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mixer.cpp

/* 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: https://scummvm.svn.sourceforge.net/svnroot/scummvm/scummvm/tags/release-0-11-1/sound/mixer.cpp $
 * $Id: mixer.cpp 30944 2008-02-23 22:50:18Z sev $
 *
 */

#include "common/file.h"
#include "common/util.h"
#include "common/system.h"

#include "sound/mixer.h"
#include "sound/rate.h"
#include "sound/audiostream.h"


namespace Audio {

#pragma mark -
#pragma mark --- Channel classes ---
#pragma mark -


/**
 * Channels used by the sound mixer.
 */
00045 class Channel {
public:
      const Mixer::SoundType  _type;
      SoundHandle _handle;
private:
      Mixer *_mixer;
      bool _autofreeStream;
      bool _permanent;
      byte _volume;
      int8 _balance;
      int _pauseLevel;
      int _id;
      uint32 _samplesConsumed;
      uint32 _samplesDecoded;
      uint32 _mixerTimeStamp;

protected:
      RateConverter *_converter;
      AudioStream *_input;

public:
      Channel(Mixer *mixer, Mixer::SoundType type, AudioStream *input, bool autofreeStream, bool reverseStereo = false, int id = -1, bool permanent = false);
      virtual ~Channel();

      void mix(int16 *data, uint len);

      bool isPermanent() const {
            return _permanent;
      }
      bool isFinished() const {
            return _input->endOfStream();
      }
      void pause(bool paused) {
            //assert((paused && _pauseLevel >= 0) || (!paused && _pauseLevel));

            if (paused)
                  _pauseLevel++;
            else if (_pauseLevel > 0)
                  _pauseLevel--;
      }
      bool isPaused() {
            return _pauseLevel != 0;
      }
      void setVolume(const byte volume) {
            _volume = volume;
      }
      void setBalance(const int8 balance) {
            _balance = balance;
      }
      int getId() const {
            return _id;
      }
      uint32 getElapsedTime();
};


#pragma mark -
#pragma mark --- Mixer ---
#pragma mark -


Mixer::Mixer() {
      _syst = g_system;

      _handleSeed = 0;

      int i = 0;

      for (i = 0; i < ARRAYSIZE(_volumeForSoundType); i++)
            _volumeForSoundType[i] = kMaxMixerVolume;

      for (i = 0; i != NUM_CHANNELS; i++)
            _channels[i] = 0;

      _mixerReady = false;
}

Mixer::~Mixer() {
      for (int i = 0; i != NUM_CHANNELS; i++)
            delete _channels[i];
}

00127 uint Mixer::getOutputRate() const {
      return (uint)_syst->getOutputSampleRate();
}

void Mixer::insertChannel(SoundHandle *handle, Channel *chan) {

      int index = -1;
      for (int i = 0; i != NUM_CHANNELS; i++) {
            if (_channels[i] == 0) {
                  index = i;
                  break;
            }
      }
      if (index == -1) {
            warning("Mixer::out of mixer slots");
            delete chan;
            return;
      }

      _channels[index] = chan;
       chan->_handle._val = index + (_handleSeed * NUM_CHANNELS);
      _handleSeed++;
      if (handle) {
            *handle = chan->_handle;
      }
}

00154 void Mixer::playRaw(
                  SoundType type,
                  SoundHandle *handle,
                  void *sound,
                  uint32 size, uint rate, byte flags,
                  int id, byte volume, int8 balance,
                  uint32 loopStart, uint32 loopEnd) {

      // Create the input stream
      AudioStream *input = makeLinearInputStream((byte *)sound, size, rate, flags, loopStart, loopEnd);

      // Play it
      playInputStream(type, handle, input, id, volume, balance, true, false, ((flags & Mixer::FLAG_REVERSE_STEREO) != 0));
}

00169 void Mixer::playInputStream(
                  SoundType type,
                  SoundHandle *handle,
                  AudioStream *input,
                  int id, byte volume, int8 balance,
                  bool autofreeStream,
                  bool permanent,
                  bool reverseStereo) {
      Common::StackLock lock(_mutex);

      if (input == 0) {
            warning("input stream is 0");
            return;
      }

      // Prevent duplicate sounds
      if (id != -1) {
            for (int i = 0; i != NUM_CHANNELS; i++)
                  if (_channels[i] != 0 && _channels[i]->getId() == id) {
                        if (autofreeStream)
                              delete input;
                        return;
                  }
      }

      // Create the channel
      Channel *chan = new Channel(this, type, input, autofreeStream, reverseStereo, id, permanent);
      chan->setVolume(volume);
      chan->setBalance(balance);
      insertChannel(handle, chan);
}

