libsound/SoundUtils.h

   1 // SoundUtils.h     Utilities for handling sound data.
   2 //
   3 //   Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012
   4 //   Free Software Foundation, Inc
   5 //
   6 // This program is free software; you can redistribute it and/or modify
   7 // it under the terms of the GNU General Public License as published by
   8 // the Free Software Foundation; either version 3 of the License, or
   9 // (at your option) any later version.
  10 //
  11 // This program is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15 //
  16 // You should have received a copy of the GNU General Public License
  17 // along with this program; if not, write to the Free Software
  18 // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  19
  20 #ifndef GNASH_SOUND_UTILS_H
  21 #define GNASH_SOUND_UTILS_H
  22
  23 #include <algorithm>
  24 #include <functional>
  25 #include <cstdint>
  26
  27 #include "SoundInfo.h"
  28
  29 namespace gnash {
  30 namespace sound {
  31
  32 /// Volume adjustment
  33 //
  34 /// @param start        The beginning of the range to adjust volume for
  35 /// @param end         The end of the range to adjust volume for
  36 /// @param volume       Volume factor
  37 template<typename T>
  38 inline void
  39 adjustVolume(T* start, T* end, float volume)
  40 {
  41     std::transform(start, end, start,
  42         [volume](const T& volsource) { return volume * volsource; });
  43 }
  44
  45 /// Convert SWF-specified number of samples to output number of samples
  46 //
  47 /// SWF-specified number of samples are: delaySeek in DEFINESOUND,
  48 /// latency in STREAMSOUNDHEAD and seekSamples in STREAMSOUNDBLOCK.
  49 /// These refer to samples at the sampleRate of input.
  50 ///
  51 /// As gnash will resample the sounds to match expected output
  52 /// (44100 Hz, stereo 16bit) this function is handy to convert
  53 /// for simpler use later.
  54 inline size_t
  55 swfToOutSamples(const media::SoundInfo& sinfo, size_t swfSamples,
  56         const size_t outRate = 44100)
  57 {
  58     // NOTE: this was tested with inputs:
  59     //     - isStereo?0 is16bit()?1 sampleRate?11025
  60     //     - isStereo?0 is16bit()?1 sampleRate?22050
  61     //     - isStereo?1 is16bit()?1 sampleRate?22050
  62     //     - isStereo?0 is16bit()?1 sampleRate?44100
  63     //     - isStereo?1 is16bit()?1 sampleRate?44100
  64     //
  65     // TODO: test with other sample sizes !
  66     return swfSamples * (outRate / sinfo.getSampleRate());
  67 }
  68
  69 } // namespace sound
  70 } // namespace gnash
  71
  72 #endif