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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* 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 General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $URL$
* $Id$
*
*/
#ifndef SOUND_TIMESTAMP_H
#define SOUND_TIMESTAMP_H
#include "common/scummsys.h"
namespace Audio {
/**
* Timestamps allow measuring times with a sub-millisecond granularity,
* and without rounding losses. This is achieved by measuring frames
* instead of milliseconds: Specify an initial time in milliseconds
* plus framerate (in frames per second).
*/
class Timestamp {
protected:
/**
* The millisecond part of this timestamp.
* The total time represented by this timestamp is
* computed as follows:
* _msecs + 1000 * _numberOfFrames / _framerate
*/
uint _msecs;
/**
* The number of frames which together with _msecs encodes
* the timestamp. The total number of frames represented
* by this timestamp is computed as follows:
* _numberOfFrames + _msecs * _framerate / 1000
*/
int _numberOfFrames;
/** The framerate, i.e. the number of frames per second. */
int _framerate;
public:
/**
* Set up a timestamp with a given time and framerate.
* @param msecs starting time in milliseconds
* @param framerate number of frames per second (must be > 0)
*/
Timestamp(uint32 msecs, int framerate);
/**
* Return a timestamp which represents as closely as possible
* the point in time describes by this timestamp, but with
* a different framerate.
*/
Timestamp convertToFramerate(int newFramerate) const;
bool operator==(const Timestamp &ts) const;
bool operator!=(const Timestamp &ts) const;
// bool operator<(const Timestamp &ts) const;
// bool operator<=(const Timestamp &ts) const;
// bool operator>(const Timestamp &ts) const;
// bool operator>=(const Timestamp &ts) const;
/**
* Returns a new timestamp, which corresponds to the time encoded
* by this timestamp with the given number of frames added.
*/
Timestamp addFrames(int frames) const;
/**
* Returns a new timestamp, which corresponds to the time encoded
* by this timestamp with the given number of milliseconds added.
*/
Timestamp addMsecs(int ms) const;
/**
* Computes the number of frames between this timestamp and ts.
* The frames are with respect to the framerate used by this
* Timestamp (which may differ from the framerate used by ts).
*/
int frameDiff(const Timestamp &ts) const;
/** Computes the number off milliseconds between this timestamp and ts. */
int msecsDiff(const Timestamp &ts) const;
/**
* Determines the time in milliseconds described by this timestamp,
* rounded down.
*/
uint32 msecs() const;
/** Return the framerate used by this timestamp. */
int getFramerate() const { return _framerate; }
};
} // End of namespace Audio
#endif
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