00201 void Mixer::mix(int16 *buf, uint len) {
      Common::StackLock lock(_mutex);

      // Since the mixer callback has been called, the mixer must be ready...
      _mixerReady = true;

      //  zero the buf
      memset(buf, 0, 2 * len * sizeof(int16));

      // mix all channels
      for (int i = 0; i != NUM_CHANNELS; i++)
            if (_channels[i]) {
                  if (_channels[i]->isFinished()) {
                        delete _channels[i];
                        _channels[i] = 0;
                  } else if (!_channels[i]->isPaused())
                        _channels[i]->mix(buf, len);
            }
}

00221 void Mixer::mixCallback(void *s, byte *samples, int len) {
      assert(s);
      assert(samples);
      // Len is the number of bytes in the buffer; we divide it by
      // four to get the number of samples (stereo 16 bit).
      ((Mixer *)s)->mix((int16 *)samples, len >> 2);
}

00229 void Mixer::stopAll() {
      Common::StackLock lock(_mutex);
      for (int i = 0; i != NUM_CHANNELS; i++) {
            if (_channels[i] != 0 && !_channels[i]->isPermanent()) {
                  delete _channels[i];
                  _channels[i] = 0;
            }
      }
}

00239 void Mixer::stopID(int id) {
      Common::StackLock lock(_mutex);
      for (int i = 0; i != NUM_CHANNELS; i++) {
            if (_channels[i] != 0 && _channels[i]->getId() == id) {
                  delete _channels[i];
                  _channels[i] = 0;
            }
      }
}

00249 void Mixer::stopHandle(SoundHandle handle) {
      Common::StackLock lock(_mutex);

      // Simply ignore stop requests for handles of sounds that already terminated
      const int index = handle._val % NUM_CHANNELS;
      if (!_channels[index] || _channels[index]->_handle._val != handle._val)
            return;

      delete _channels[index];
      _channels[index] = 0;
}

00261 void Mixer::setChannelVolume(SoundHandle handle, byte volume) {
      Common::StackLock lock(_mutex);

      const int index = handle._val % NUM_CHANNELS;
      if (!_channels[index] || _channels[index]->_handle._val != handle._val)
            return;

      _channels[index]->setVolume(volume);
}

00271 void Mixer::setChannelBalance(SoundHandle handle, int8 balance) {
      Common::StackLock lock(_mutex);

      const int index = handle._val % NUM_CHANNELS;
      if (!_channels[index] || _channels[index]->_handle._val != handle._val)
            return;

      _channels[index]->setBalance(balance);
}

00281 uint32 Mixer::getSoundElapsedTime(SoundHandle handle) {
      Common::StackLock lock(_mutex);

      const int index = handle._val % NUM_CHANNELS;
      if (!_channels[index] || _channels[index]->_handle._val != handle._val)
            return 0;

      return _channels[index]->getElapsedTime();
}

00291 void Mixer::pauseAll(bool paused) {
      Common::StackLock lock(_mutex);
      for (int i = 0; i != NUM_CHANNELS; i++) {
            if (_channels[i] != 0) {
                  _channels[i]->pause(paused);
            }
      }
}

00300 void Mixer::pauseID(int id, bool paused) {
      Common::StackLock lock(_mutex);
      for (int i = 0; i != NUM_CHANNELS; i++) {
            if (_channels[i] != 0 && _channels[i]->getId() == id) {
                  _channels[i]->pause(paused);
                  return;
            }
      }
}

00310 void Mixer::pauseHandle(SoundHandle handle, bool paused) {
      Common::StackLock lock(_mutex);

      // Simply ignore (un)pause requests for sounds that already terminated
      const int index = handle._val % NUM_CHANNELS;
      if (!_channels[index] || _channels[index]->_handle._val != handle._val)
            return;

      _channels[index]->pause(paused);
}

00321 bool Mixer::isSoundIDActive(int id) {
      Common::StackLock lock(_mutex);
      for (int i = 0; i != NUM_CHANNELS; i++)
            if (_channels[i] && _channels[i]->getId() == id)
                  return true;
      return false;
}

00329 int Mixer::getSoundID(SoundHandle handle) {
      Common::StackLock lock(_mutex);
      const int index = handle._val % NUM_CHANNELS;
      if (_channels[index] && _channels[index]->_handle._val == handle._val)
            return _channels[index]->getId();
      return 0;
}

