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 class Slave can be used to sync ardours tempo to an external source
43 * like MTC, MIDI Clock, etc.
45 * The name of the class may be a bit misleading: A subclass of Slave actually
46 * acts as a master for Ardour, that means Ardour will try to follow the
47 * speed and transport position of the implementation of Slave.
48 * Therefor 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.
99 * (Otherwise Session:average_slave_delta will become negative, and
100 * the transport will move silently)
102 * <li>Slave::locked() should return true, otherwise Session::no_roll will be called</li>
103 * <li>Slave::starting() should be false, otherwise the transport will not move until it becomes true</li> *
106 * @param speed - The transport speed requested
107 * @param position - The transport position requested
109 virtual bool speed_and_position (float& speed, nframes_t& position) = 0;
112 * reports to ardour whether the Slave is currently synced to its external
115 * @return - when returning false, the transport will stop rolling
117 virtual bool locked() const = 0;
120 * reports to ardour whether the slave is in a sane state
122 * @return - when returning false, the transport will be stopped and the slave
123 * disconnected from ardour.
125 virtual bool ok() const = 0;
128 * reports to ardour whether the slave is in the process of starting
131 * @return - when returning false, transport will not move until this method returns true
133 virtual bool starting() const { return false; }
136 * @return - the timing resolution of the Slave - If the distance of ardours transport
137 * to the slave becomes negative or greater than the resolution, sound will stop
138 * (Session::follow_slave label silent_motion)
140 virtual nframes_t resolution() const = 0;
143 * @return - when returning true, ardour will wait for one second before transport
146 virtual bool requires_seekahead () const = 0;
149 * @return - when returning true, ardour will use transport speed 1.0 no matter what
152 virtual bool is_always_synced() const { return false; }
168 class MTC_Slave : public Slave, public sigc::trackable {
170 MTC_Slave (Session&, MIDI::Port&);
173 void rebind (MIDI::Port&);
174 bool speed_and_position (float&, nframes_t&);
178 void handle_locate (const MIDI::byte*);
180 nframes_t resolution() const;
181 bool requires_seekahead () const { return true; }
186 std::vector<sigc::connection> connections;
187 bool can_notify_on_unknown_rate;
190 nframes_t mtc_frame; /* current time */
191 nframes_t last_inbound_frame; /* when we got it; audio clocked */
194 nframes_t first_mtc_frame;
195 nframes_t first_mtc_time;
197 static const int32_t accumulator_size = 128;
198 float accumulator[accumulator_size];
199 int32_t accumulator_index;
200 bool have_first_accumulated_speed;
203 void update_mtc_qtr (MIDI::Parser&);
204 void update_mtc_time (const MIDI::byte *, bool);
205 void update_mtc_status (MIDI::Parser::MTC_Status);
206 void read_current (SafeTime *) const;
209 class MIDIClock_Slave : public Slave, public sigc::trackable {
211 MIDIClock_Slave (Session&, MIDI::Port&, int ppqn = 24);
214 void rebind (MIDI::Port&);
215 bool speed_and_position (float&, nframes_t&);
219 bool starting() const { return false; }
221 nframes_t resolution() const;
222 bool requires_seekahead () const { return false; }
227 std::vector<sigc::connection> connections;
229 /// pulses per quarter note for one MIDI clock frame (default 24)
232 /// the duration of one ppqn in frame time
233 double one_ppqn_in_frames;
235 /// the time stamp and transport position of the last inbound MIDI clock message
238 /// The duration of the current MIDI clock frame in frames
239 nframes_t current_midi_clock_frame_duration;
240 /// the timestamp of the last inbound MIDI clock message
241 nframes_t last_inbound_frame;
243 /// how many MIDI clock frames to average over
244 static const int32_t accumulator_size = 4;
245 float accumulator[accumulator_size];
246 int32_t accumulator_index;
248 /// the running average of current_midi_clock_frame_duration
249 float average_midi_clock_frame_duration;
252 void start (MIDI::Parser& parser, nframes_t timestamp);
253 void stop (MIDI::Parser& parser, nframes_t timestamp);
254 void update_midi_clock (MIDI::Parser& parser, nframes_t timestamp);
255 void read_current (SafeTime *) const;
257 /// whether transport should be rolling
260 /// is true if the MIDI Start message has just been received until
261 /// the first call of speed_and_position(...)
265 class ADAT_Slave : public Slave
271 bool speed_and_position (float& speed, nframes_t& pos) {
277 bool locked() const { return false; }
278 bool ok() const { return false; }
279 nframes_t resolution() const { return 1; }
280 bool requires_seekahead () const { return true; }
283 class JACK_Slave : public Slave
286 JACK_Slave (jack_client_t*);
289 bool speed_and_position (float& speed, nframes_t& pos);
291 bool starting() const { return _starting; }
294 nframes_t resolution() const { return 1; }
295 bool requires_seekahead () const { return false; }
296 void reset_client (jack_client_t* jack);
297 bool is_always_synced() const { return true; }
307 #endif /* __ardour_slave_h__ */