mirror of
https://github.com/libretro/scummvm.git
synced 2024-12-13 04:28:37 +00:00
590481b12d
svn-id: r47244
251 lines
5.8 KiB
C++
251 lines
5.8 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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* $URL$
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* $Id$
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*
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*/
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#include "sound/timestamp.h"
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namespace Audio {
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static uint gcd(uint a, uint b) {
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while (a > 0) {
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int tmp = a;
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a = b % a;
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b = tmp;
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}
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return b;
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}
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Timestamp::Timestamp(uint ms, uint fr) {
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assert(fr > 0);
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_secs = ms / 1000;
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_framerateFactor = 1000 / gcd(1000, fr);
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_framerate = fr * _framerateFactor;
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// Note that _framerate is always divisible by 1000.
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_numFrames = (ms % 1000) * (_framerate / 1000);
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}
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Timestamp::Timestamp(uint s, uint frames, uint fr) {
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assert(fr > 0);
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_secs = s;
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_framerateFactor = 1000 / gcd(1000, fr);
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_framerate = fr * _framerateFactor;
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_numFrames = frames * _framerateFactor;
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normalize();
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}
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Timestamp Timestamp::convertToFramerate(uint newFramerate) const {
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Timestamp ts(*this);
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if (ts.framerate() != newFramerate) {
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ts._framerateFactor = 1000 / gcd(1000, newFramerate);
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ts._framerate = newFramerate * ts._framerateFactor;
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const uint g = gcd(_framerate, ts._framerate);
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const uint p = _framerate / g;
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const uint q = ts._framerate / g;
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// Convert the frame offset to the new framerate.
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// We round to the nearest (as opposed to always
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// rounding down), to minimize rounding errors during
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// round trip conversions.
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ts._numFrames = (ts._numFrames * q + p/2) / p;
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ts.normalize();
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}
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return ts;
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}
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void Timestamp::normalize() {
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// Convert negative _numFrames values to positive ones by adjusting _secs
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if (_numFrames < 0) {
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int secsub = 1 + (-_numFrames / _framerate);
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_numFrames += _framerate * secsub;
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_secs -= secsub;
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}
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// Wrap around if necessary
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_secs += (_numFrames / _framerate);
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_numFrames %= _framerate;
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}
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bool Timestamp::operator==(const Timestamp &ts) const {
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return cmp(ts) == 0;
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}
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bool Timestamp::operator!=(const Timestamp &ts) const {
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return cmp(ts) != 0;
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}
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bool Timestamp::operator<(const Timestamp &ts) const {
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return cmp(ts) < 0;
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}
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bool Timestamp::operator<=(const Timestamp &ts) const {
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return cmp(ts) <= 0;
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}
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bool Timestamp::operator>(const Timestamp &ts) const {
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return cmp(ts) > 0;
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}
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bool Timestamp::operator>=(const Timestamp &ts) const {
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return cmp(ts) >= 0;
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}
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int Timestamp::cmp(const Timestamp &ts) const {
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int delta = _secs - ts._secs;
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if (!delta) {
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const uint g = gcd(_framerate, ts._framerate);
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const uint p = _framerate / g;
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const uint q = ts._framerate / g;
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delta = (_numFrames * q - ts._numFrames * p);
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}
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return delta;
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}
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Timestamp Timestamp::addFrames(int frames) const {
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Timestamp ts(*this);
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// The frames are given in the original framerate, so we have to
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// adjust by _framerateFactor accordingly.
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ts._numFrames += frames * _framerateFactor;
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ts.normalize();
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return ts;
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}
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Timestamp Timestamp::addMsecs(int ms) const {
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Timestamp ts(*this);
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ts._secs += ms / 1000;
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// Add the remaining frames. Note that _framerate is always divisible by 1000.
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ts._numFrames += (ms % 1000) * (ts._framerate / 1000);
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ts.normalize();
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return ts;
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}
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void Timestamp::addIntern(const Timestamp &ts) {
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_secs += ts._secs;
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if (_framerate == ts._framerate) {
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_numFrames += ts._numFrames;
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} else {
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// We need to multiply by the quotient of the two framerates.
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// We cancel the GCD in this fraction to reduce the risk of
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// overflows.
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const uint g = gcd(_framerate, ts._framerate);
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const uint p = _framerate / g;
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const uint q = ts._framerate / g;
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_framerate *= q;
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_numFrames = _numFrames * q + ts._numFrames * p;
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}
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normalize();
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}
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Timestamp Timestamp::operator-() const {
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Timestamp result(*this);
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result._secs = -_secs;
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result._numFrames = -_numFrames;
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result.normalize();
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return result;
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}
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Timestamp Timestamp::operator+(const Timestamp &ts) const {
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Timestamp result(*this);
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result.addIntern(ts);
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return result;
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}
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Timestamp Timestamp::operator-(const Timestamp &ts) const {
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Timestamp result(*this);
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result.addIntern(-ts);
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return result;
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}
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/*
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Timestamp &Timestamp::operator+=(const Timestamp &ts) {
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addIntern(ts);
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return *this;
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}
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Timestamp &Timestamp::operator-=(const Timestamp &ts) {
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addIntern(-ts);
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return *this;
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}
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*/
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/*
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int Timestamp::frameDiff(const Timestamp &ts) const {
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return (*this - ts).totalNumberOfFrames();
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}
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*/
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int Timestamp::frameDiff(const Timestamp &ts) const {
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int delta = 0;
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if (_secs != ts._secs)
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delta = (_secs - ts._secs) * _framerate;
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delta += _numFrames;
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if (_framerate == ts._framerate) {
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delta -= ts._numFrames;
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} else {
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// We need to multiply by the quotient of the two framerates.
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// We cancel the GCD in this fraction to reduce the risk of
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// overflows.
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const uint g = gcd(_framerate, ts._framerate);
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const uint p = _framerate / g;
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const uint q = ts._framerate / g;
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delta -= ((long)ts._numFrames * p + q/2) / (long)q;
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}
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return delta / (int)_framerateFactor;
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}
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int Timestamp::msecsDiff(const Timestamp &ts) const {
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return msecs() - ts.msecs();
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}
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int Timestamp::msecs() const {
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// Note that _framerate is always divisible by 1000.
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return _secs * 1000 + _numFrames / (_framerate / 1000);
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}
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} // End of namespace Audio
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