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audiostream.h

/* 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_AUDIOSTREAM_H
#define SOUND_AUDIOSTREAM_H

#include "common/scummsys.h"
#include "common/str.h"
#include "common/types.h"

#include "audio/timestamp.h"

namespace Audio {

/**
 * Generic audio input stream. Subclasses of this are used to feed arbitrary
 * sampled audio data into ScummVM's audio mixer.
 */
00041 class AudioStream {
public:
      virtual ~AudioStream() {}

      /**
       * Fill the given buffer with up to numSamples samples. Returns the actual
       * number of samples read, or -1 if a critical error occurred (note: you
       * *must* check if this value is less than what you requested, this can
       * happen when the stream is fully used up).
       *
       * Data has to be in native endianess, 16 bit per sample, signed. For stereo
       * stream, buffer will be filled with interleaved left and right channel
       * samples, starting with a left sample. Furthermore, the samples in the
       * left and right are summed up. So if you request 4 samples from a stereo
       * stream, you will get a total of two left channel and two right channel
       * samples.
       */
      virtual int readBuffer(int16 *buffer, const int numSamples) = 0;

      /** Is this a stereo stream? */
      virtual bool isStereo() const = 0;

      /** Sample rate of the stream. */
      virtual int getRate() const = 0;

      /**
       * End of data reached? If this returns true, it means that at this
       * time there is no data available in the stream. However there may be
       * more data in the future.
       * This is used by e.g. a rate converter to decide whether to keep on
       * converting data or stop.
       */
      virtual bool endOfData() const = 0;

      /**
       * End of stream reached? If this returns true, it means that all data
       * in this stream is used up and no additional data will appear in it
       * in the future.
       * This is used by the mixer to decide whether a given stream shall be
       * removed from the list of active streams (and thus be destroyed).
       * By default this maps to endOfData()
       */
00083       virtual bool endOfStream() const { return endOfData(); }
};

/**
 * A rewindable audio stream. This allows for reseting the AudioStream
 * to its initial state. Note that rewinding itself is not required to
 * be working when the stream is being played by Mixer!
 */
00091 class RewindableAudioStream : public AudioStream {
public:
      /**
       * Rewinds the stream to its start.
       *
       * @return true on success, false otherwise.
       */
      virtual bool rewind() = 0;
};

/**
 * A looping audio stream. This object does nothing besides using
 * a RewindableAudioStream to play a stream in a loop.
 */
00105 class LoopingAudioStream : public AudioStream {
public:
      /**
       * Creates a looping audio stream object.
       *
       * Note that on creation of the LoopingAudioStream object
       * the underlying stream will be rewound.
       *
       * @see makeLoopingAudioStream
       *
       * @param stream Stream to loop
       * @param loops How often to loop (0 = infinite)
       * @param disposeAfterUse Destroy the stream after the LoopingAudioStream has finished playback.
       */
      LoopingAudioStream(RewindableAudioStream *stream, uint loops, DisposeAfterUse::Flag disposeAfterUse = DisposeAfterUse::YES);
      ~LoopingAudioStream();

      int readBuffer(int16 *buffer, const int numSamples);
      bool endOfData() const;

00125       bool isStereo() const { return _parent->isStereo(); }
00126       int getRate() const { return _parent->getRate(); }

      /**
       * Returns number of loops the stream has played.
       *
       * @param numLoops number of loops to play, 0 - infinite
       */
00133       uint getCompleteIterations() const { return _completeIterations; }
private:
      RewindableAudioStream *_parent;
      DisposeAfterUse::Flag _disposeAfterUse;

      uint _loops;
      uint _completeIterations;
};

/**
 * Wrapper functionality to efficiently create a stream, which might be looped.
 *
 * Note that this function does not return a LoopingAudioStream, because it does
 * not create one when the loop count is "1". This allows to keep the runtime
 * overhead down, when the code does not require any functionality only offered
 * by LoopingAudioStream.
 *
 * @param stream  Stream to loop (will be automatically destroyed, when the looping is done)
 * @param loops   How often to loop (0 = infinite)
 * @return A new AudioStream, which offers the desired functionality.
 */
AudioStream *makeLoopingAudioStream(RewindableAudioStream *stream, uint loops);

/**
 * A seekable audio stream. Subclasses of this class implement an
 * interface for seeking. The seeking itself is not required to be
 * working while the stream is being played by Mixer!
 */
00161 class SeekableAudioStream : public RewindableAudioStream {
public:
      /**
       * Tries to load a file by trying all available formats.
       * In case of an error, the file handle will be closed, but deleting
       * it is still the responsibility of the caller.
       *
       * @param basename a filename without an extension
       * @return  an SeekableAudioStream ready to use in case of success;
       *          NULL in case of an error (e.g. invalid/nonexisting file)
       */
      static SeekableAudioStream *openStreamFile(const Common::String &basename);

      /**
       * Seeks to a given offset in the stream.
       *
       * @param where offset in milliseconds
       * @return true on success, false on failure.
       */
00180       bool seek(uint32 where) {
            return seek(Timestamp(where, getRate()));
      }

      /**
       * Seeks to a given offset in the stream.
       *
       * @param where offset as timestamp
       * @return true on success, false on failure.
       */
      virtual bool seek(const Timestamp &where) = 0;

      /**
       * Returns the length of the stream.
       *
       * @return length as Timestamp.
       */
      virtual Timestamp getLength() const = 0;

00199       virtual bool rewind() { return seek(0); }
};

