Logo Search packages:      
Sourcecode: scummvm version File versions  Download package

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

/*
 * The code in this file is based on information found at
 * http://www.borg.com/~jglatt/tech/aiff.htm
 *
 * We currently only implement uncompressed AIFF. If we ever need AIFF-C, SoX
 * (http://sox.sourceforge.net) may be a good place to start from.
 */

#include "common/endian.h"
#include "common/util.h"
#include "common/stream.h"

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

namespace Audio {

uint32 readExtended(Common::SeekableReadStream &stream) {
      // The sample rate is stored as an "80 bit IEEE Standard 754 floating
      // point number (Standard Apple Numeric Environment [SANE] data type
      // Extended).

      byte buf[10];
      uint32 mantissa;
      uint32 last = 0;
      byte exp;

      stream.read(buf, 10);
      mantissa = READ_BE_UINT32(buf + 2);
      exp = 30 - buf[1];

      while (exp--) {
            last = mantissa;
            mantissa >>= 1;
      }

      if (last & 0x00000001)
            mantissa++;

      return mantissa;
}

bool loadAIFFFromStream(Common::SeekableReadStream &stream, int &size, int &rate, byte &flags) {
      byte buf[4];

      stream.read(buf, 4);
      if (memcmp(buf, "FORM", 4) != 0) {
            warning("loadAIFFFromStream: No 'FORM' header");
            return false;
      }

      stream.readUint32BE();

      // This could be AIFC, but we don't handle that case.

      stream.read(buf, 4);
      if (memcmp(buf, "AIFF", 4) != 0) {
            warning("loadAIFFFromStream: No 'AIFF' header");
            return false;
      }

      // From here on, we only care about the COMM and SSND chunks, which are
      // the only required chunks.

      bool foundCOMM = false;
      bool foundSSND = false;

      uint16 numChannels = 0, bitsPerSample = 0;
      uint32 numSampleFrames = 0, offset = 0, blockSize = 0, soundOffset = 0;

      while ((!foundCOMM || !foundSSND) && !stream.ioFailed()) {
            uint32 length, pos;

            stream.read(buf, 4);
            length = stream.readUint32BE();
            pos = stream.pos();

            if (memcmp(buf, "COMM", 4) == 0) {
                  foundCOMM = true;
                  numChannels = stream.readUint16BE();
                  numSampleFrames = stream.readUint32BE();
                  bitsPerSample = stream.readUint16BE();
                  rate = readExtended(stream);
                  size = numSampleFrames * numChannels * (bitsPerSample / 8);
            } else if (memcmp(buf, "SSND", 4) == 0) {
                  foundSSND = true;
                  offset = stream.readUint32BE();
                  blockSize = stream.readUint32BE();
                  soundOffset = stream.pos();
            }

            stream.seek(pos + length);
      }

      if (!foundCOMM) {
            warning("loadAIFFFromStream: Cound not find 'COMM' chunk");
            return false;
      }

      if (!foundSSND) {
            warning("loadAIFFFromStream: Cound not find 'SSND' chunk");
            return false;
      }

      // We only implement a subset of the AIFF standard.

      if (numChannels < 1 || numChannels > 2) {
            warning("loadAIFFFromStream: Only 1 or 2 channels are supported, not %d", numChannels);
            return false;
      }

      if (bitsPerSample != 8 && bitsPerSample != 16) {
            warning("loadAIFFFromStream: Only 8 or 16 bits per sample are supported, not %d", bitsPerSample);
            return false;
      }

      if (offset != 0 || blockSize != 0) {
            warning("loadAIFFFromStream: Block-aligned data is not supported");
            return false;
      }

      // Samples are always signed, and big endian.

      flags = 0;
      if (bitsPerSample == 16)
            flags |= Audio::Mixer::FLAG_16BITS;
      if (numChannels == 2)
            flags |= Audio::Mixer::FLAG_STEREO;

      stream.seek(soundOffset);

      // Stream now points at the sample data

      return true;
}

AudioStream *makeAIFFStream(Common::SeekableReadStream &stream) {
      int size, rate;
      byte *data, flags;

      if (!loadAIFFFromStream(stream, size, rate, flags))
            return 0;

      data = (byte *)malloc(size);
      assert(data);
      stream.read(data, size);

      // Since we allocated our own buffer for the data, we must set the autofree flag.
      flags |= Audio::Mixer::FLAG_AUTOFREE;

      return makeLinearInputStream(data, size, rate, flags, 0, 0);
}

} // End of namespace Audio

Generated by  Doxygen 1.6.0   Back to index