From 3547540f98658ed5839832aa68e6fe23098cd236 Mon Sep 17 00:00:00 2001 From: Robin Gareus Date: Tue, 10 Mar 2015 10:46:24 +0100 Subject: [PATCH] throttle TransportStateChange signal emissions --- libs/ardour/ardour/session.h | 1 + libs/ardour/session_transport.cc | 23 ++++++++++++++++++++++- 2 files changed, 23 insertions(+), 1 deletion(-) diff --git a/libs/ardour/ardour/session.h b/libs/ardour/ardour/session.h index 7d2908a18c..b50d502e16 100644 --- a/libs/ardour/ardour/session.h +++ b/libs/ardour/ardour/session.h @@ -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; diff --git a/libs/ardour/session_transport.cc b/libs/ardour/session_transport.cc index 5e01f14bdd..b392dabcbf 100644 --- a/libs/ardour/session_transport.cc +++ b/libs/ardour/session_transport.cc @@ -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; + } } }