sound/timestamp.h

   1 /* ScummVM - Graphic Adventure Engine
   2  *
   3  * ScummVM is the legal property of its developers, whose names
   4  * are too numerous to list here. Please refer to the COPYRIGHT
   5  * file distributed with this source distribution.
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * as published by the Free Software Foundation; either version 2
  10  * of the License, or (at your option) any later version.
  11
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  20  *
  21  * $URL$
  22  * $Id$
  23  *
  24  */
  25
  26 #ifndef SOUND_TIMESTAMP_H
  27 #define SOUND_TIMESTAMP_H
  28
  29 #include "common/scummsys.h"
  30
  31 namespace Audio {
  32
  33 /**
  34  * Timestamps allow measuring times with a sub-millisecond granularity,
  35  * and without rounding losses. This is achieved by measuring frames
  36  * instead of milliseconds: Specify an initial time in milliseconds
  37  * plus framerate (in frames per second).
  38  */
  39 class Timestamp {
  40 protected:
  41         uint32 _msecs;
  42         int _frameRate;
  43         int _frameOffset;
  44         /* Total time: msecs + frame_offset/frame_rate */
  45
  46 public:
  47         Timestamp();
  48
  49         /**
  50          * Set up a timestamp with a given time and framerate.
  51          * @param msecs         staring time in milliseconds
  52          * @param frameRate     number of frames per second
  53          */
  54         Timestamp(uint32 msecs, int frameRate);
  55
  56         /** Adds a number of frames to a timestamp. */
  57         Timestamp addFrames(int frames) const;
  58
  59         /** Adds a number of milliseconds to a timestamp. */
  60         Timestamp addMsecs(int ms) const;
  61
  62         /** Computes the difference (# of frames) between this timestamp and b. */
  63         int frameDiff(const Timestamp &b) const;
  64
  65         /** Computes the difference (# of milliseconds) between this timestamp and b. */
  66         int msecsDiff(const Timestamp &b) const;
  67
  68         /** Determines the time in milliseconds described by this timestamp. */
  69         uint32 msecs() const;
  70 };
  71
  72
  73 } // End of namespace Audio
  74
  75 #endif