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mp3.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/mp3.cpp $
 * $Id: mp3.cpp 30944 2008-02-23 22:50:18Z sev $
 *
 */

#include "sound/mp3.h"

#ifdef USE_MAD

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

#include "sound/audiocd.h"
#include "sound/audiostream.h"

#include <mad.h>


namespace Audio {


#pragma mark -
#pragma mark --- MP3 (MAD) stream ---
#pragma mark -


class MP3InputStream : public AudioStream {
protected:
      enum State {
            MP3_STATE_INIT,   // Need to init the decoder
            MP3_STATE_READY,  // ready for processing data
            MP3_STATE_EOS           // end of data reached (may need to loop)
      };

      Common::SeekableReadStream *_inStream;
      bool _disposeAfterUse;
      
      uint _numLoops;
      uint _posInFrame;
      State _state;
      
      const mad_timer_t _startTime;
      const mad_timer_t _endTime;
      mad_timer_t _totalTime;
      
      mad_stream _stream;
      mad_frame _frame;
      mad_synth _synth;

      enum {
            BUFFER_SIZE = 5 * 8192
      };
      
      // This buffer contains a slab of input data
      byte _buf[BUFFER_SIZE + MAD_BUFFER_GUARD];

public:
      MP3InputStream(Common::SeekableReadStream *inStream,
                     bool dispose,
                     mad_timer_t start = mad_timer_zero,
                     mad_timer_t end = mad_timer_zero,
                     uint numLoops = 1);
      ~MP3InputStream();
      
      int readBuffer(int16 *buffer, const int numSamples);

      bool endOfData() const        { return _state == MP3_STATE_EOS; }
      bool isStereo() const         { return MAD_NCHANNELS(&_frame.header) == 2; }
      int getRate() const                 { return _frame.header.samplerate; }

protected:
      void decodeMP3Data();
      void readMP3Data();
};

MP3InputStream::MP3InputStream(Common::SeekableReadStream *inStream, bool dispose, mad_timer_t start, mad_timer_t end, uint numLoops) :
      _inStream(inStream),
      _disposeAfterUse(dispose),
      _numLoops(numLoops),
      _posInFrame(0),
      _state(MP3_STATE_INIT),
      _startTime(start),
      _endTime(end),
      _totalTime(mad_timer_zero) {

      // Make sure that either start < end, or end is zero (indicating "play until end")
      assert(mad_timer_compare(_startTime, _endTime) < 0 || mad_timer_sign(_endTime) == 0);

      // The MAD_BUFFER_GUARD must always contain zeros (the reason
      // for this is that the Layer III Huffman decoder of libMAD
      // may read a few bytes beyond the end of the input buffer).
      memset(_buf + BUFFER_SIZE, 0, MAD_BUFFER_GUARD);

      // Decode the first chunk of data. This is necessary so that _frame
      // is setup and isStereo() and getRate() return correct results.
      decodeMP3Data();
}

MP3InputStream::~MP3InputStream() {
      if (_state != MP3_STATE_INIT) {
            // Deinit MAD
            mad_synth_finish(&_synth);
            mad_frame_finish(&_frame);
            mad_stream_finish(&_stream);
      }

      if (_disposeAfterUse)
            delete _inStream;
}

void MP3InputStream::decodeMP3Data() {

      do {
            if (_state == MP3_STATE_INIT) {
                  // Init MAD
                  mad_stream_init(&_stream);
                  mad_frame_init(&_frame);
                  mad_synth_init(&_synth);
      
                  // Reset the stream data
                  _inStream->seek(0, SEEK_SET);
                  _totalTime = mad_timer_zero;
                  _posInFrame = 0;
            
                  // Update state
                  _state = MP3_STATE_READY;
      
                  // Read the first few sample bytes
                  readMP3Data();
            }
      
            if (_state == MP3_STATE_EOS)
                  return;

            // If necessary, load more data into the stream decoder
            if (_stream.error == MAD_ERROR_BUFLEN)
                  readMP3Data();

            while (_state == MP3_STATE_READY) {
                  _stream.error = MAD_ERROR_NONE;

                  // Decode the next header. Note: mad_frame_decode would do this for us, too.
                  // However, for seeking we don't want to decode the full frame (else it would
                  // be far too slow). Hence we perform this explicitly in a separate step.
                  if (mad_header_decode(&_frame.header, &_stream) == -1) {
                        if (_stream.error == MAD_ERROR_BUFLEN) {
                              break; // Read more data
                        } else if (MAD_RECOVERABLE(_stream.error)) {
                              debug(6, "MP3InputStream: Recoverable error in mad_header_decode (%s)", mad_stream_errorstr(&_stream));
                              continue;
                        } else {
                              warning("MP3InputStream: Unrecoverable error in mad_header_decode (%s)", mad_stream_errorstr(&_stream));
                              break;
                        }
                  }
            
                  // Sum up the total playback time so far
                  mad_timer_add(&_totalTime, _frame.header.duration);
                  
                  // If we have not yet reached the start point, skip to the next frame
                  if (mad_timer_compare(_totalTime, _startTime) < 0)
                        continue;

