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throttle TransportStateChange signal emissions

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This commit is contained in:
Robin Gareus 2015-03-10 10:46:24 +01:00
parent 2e82aa2743
commit 3547540f98
2 changed files with 23 additions and 1 deletions
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1
libs/ardour/ardour/session.h
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@ -992,6 +992,7 @@ class LIBARDOUR_API Session : public PBD::StatefulDestructible, public PBD::Scop
double _transport_speed;
double _default_transport_speed;
double _last_transport_speed;
double _signalled_varispeed;
double _target_transport_speed;
CubicInterpolation interpolation;

23
libs/ardour/session_transport.cc
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@ -1321,7 +1321,28 @@ Session::set_transport_speed (double speed, framepos_t destination_frame, bool a
}
DEBUG_TRACE (DEBUG::Transport, string_compose ("send TSC3 with speed = %1\n", _transport_speed));
TransportStateChange (); /* EMIT SIGNAL */
/* throttle signal emissions.
* when slaved [_last]_transport_speed
* usually changes every cycle (tiny amounts due to DLL).
* Emitting a signal every cycle is overkill and unwarranted.
*
* Using _last_transport_speed is not acceptable,
* since it allows for large changes over a long period
* of time. Hence we introduce a dedicated variable to keep track
*
* The 0.2% dead-zone is somewhat arbitrary. Main use-case
* for TransportStateChange() here is the ShuttleControl display.
*/
if (fabsf(_signalled_varispeed - speed) > .002f
// still, signal hard changes to 1.0 and 0.0:
|| ( speed == 1.f && _signalled_varispeed != 1.f)
|| ( speed == 0.f && _signalled_varispeed != 0.f)
)
{
TransportStateChange (); /* EMIT SIGNAL */
_signalled_varispeed = speed;
}
}
}