/**
 * Wrapper functionality to efficiently create a stream, which might be looped
 * in a certain interval.
 *
 * This automatically starts the stream at time "start"!
 *
 * Note that this function does not return a LoopingAudioStream, because it does
 * not create one when the loop count is "1". This allows to keep the runtime
 * overhead down, when the code does not require any functionality only offered
 * by LoopingAudioStream.
 *
 * @param stream Stream to loop (will be automatically destroyed, when the looping is done)
 * @param start  Starttime of the stream interval to be looped
 * @param end    End of the stream interval to be looped (a zero time, means till end)
 * @param loops  How often to loop (0 = infinite)
 * @return A new AudioStream, which offers the desired functionality.
 */
AudioStream *makeLoopingAudioStream(SeekableAudioStream *stream, Timestamp start, Timestamp end, uint loops);

/**
 * A looping audio stream, which features looping of a nested part of the
 * stream.
 *
 * NOTE:
 * Currently this implementation stops after the nested loop finished
 * playback.
 *
 * IMPORTANT:
 * This might be merged with SubSeekableAudioStream for playback purposes.
 * (After extending it to accept a start time).
 */
00233 class SubLoopingAudioStream : public AudioStream {
public:
      /**
       * Constructor for a SubLoopingAudioStream.
       *
       * Note that on creation of the SubLoopingAudioStream object
       * the underlying stream will be rewound.
       *
       * @param stream          Stream to loop
       * @param loops           How often the stream should be looped (0 means infinite)
       * @param loopStart       Start of the loop (this must be smaller than loopEnd)
       * @param loopEnd         End of the loop (thus must be greater than loopStart)
       * @param disposeAfterUse Whether the stream should be disposed, when the
       *                        SubLoopingAudioStream is destroyed.
       */
      SubLoopingAudioStream(SeekableAudioStream *stream, uint loops,
                            const Timestamp loopStart,
                            const Timestamp loopEnd,
                            DisposeAfterUse::Flag disposeAfterUse = DisposeAfterUse::YES);
      ~SubLoopingAudioStream();

      int readBuffer(int16 *buffer, const int numSamples);
00255       bool endOfData() const { return _done; }

00257       bool isStereo() const { return _parent->isStereo(); }
00258       int getRate() const { return _parent->getRate(); }
private:
      SeekableAudioStream *_parent;
      DisposeAfterUse::Flag _disposeAfterUse;

      uint _loops;
      Timestamp _pos;
      Timestamp _loopStart, _loopEnd;

      bool _done;
};


/**
 * A SubSeekableAudioStream provides access to a SeekableAudioStream
 * just in the range [start, end).
 * The same caveats apply to SubSeekableAudioStream as do to SeekableAudioStream.
 *
 * Manipulating the parent stream directly /will/ mess up a substream.
 */
00278 class SubSeekableAudioStream : public SeekableAudioStream {
public:
      /**
       * Creates a new SubSeekableAudioStream.
       *
       * @param parent          parent stream object.
       * @param start           Start time.
       * @param end             End time.
       * @param disposeAfterUse Whether the parent stream object should be destroyed on destruction of the SubSeekableAudioStream.
       */
      SubSeekableAudioStream(SeekableAudioStream *parent, const Timestamp start, const Timestamp end, DisposeAfterUse::Flag disposeAfterUse = DisposeAfterUse::YES);
      ~SubSeekableAudioStream();

      int readBuffer(int16 *buffer, const int numSamples);

00293       bool isStereo() const { return _parent->isStereo(); }

00295       int getRate() const { return _parent->getRate(); }

00297       bool endOfData() const { return (_pos >= _length) || _parent->endOfStream(); }

      bool seek(const Timestamp &where);

00301       Timestamp getLength() const { return _length; }
private:
      SeekableAudioStream *_parent;
      DisposeAfterUse::Flag _disposeAfterUse;

      const Timestamp _start;
      const Timestamp _length;
      Timestamp _pos;
};

00311 class QueuingAudioStream : public Audio::AudioStream {
public:

      /**
       * Queue an audio stream for playback. This stream plays all queued
       * streams, in the order they were queued. If disposeAfterUse is set to
       * DisposeAfterUse::YES, then the queued stream is deleted after all data
       * contained in it has been played.
       */
      virtual void queueAudioStream(Audio::AudioStream *audStream,
                                    DisposeAfterUse::Flag disposeAfterUse = DisposeAfterUse::YES) = 0;

      /**
       * Queue a block of raw audio data for playback. This stream plays all
       * queued block, in the order they were queued. If disposeAfterUse is set
       * to DisposeAfterUse::YES, then the queued block is released using free()
       * after all data contained in it has been played.
       *
       * @note Make sure to allocate the data block with malloc(), not with new[].
       *
       * @param data             pointer to the audio data block
       * @param size             length of the audio data block
       * @param disposeAfterUse  if equal to DisposeAfterUse::YES, the block is released using free() after use.
       * @param flags            a bit-ORed combination of RawFlags describing the audio data format
       */
      void queueBuffer(byte *data, uint32 size, DisposeAfterUse::Flag disposeAfterUse, byte flags);

      /**
       * Mark this stream as finished. That is, signal that no further data
       * will be queued to it. Only after this has been done can this
       * stream ever 'end'.
       */
      virtual void finish() = 0;

      /**
       * Return the number of streams still queued for playback (including
       * the currently playing stream).
       */
      virtual uint32 numQueuedStreams() const = 0;
};

/**
 * Factory function for an QueuingAudioStream.
 */
QueuingAudioStream *makeQueuingAudioStream(int rate, bool stereo);

/**
 * Converts a point in time to a precise sample offset
 * with the given parameters.
 *
 * @param where    Point in time.
 * @param rate     Rate of the stream.
 * @param isStereo Is the stream a stereo stream?
 */
Timestamp convertTimeToStreamPos(const Timestamp &where, int rate, bool isStereo);

} // End of namespace Audio

#endif

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