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* fix concerning a comment on issue 2541: Go back to the last MIDI beat on stop

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git-svn-id: svn://localhost/ardour2/branches/3.0@4548 d708f5d6-7413-0410-9779-e7cbd77b26cf
This commit is contained in:
Hans Baier 2009-02-14 07:18:38 +00:00
parent ef172d7ad6
commit 90ee153fc1
2 changed files with 23 additions and 6 deletions
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4
libs/ardour/ardour/slave.h
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@ -244,6 +244,10 @@ class MIDIClock_Slave : public Slave, public sigc::trackable {
nframes_t last_timestamp;
double should_be_position;
/// the number of midi clock messages received (zero-based)
/// since start
long midi_clock_count;
//the delay locked loop (DLL), see www.kokkinizita.net/papers/usingdll.pdf
/// time at the beginning of the MIDI clock frame

25
libs/ardour/midi_clock_slave.cc
View File

@ -119,16 +119,15 @@ MIDIClock_Slave::update_midi_clock (Parser& parser, nframes_t timestamp)
if ( (!_starting) && (!_started) ) {
return;
}
// the number of midi clock messages (zero-based)
static long midi_clock_count;
calculate_one_ppqn_in_frames_at(should_be_position);
nframes_t elapsed_since_start = timestamp - first_timestamp;
double error = 0;
if (_starting || last_timestamp == 0) {
if (_starting || last_timestamp == 0) {
midi_clock_count = 0;
first_timestamp = timestamp;
elapsed_since_start = should_be_position;
@ -237,7 +236,21 @@ MIDIClock_Slave::stop (Parser& parser, nframes_t timestamp)
_started = false;
// locate to last MIDI clock position
session.request_transport_speed(0.0);
session.request_locate(should_be_position, false);
// we need to go back to the last MIDI beat (6 ppqn)
// and lets hope the tempo didnt change in the meantime :)
// begin at the should be position, because
// that is the position of the last MIDI Clock
// message and that is probably what the master
// expects where we are right now
nframes_t stop_position = should_be_position;
// find out the last MIDI beat: go back #midi_clocks mod 6
// and lets hope the tempo didnt change in those last 6 beats :)
stop_position -= (midi_clock_count % 6) * one_ppqn_in_frames;
session.request_locate(stop_position, false);
last_timestamp = 0;
}
}