JackFrameTimer.cpp
/*
Copyright (C) 2001 Paul Davis
Copyright (C) 2004-2008 Grame
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include "JackFrameTimer.h"
#include "JackError.h"
#include <math.h>
#include <stdio.h>
namespace Jack
{
#if defined(WIN32) && !defined(__MINGW32__)
/* missing on Windows : see http://bugs.mysql.com/bug.php?id=15936 */
inline double rint(double nr)
{
double f = floor(nr);
double c = ceil(nr);
return (((c -nr) >= (nr - f)) ? f : c);
}
#endif
JackTimer::JackTimer()
{
fInitialized = false;
fFrames = 0;
fCurrentWakeup = 0;
fCurrentCallback = 0;
fNextWakeUp = 0;
fPeriodUsecs = 0.0f;
fFilterOmega = 0.0f; /* Initialised later */
}
jack_nframes_t JackTimer::Time2Frames(jack_time_t usecs, jack_nframes_t buffer_size)
{
if (fInitialized) {
/*
Make sure we have signed differences. It would make a lot of sense
to use the standard signed intNN_t types everywhere instead of e.g.
jack_nframes_t and jack_time_t. This would at least ensure that the
types used below are the correct ones. There is no way to get a type
that would be 'a signed version of jack_time_t' for example - the
types below are inherently fragile and there is no automatic way to
check they are the correct ones. The only way is to check manually
against jack/types.h. FA - 16/02/2012
*/
int64_t du = usecs - fCurrentWakeup;
int64_t dp = fNextWakeUp - fCurrentWakeup;
return fFrames + (int32_t)rint((double)du / (double)dp * buffer_size);
} else {
return 0;
}
}
jack_time_t JackTimer::Frames2Time(jack_nframes_t frames, jack_nframes_t buffer_size)
{
if (fInitialized) {
/*
Make sure we have signed differences. It would make a lot of sense
to use the standard signed intNN_t types everywhere instead of e.g.
jack_nframes_t and jack_time_t. This would at least ensure that the
types used below are the correct ones. There is no way to get a type
that would be 'a signed version of jack_time_t' for example - the
types below are inherently fragile and there is no automatic way to
check they are the correct ones. The only way is to check manually
against jack/types.h. FA - 16/02/2012
*/
int32_t df = frames - fFrames;
int64_t dp = fNextWakeUp - fCurrentWakeup;
return fCurrentWakeup + (int64_t)rint((double) df * (double) dp / buffer_size);
} else {
return 0;
}
}
int JackTimer::GetCycleTimes(jack_nframes_t* current_frames, jack_time_t* current_usecs, jack_time_t* next_usecs, float* period_usecs)
{
if (fInitialized) {
*current_frames = fFrames;
*current_usecs = fCurrentWakeup;
*next_usecs = fNextWakeUp;
*period_usecs = fPeriodUsecs;
return 0;
} else {
return -1;
}
}
jack_nframes_t JackTimer::FramesSinceCycleStart(jack_time_t cur_time, jack_nframes_t frames_rate)
{
return (jack_nframes_t) floor((((float)frames_rate) / 1000000.0f) * (cur_time - fCurrentCallback));
}
void JackFrameTimer::InitFrameTime()
{
fFirstWakeUp = true;
}
void JackFrameTimer::IncFrameTime(jack_nframes_t buffer_size, jack_time_t callback_usecs, jack_time_t period_usecs)
{
if (fFirstWakeUp) {
InitFrameTimeAux(callback_usecs, period_usecs);
fFirstWakeUp = false;
}
IncFrameTimeAux(buffer_size, callback_usecs, period_usecs);
}
void JackFrameTimer::ResetFrameTime(jack_time_t callback_usecs)
{
if (!fFirstWakeUp) { // ResetFrameTime may be called by a xrun/delayed wakeup on the first cycle
JackTimer* timer = WriteNextStateStart();
timer->fCurrentWakeup = callback_usecs;
timer->fCurrentCallback = callback_usecs;
WriteNextStateStop();
TrySwitchState(); // always succeed since there is only one writer
}
}
/*
Use the state returned by ReadCurrentState and check that the state was not changed during the read operation.
