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mixer.h

/* ScummVM - Scumm Interpreter
 * Copyright (C) 2001  Ludvig Strigeus
 * Copyright (C) 2001-2004 The ScummVM project
 *
 * 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * $Header: /cvsroot/scummvm/scummvm/sound/mixer.h,v 1.87 2004/11/28 23:24:32 fingolfin Exp $
 *
 */

#ifndef SOUND_MIXER_H
#define SOUND_MIXER_H

#include "stdafx.h"
#include "common/scummsys.h"
#include "common/system.h"


class AudioStream;
class Channel;
class File;

class PlayingSoundHandle {
      friend class Channel;
      friend class SoundMixer;
      int val;
      int getIndex() const { return val - 1; }
      void setIndex(int i) { val = i + 1; }
      void resetIndex() { val = 0; }
public:
      PlayingSoundHandle() { resetIndex(); }
      bool isActive() const { return val > 0; }
};

class SoundMixer {
public:
      enum {
            /** unsigned samples (default: signed) */
            FLAG_UNSIGNED = 1 << 0,

            /** sound is 16 bits wide (default: 8bit) */
            FLAG_16BITS = 1 << 1,

            /** sample is little endian (default: big endian) */
            FLAG_LITTLE_ENDIAN = 1 << 2,

            /** sound is in stereo (default: mono) */
            FLAG_STEREO = 1 << 3,

            /** reverse the left and right stereo channel */
            FLAG_REVERSE_STEREO = 1 << 4,

            /** sound buffer is freed automagically at the end of playing */
            FLAG_AUTOFREE = 1 << 5,

            /** loop the audio */
            FLAG_LOOP = 1 << 6
      };

private:
      enum {
            NUM_CHANNELS = 16
      };

      OSystem *_syst;
      OSystem::MutexRef _mutex;

      Channel *_premixChannel;

      uint _outputRate;

      int _globalVolume;
      int _musicVolume;

      bool _paused;
      
      Channel *_channels[NUM_CHANNELS];

      bool _mixerReady;

public:
      SoundMixer();
      ~SoundMixer();



      /**
       * Is the mixer ready and setup? This may not be the case on systems which
       * don't support digital sound output. In that case, the mixer proc may
       * never be called. That in turn can cause breakage in games which use the
       * premix callback for syncing. In particular, the Adlib MIDI emulation...
       *
       * @return whether the mixer is ready and setup
       */
      bool isReady() const { return _mixerReady; };



      /**
       * Set the premix stream. This is mainly used for the adlib music, but
       * is not limited to it. The premix stream is invoked by the mixer whenever
       * it needs to generate any data, before any other mixing takes place.
       */
      void setupPremix(AudioStream *stream);



      /**
       * Start playing the given raw sound data.
       * Internally, this simply creates an audio input stream wrapping the data
       * (using the makeLinearInputStream factory function), which is then
       * passed on to playInputStream.
       */
      void playRaw(PlayingSoundHandle *handle, void *sound, uint32 size, uint rate, byte flags,
                        int id = -1, byte volume = 255, int8 balance = 0,
                        uint32 loopStart = 0, uint32 loopEnd = 0);

      /**
       * Start playing the given audio input stream.
       */
      void playInputStream(PlayingSoundHandle *handle, AudioStream *input, bool isMusic,
                        int id = -1, byte volume = 255, int8 balance = 0,
                        bool autofreeStream = true, bool permanent = false);



      /**
       * Stop all currently playing sounds.
       */
      void stopAll(bool force = false);

      /**
       * Stop playing the sound with given ID.
       *
       * @param id the ID of the sound to affect
       */
      void stopID(int id);

      /**
       * Stop playing the sound corresponding to the given handle.
       *
       * @param handle the sound to affect
       */
      void stopHandle(PlayingSoundHandle handle);



      /**
       * Pause/unpause the mixer (this temporarily stops all audio processing,
       * including all regular channels and the premix channel).
       *
       * @param paused true to pause the mixer, false to unpause it
       */
      void pauseAll(bool paused);

      /**
       * Pause/unpause the sound with the given ID.
       *
       * @param id the ID of the sound to affect
       * @param paused true to pause the sound, false to unpause it
       */
      void pauseID(int id, bool paused);

      /**
       * Pause/unpause the sound corresponding to the given handle.
       *
       * @param handle the sound to affect
       * @param paused true to pause the sound, false to unpause it
       */
      void pauseHandle(PlayingSoundHandle handle, bool paused);



      /**
       * Check if a sound with the given ID is active.
       *
       * @param id the ID of the sound to query
       * @return true if the sound is active
       */
      bool isSoundIDActive(int id);

      /**
       * Check if the mixer is paused (using pauseAll).
       *
       * @return true if the mixer is paused
       */
      bool isPaused();



      /**
       * Set the channel volume for the given handle.
       *
       * @param handle the sound to affect
       * @param volume the new channel volume (0 - 255)
       */
      void setChannelVolume(PlayingSoundHandle handle, byte volume);

      /**
       * Set the channel balance for the given handle.
       *
       * @param handle the sound to affect
       * @param balance the new channel balance:
       *        (-127 ... 0 ... 127) corresponds to (left ... center ... right)
       */
      void setChannelBalance(PlayingSoundHandle handle, int8 balance);

      /**
       * Get approximation of for how long the channel has been playing.
       */
      uint32 getSoundElapsedTime(PlayingSoundHandle handle);

      /**
       * Check whether any SFX channel is active.
       *
       * @return true if any SFX (= non-music) channels are active.
       */
      bool hasActiveSFXChannel();

      /**
       * Set the global volume.
       *
       * @param volume the new global volume, 0-256
       */
      void setVolume(int volume);

      /**
       * Query the global volume.
       *
       * @return the global music volume, 0-256
       */
      int getVolume() const { return _globalVolume; }

      /**
       * Set the music volume.
       *
       * @param volume the new music volume, 0-256
       */
      void setMusicVolume(int volume);

      /**
       * Query the music volume.
       *
       * @return the current music volume, 0-256
       */
      int getMusicVolume() const { return _musicVolume; }

      /**
       * Query the system's audio output sample rate. This returns
       * the same value as OSystem::getOutputSampleRate().
       *
       * @return the output sample rate in Hz
       */
      uint getOutputRate() const { return _outputRate; }

private:
      void insertChannel(PlayingSoundHandle *handle, Channel *chan);

      /**
       * Internal main method -- all the actual mixing work is done from here.
       */
      void mix(int16 * buf, uint len);

      /**
       * The mixer callback function, passed on to OSystem::setSoundCallback().
       * This simply calls the mix() method.
       */
      static void mixCallback(void *s, byte *samples, int len);
};

#endif

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