqn in frame time
231 double one_ppqn_in_frames;
233 /// the time stamp and transport position of the last inbound MIDI clock message
235 /// since current.position is integral, we need to keep track of decimal places
237 double current_position;
239 /// The duration of the current MIDI clock frame in frames
240 nframes_t current_midi_clock_frame_duration;
241 /// the timestamp of the last inbound MIDI clock message
242 nframes_t last_inbound_frame;
244 /// how many MIDI clock frames to average over
245 static const int32_t accumulator_size = 4;
246 double accumulator[accumulator_size];
247 int32_t accumulator_index;
249 /// the running average of current_midi_clock_frame_duration
250 double average_midi_clock_frame_duration;
253 void start (MIDI::Parser& parser, nframes_t timestamp);
254 void stop (MIDI::Parser& parser, nframes_t timestamp);
255 // we can't use continue because it is a C++ keyword
256 void contineu (MIDI::Parser& parser, nframes_t timestamp);
257 void calculate_one_ppqn_in_frames_at(nframes_t time);
258 void update_midi_clock (MIDI::Parser& parser, nframes_t timestamp);
259 void read_current (SafeTime *) const;
260 bool stop_if_no_more_clock_events(nframes_t& pos, nframes_t now, SafeTime& last);
262 /// whether transport should be rolling
265 /// is true if the MIDI Start message has just been received until
266 /// the first MIDI Clock Event
270 class ADAT_Slave : public Slave
276 bool speed_and_position (float& speed, nframes_t& pos) {
282 bool locked() const { return false; }
283 bool ok() const { return false; }
284 nframes_t resolution() const { return 1; }
285 bool requires_seekahead () const { return true; }
288 class JACK_Slave : public Slave
291 JACK_Slave (jack_client_t*);
294 bool speed_and_position (float& speed, nframes_t& pos);
296 bool starting() const { return _starting; }
299 nframes_t resolution() const { return 1; }
300 bool requires_seekahead () const { return false; }
301 void reset_client (jack_client_t* jack);
302 bool is_always_synced() const { return true; }
312 #endif /* __ardour_slave_h__ */