The operation is lock-free since there is no intermediate state in the write operation that could cause the
read to loop forever.
*/
void JackFrameTimer::ReadFrameTime(JackTimer* timer)
{
UInt16 next_index = GetCurrentIndex();
UInt16 cur_index;
do {
cur_index = next_index;
memcpy(timer, ReadCurrentState(), sizeof(JackTimer));
next_index = GetCurrentIndex();
} while (cur_index != next_index); // Until a coherent state has been read
}
// Internal
void JackFrameTimer::InitFrameTimeAux(jack_time_t callback_usecs, jack_time_t period_usecs)
{
/* the first wakeup or post-freewheeling or post-xrun */
/* There seems to be no significant difference between
the two conditions OR-ed above. Incrementing the
frame_time after an xrun shouldn't harm, as there
will be a discontinuity anyway. So the two are
combined in this version.
FA 16/03/2012
*/
/* Since the DLL *will* be run, next_wakeup should be the
current wakeup time *without* adding the period time, as
if it were computed in the previous period.
FA 16/03/2012
*/
/* Added initialisation of timer->period_usecs, required
due to the modified implementation of the DLL itself.
OTOH, this should maybe not be repeated after e.g.
freewheeling or an xrun, as the current value would be
more accurate than the nominal one. But it doesn't really
harm either. Implementing this would require a new flag
in the engine structure, to be used after freewheeling
or an xrun instead of first_wakeup. I don't know if this
can be done without breaking compatibility, so I did not
add this
FA 13/02/2012
*/
/* Added initialisation of timer->filter_omega. This makes
the DLL bandwidth independent of the actual period time.
The bandwidth is now 1/8 Hz in all cases. The value of
timer->filter_omega is 2 * pi * BW * Tperiod.
FA 13/02/2012
*/
JackTimer* timer = WriteNextStateStart();
timer->fPeriodUsecs = (float)period_usecs;
timer->fCurrentCallback = callback_usecs;
timer->fNextWakeUp = callback_usecs;
timer->fFilterOmega = period_usecs * 7.854e-7f;
WriteNextStateStop();
TrySwitchState(); // always succeed since there is only one writer
}
void JackFrameTimer::IncFrameTimeAux(jack_nframes_t buffer_size, jack_time_t callback_usecs, jack_time_t period_usecs)
{
JackTimer* timer = WriteNextStateStart();
/* Modified implementation (the actual result is the same).
'fSecondOrderIntegrator' is renamed to 'fPeriodUsecs'
and now represents the DLL's best estimate of the
period time in microseconds (before it was a scaled
version of the difference w.r.t. the nominal value).
This allows this value to be made available to clients
that are interested in it (see jack_get_cycle_times).
This change also means that 'fPeriodUsecs' must be
initialised to the nominal period time instead of zero.
This is done in the first cycle in jack_run_cycle().
'fFilterCoefficient' is renamed to 'fFilterOmega'. It
is now equal to the 'omega' value as defined in the
'Using a DLL to filter time' paper (before it was a
scaled version of this value). It is computed once in
jack_run_cycle() rather than set to a fixed value. This
makes the DLL bandwidth independent of the period time.
FA 13/02/2012
*/
float delta = (float)((int64_t)callback_usecs - (int64_t)timer->fNextWakeUp);
delta *= timer->fFilterOmega;
timer->fCurrentWakeup = timer->fNextWakeUp;
timer->fCurrentCallback = callback_usecs;
timer->fFrames += buffer_size;
timer->fPeriodUsecs += timer->fFilterOmega * delta;
timer->fNextWakeUp += (int64_t)floorf(timer->fPeriodUsecs + 1.41f * delta + 0.5f);
timer->fInitialized = true;
WriteNextStateStop();
TrySwitchState(); // always succeed since there is only one writer
}
} // end of namespace
Jack
Definition: JackAC3Encoder.cpp:30