00337 bool Mixer::isSoundHandleActive(SoundHandle handle) {
      Common::StackLock lock(_mutex);
      const int index = handle._val % NUM_CHANNELS;
      return _channels[index] && _channels[index]->_handle._val == handle._val;
}

00343 bool Mixer::hasActiveChannelOfType(SoundType type) {
      Common::StackLock lock(_mutex);
      for (int i = 0; i != NUM_CHANNELS; i++)
            if (_channels[i] && _channels[i]->_type == type)
                  return true;
      return false;
}

00351 void Mixer::setVolumeForSoundType(SoundType type, int volume) {
      assert(0 <= type && type < ARRAYSIZE(_volumeForSoundType));

      // Check range
      if (volume > kMaxMixerVolume)
            volume = kMaxMixerVolume;
      else if (volume < 0)
            volume = 0;

      // TODO: Maybe we should do logarithmic (not linear) volume
      // scaling? See also Player_V2::setMasterVolume

      _volumeForSoundType[type] = volume;
}

00366 int Mixer::getVolumeForSoundType(SoundType type) const {
      assert(0 <= type && type < ARRAYSIZE(_volumeForSoundType));

      return _volumeForSoundType[type];
}


#pragma mark -
#pragma mark --- Channel implementations ---
#pragma mark -


Channel::Channel(Mixer *mixer, Mixer::SoundType type, AudioStream *input,
                        bool autofreeStream, bool reverseStereo, int id, bool permanent)
      : _type(type), _mixer(mixer), _autofreeStream(autofreeStream),
        _volume(Mixer::kMaxChannelVolume), _balance(0), _pauseLevel(0), _id(id), _samplesConsumed(0),
        _samplesDecoded(0), _mixerTimeStamp(0), _converter(0), _input(input), _permanent(permanent) {
      assert(mixer);
      assert(input);

      // Get a rate converter instance
      _converter = makeRateConverter(_input->getRate(), mixer->getOutputRate(), _input->isStereo(), reverseStereo);
}

Channel::~Channel() {
      delete _converter;
      if (_autofreeStream)
            delete _input;
}

/* len indicates the number of sample *pairs*. So a value of
   10 means that the buffer contains twice 10 sample, each
   16 bits, for a total of 40 bytes.
 */
void Channel::mix(int16 *data, uint len) {
      assert(_input);

      if (_input->endOfData()) {
            // TODO: call drain method
      } else {
            assert(_converter);

            // From the channel balance/volume and the global volume, we compute
            // the effective volume for the left and right channel. Note the
            // slightly odd divisor: the 255 reflects the fact that the maximal
            // value for _volume is 255, while the 127 is there because the
            // balance value ranges from -127 to 127.  The mixer (music/sound)
            // volume is in the range 0 - kMaxMixerVolume.
            // Hence, the vol_l/vol_r values will be in that range, too

            int vol = _mixer->getVolumeForSoundType(_type) * _volume;
            st_volume_t vol_l, vol_r;

            if (_balance == 0) {
                  vol_l = vol / Mixer::kMaxChannelVolume;
                  vol_r = vol / Mixer::kMaxChannelVolume;
            } else if (_balance < 0) {
                  vol_l = vol / Mixer::kMaxChannelVolume;
                  vol_r = ((127 + _balance) * vol) / (Mixer::kMaxChannelVolume * 127);
            } else {
                  vol_l = ((127 - _balance) * vol) / (Mixer::kMaxChannelVolume * 127);
                  vol_r = vol / Mixer::kMaxChannelVolume;
            }

            _samplesConsumed = _samplesDecoded;
            _mixerTimeStamp = g_system->getMillis();

            _converter->flow(*_input, data, len, vol_l, vol_r);

            _samplesDecoded += len;
      }
}

uint32 Channel::getElapsedTime() {
      if (_mixerTimeStamp == 0)
            return 0;

      // Convert the number of samples into a time duration. To avoid
      // overflow, this has to be done in a somewhat non-obvious way.

      uint rate = _mixer->getOutputRate();

      uint32 seconds = _samplesConsumed / rate;
      uint32 milliseconds = (1000 * (_samplesConsumed % rate)) / rate;

      uint32 delta = g_system->getMillis() - _mixerTimeStamp;

      // In theory it would seem like a good idea to limit the approximation
      // so that it never exceeds the theoretical upper bound set by
      // _samplesDecoded. Meanwhile, back in the real world, doing so makes
      // the Broken Sword cutscenes noticeably jerkier. I guess the mixer
      // isn't invoked at the regular intervals that I first imagined.

      // FIXME: This won't work very well if the sound is paused.
      return 1000 * seconds + milliseconds + delta;
}


} // End of namespace Audio

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