basic work on a Tempo object that avoids (almost) all floating point arithmetic
Basic conversions between superclock and Beats are provided
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e0b5b12129
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@ -499,7 +499,7 @@ operator>>(std::istream& istr, Beats& b)
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return istr;
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}
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} // namespace Evoral
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} // namespace Temporal
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namespace PBD {
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namespace DEBUG {
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@ -21,14 +21,16 @@
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#include <stdint.h>
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namespace ARDOUR {
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#include "pbd/integer_division.h"
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namespace Temporal {
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typedef uint64_t superclock_t;
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static const superclock_t superclock_ticks_per_second = 508032000; // 2^10 * 3^4 * 5^3 * 7^2
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static inline superclock_t superclock_to_samples (superclock_t s, int sr) { return (s * sr) / superclock_ticks_per_second; }
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static inline superclock_t samples_to_superclock (int samples, int sr) { return (samples * superclock_ticks_per_second) / sr; }
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static inline superclock_t superclock_to_samples (superclock_t s, int sr) { return int_div_round (s * sr, superclock_ticks_per_second); }
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static inline superclock_t samples_to_superclock (int samples, int sr) { return int_div_round (samples * superclock_ticks_per_second, superclock_t (sr)); }
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}
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@ -0,0 +1,137 @@
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/*
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Copyright (C) 2020 Paul Davis
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef __libtemporal_tempo_h__
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#define __libtemporal_tempo_h__
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#include <cassert>
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#include <cmath>
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#include <exception>
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#include <limits>
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#include <ostream>
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#include <string>
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#include "pbd/enumwriter.h"
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#include "pbd/integer_division.h"
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#include "temporal/beats.h"
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#include "temporal/types.h"
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#include "temporal/superclock.h"
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#include "temporal/visibility.h"
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/************************* !!!! ATTENTION !!!! *************************
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NO FLOATING POINT ARITHMETIC IS ALLOWED IN THIS HEADER OR
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ANY OF THE OBJECTS DEFINED HERE.
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Exceptions:
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1) constructors/methods that accept double from the user
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2) clearly labelled methods that warn a developer to avoid
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their use or use them only for display purposes.
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************************************************************************/
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namespace Temporal {
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class TempoValue {
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private:
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/* beats per minute * big_numerator => rational number expressing (possibly fractional) bpm as superbeats-per-minute
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*
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* It is not required that big_numerator equal superclock_ticks_per_second but since the values in both cases have similar
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* desired properties (many, many factors), it doesn't hurt to use the same number.
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*/
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static const superclock_t big_numerator = superclock_ticks_per_second;
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public:
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TempoValue (double bpm) : val (bpm) {
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/* since we allow the user to provide bpm as a floating point value,
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we allow use of floating point math to determine the two critical
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integer values (superbeats-per-second and superclocks-per-beat
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*/
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_sbps = (superclock_t) round (bpm * (big_numerator / 60));
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_scpb = (superclock_t) round ((60./ bpm) * superclock_ticks_per_second);
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}
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double given_bpm_for_display_only () const { return val; }
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double actual_bpm_for_display_only () const { return (_sbps * 60) / (double) big_numerator; }
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uint64_t ticks_per_second() const { return int_div_round ((_sbps * Temporal::ticks_per_beat), big_numerator); }
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superclock_t superclocks_per_beat() const { return _scpb; }
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Temporal::Beats superclocks_as_beats (superclock_t sc) const {
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/* convert sc into superbeats, given that sc represents some number of seconds */
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const superclock_t whole_seconds = sc / superclock_ticks_per_second;
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const superclock_t remainder = sc - (whole_seconds * superclock_ticks_per_second);
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const superclock_t superbeats = (_sbps * whole_seconds) + int_div_round ((_sbps * remainder), superclock_ticks_per_second);
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/* convert superbeats to beats:ticks */
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uint32_t b = superbeats / big_numerator;
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const uint64_t remain = superbeats - (b * big_numerator);
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uint32_t t = int_div_round ((Temporal::ticks_per_beat * remain), big_numerator);
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return Beats (b, t);
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}
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superclock_t beats_as_superclocks (Temporal::Beats const & b) const {
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/* no symmetrical with superclocks_as_beats() because Beats already breaks apart the beats:ticks,
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with the ticks value denominated by Temporal::ticks_per_beat
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*/
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return (_scpb * b.get_beats()) + int_div_round ((_scpb * b.get_ticks()), superclock_t (Temporal::ticks_per_beat));
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}
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Temporal::Beats seconds_as_beats (uint64_t num, uint64_t denom) const {
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return superclocks_as_beats ((num * superclock_ticks_per_second) / denom);
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}
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double beats_as_float_seconds_avoid_me (Temporal::Beats const & b) const {
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return beats_as_superclocks (b) / (double) superclock_ticks_per_second;
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}
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private:
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double val; /* as given to constructor */
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uint64_t _sbps; /* superbeats-per-second */
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superclock_t _scpb; /* superclocks-per-beat */
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};
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inline std::ostream&
