ardour/livetrax
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fix logic error when deciding whether we are actually changing speeds

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This commit is contained in:
Paul Davis 2021-02-12 11:42:39 -07:00
parent 8e7a23642c
commit 5c4ed8ee2b
1 changed files with 16 additions and 2 deletions
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18
libs/ardour/session_transport.cc
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@ -360,7 +360,21 @@ Session::set_transport_speed (double speed, bool abort, bool clear_state, bool a
DEBUG_TRACE (DEBUG::Transport, string_compose ("@ %5 Set transport speed to %1 from %4 (es = %7) (def %8), abort = %2 clear_state = %3, as_default %6\n",
speed, abort, clear_state, _transport_speed, _transport_sample, as_default, _engine_speed, _default_transport_speed));
if ((_engine_speed != 1) && (_engine_speed == fabs (speed)) && (speed * _transport_speed) >= 0) {
/* the logic:
a) engine speed is not 1.0 (normal speed)
b) engine speed matches the requested speed (sign ignored)
c) speed and transport speed have the same sign (no direction change)
For (c) the correct arithmetical test is >= 0, but we care about the
case where at least one of them is zero. That would generate an
equality with zero, but if only one of them is zero, we still need
to change speed. So we check that the product is > 0, which implies
that neither of them are zero, and they have the same sign.
*/
if ((_engine_speed != 1) && (_engine_speed == fabs (speed)) && ((speed * _transport_speed) > 0)) {
/* engine speed is not changing and no direction change, do nothing */
DEBUG_TRACE (DEBUG::Transport, "no reason to change speed, do nothing\n");
return;
@ -381,7 +395,7 @@ Session::set_transport_speed (double speed, bool abort, bool clear_state, bool a
if (speed != 0) {
new_engine_speed = fabs (speed);
_requested_transport_speed = speed;
if (speed < 0) speed = -1;
if (speed < 0) speed = -1;
if (speed > 0) speed = 1;
}