                  // If an end time is specified and we are past it, stop
                  if (mad_timer_sign(_endTime) > 0 && mad_timer_compare(_totalTime, _endTime) >= 0) {
                        _state = MP3_STATE_EOS;
                        break;
                  }
                  
                  // Decode the next frame
                  if (mad_frame_decode(&_frame, &_stream) == -1) {
                        if (_stream.error == MAD_ERROR_BUFLEN) {
                              break; // Read more data
                        } else if (MAD_RECOVERABLE(_stream.error)) {
                              // Note: we will occasionally see MAD_ERROR_BADDATAPTR errors here.
                              // These are normal and expected (caused by our frame skipping (i.e. "seeking")
                              // code above).
                              debug(6, "MP3InputStream: Recoverable error in mad_frame_decode (%s)", mad_stream_errorstr(&_stream));
                              continue;
                        } else {
                              warning("MP3InputStream: Unrecoverable error in mad_frame_decode (%s)", mad_stream_errorstr(&_stream));
                              break;
                        }
                  }
                  
                  // Synthesize PCM data
                  mad_synth_frame(&_synth, &_frame);
                  _posInFrame = 0;
                  break;
            }
      
            if (_state == MP3_STATE_EOS && _numLoops != 1) {
                  // If looping is on and there are loops left, rewind to the start
                  if (_numLoops != 0)
                        _numLoops--;

                  // Deinit MAD
                  mad_synth_finish(&_synth);
                  mad_frame_finish(&_frame);
                  mad_stream_finish(&_stream);
                  
                  // Reset the decoder state to indicate we should start over
                  _state = MP3_STATE_INIT;
            }

      } while (_state != MP3_STATE_EOS && _stream.error == MAD_ERROR_BUFLEN);
      
      if (_stream.error != MAD_ERROR_NONE)
            _state = MP3_STATE_EOS;
}

void MP3InputStream::readMP3Data() {
      uint32 remaining = 0;

      // Give up immediately if we already used up all data in the stream
      if (_inStream->eos()) {
            _state = MP3_STATE_EOS;
            return;
      }

      if (_stream.next_frame) {
            // If there is still data in the MAD stream, we need to preserve it.
            // Note that we use memmove, as we are reusing the same buffer,
            // and hence the data regions we copy from and to may overlap.
            remaining = _stream.bufend - _stream.next_frame;
            assert(remaining < BUFFER_SIZE);    // Paranoia check
            memmove(_buf, _stream.next_frame, remaining);
      }

      // Try to read the next block
      uint32 size = _inStream->read(_buf + remaining, BUFFER_SIZE - remaining);
      if (size <= 0) {
            _state = MP3_STATE_EOS;
            return;
      }
      
      // Feed the data we just read into the stream decoder
      _stream.error = MAD_ERROR_NONE;
      mad_stream_buffer(&_stream, _buf, size + remaining);
}


static inline int scale_sample(mad_fixed_t sample) {
      // round
      sample += (1L << (MAD_F_FRACBITS - 16));

      // clip
      if (sample > MAD_F_ONE - 1)
            sample = MAD_F_ONE - 1;
      else if (sample < -MAD_F_ONE)
            sample = -MAD_F_ONE;

      // quantize and scale to not saturate when mixing a lot of channels
      return sample >> (MAD_F_FRACBITS + 1 - 16);
}

int MP3InputStream::readBuffer(int16 *buffer, const int numSamples) {
      int samples = 0;
      // Keep going as long as we have input available
      while (samples < numSamples && _state != MP3_STATE_EOS) {
            const int len = MIN(numSamples, samples + (int)(_synth.pcm.length - _posInFrame) * MAD_NCHANNELS(&_frame.header));
            while (samples < len) {
                  *buffer++ = (int16)scale_sample(_synth.pcm.samples[0][_posInFrame]);
                  samples++;
                  if (MAD_NCHANNELS(&_frame.header) == 2) {
                        *buffer++ = (int16)scale_sample(_synth.pcm.samples[1][_posInFrame]);
                        samples++;
                  }
                  _posInFrame++;
            }
            if (_posInFrame >= _synth.pcm.length) {
                  // We used up all PCM data in the current frame -- read & decode more
                  decodeMP3Data();
            }
      }
      return samples;
}


#pragma mark -
#pragma mark --- MP3 factory functions ---
#pragma mark -


AudioStream *makeMP3Stream(
      Common::SeekableReadStream *stream,
      bool disposeAfterUse,
      uint32 startTime,
      uint32 duration,
      uint numLoops) {

      mad_timer_t start;
      mad_timer_t end;

      // Both startTime and duration are given in milliseconds.
      // Calculate the appropriate mad_timer_t values from them.
      mad_timer_set(&start, startTime / 1000, startTime % 1000, 1000);
      if (duration == 0) {
            end = mad_timer_zero;
      } else {
            int endTime = startTime + duration;
            mad_timer_set(&end, endTime / 1000, endTime % 1000, 1000);
      }

      return new MP3InputStream(stream, disposeAfterUse, start, end, numLoops);
}

} // End of namespace Audio

#endif // #ifdef USE_MAD

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