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operator<<(std::ostream& os, const TempoValue& v)
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{
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os << v.actual_bpm_for_display_only ();
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return os;
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}
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inline std::istream&
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operator>>(std::istream& istr, TempoValue& v)
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{
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#if 0
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uint16_t w;
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uint64_t f;
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char d; /* delimiter, whatever it is */
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istr >> w >> d >> f;
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v = TempoValue (w, f);
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#endif
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return istr;
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}
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} /* namespace Temporal */
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#endif /* __libtemporal_tempo_h__ */
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@ -0,0 +1,128 @@
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/* COMPILE: c++ -o test -I../pbd -I. test.cc */
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#include <iostream>
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#include <iomanip>
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#include "temporal/tempo.h"
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using namespace std;
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using namespace Temporal;
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int
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main (int argc, char* argv[])
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{
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double bpm;
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if (argc < 2) {
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cerr << "Usage: " << argv[0] << " BPM\n";
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return -1;
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}
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if (sscanf (argv[1], "%lf", &bpm) != 1) {
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cerr << "Cannot parse " << argv[1] << " as floating point value\n";
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return -2;
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}
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TempoValue tempo (bpm);
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uint64_t numerator_seconds = 1;
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uint64_t denominator_seconds = 2;
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Temporal::Beats fb = tempo.seconds_as_beats (numerator_seconds, denominator_seconds);
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/* compute 20 minutes of beats:ticks */
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Temporal::Beats b20 = tempo.seconds_as_beats ((20 * 60), 1);
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double d20 = 20.0 * bpm;
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double d20r = 20.0 * tempo.actual_bpm_for_display_only ();
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cout << "bpm " << setprecision (12) << bpm << " => " << tempo << " ticks/second = " << tempo.ticks_per_second ()
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<< " tps " << tempo.ticks_per_second ()
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<< " bpm " << tempo.actual_bpm_for_display_only ()
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<< ' ' << numerator_seconds << '/' << denominator_seconds << " sec = " << fb
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<< " 20 mins = " << b20
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<< " 20 mins " << d20 << " computed " << d20r
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<< " b-as-sc " << tempo.beats_as_superclocks (Beats (1,0))
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<< " scpb " << tempo.superclocks_per_beat ()
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<< endl;
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for (uint32_t tn = 0; tn < Temporal::ticks_per_beat; ++tn) {
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Temporal::Beats b (1, tn);
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double sec = tempo.beats_as_float_seconds_avoid_me (b);
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double csec = (60. / bpm) * (1 + (tn / 1920.));
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if (fabs (sec - csec) > 0.00000001) {
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cout << b << " sec " << sec << " csec " << csec << " err " << sec - csec << endl;
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}
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}
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int rate[] = { 16000, 22050, 24000, 32000, 33075, 44100, 48000, 88200, 96000, 0 };
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for (int s = 0; rate[s] != 0; ++s) {
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cout << "Checking with SR = " << rate[s] << endl;
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double tempos[] = {
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1,
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10,
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30,
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60,
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120,
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240,
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1200,
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33,
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47,
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91 + 4./7,
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100./3.,
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100./7.,
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100./5.,
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100./9.,
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M_PI,
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M_PI * 20.,
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0.
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};
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for (int t = 0; tempos[t] != 0; ++t) {
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tempo = TempoValue (tempos[t]);
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cout << "\tChecking tempo " << tempo.given_bpm_for_display_only () << endl;
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for (uint32_t tn = 0; tn < Temporal::ticks_per_beat; ++tn) {
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Temporal::Beats b (1, tn);
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superclock_t sc = tempo.beats_as_superclocks (b);
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Temporal::Beats b2 = tempo.superclocks_as_beats (sc);
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if (b2 != b) {
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cout << "\t\tb2 " << b2 << " != b " << b << endl;
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}
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uint64_t samples = superclock_to_samples (sc, rate[s]);
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superclock_t sc2 = samples_to_superclock (samples, rate[s]);
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Temporal::Beats b3 = tempo.superclocks_as_beats (sc2);
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if (b3 != b) {
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cout << "\t\tb3 " << b3 << " != b " << b << endl;
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break;
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}
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}
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cout << "Now checking sample positions\n";
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for (int p = 0; p < rate[s]; ++p) {
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superclock_t sc = samples_to_superclock (p, rate[s]);
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Temporal::Beats b = tempo.superclocks_as_beats (sc);
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superclock_t sc2 = tempo.beats_as_superclocks (b);
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uint64_t sm = superclock_to_samples (sc2, rate[s]);
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if (p != sm) {
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cout << "\t\tsm " << sm << " != " << p << endl;
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break;
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}
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}
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}
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}
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return 0;
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}
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