speexproperties.cpp

来自「Amarok是一款在LINUX或其他类UNIX操作系统中运行的音频播放器软件。 」· C++ 代码 · 共 172 行

/***************************************************************************
    copyright            : (C) 2006 by Lukáš Lalinský
    email                : [e-mail]
    
    copyright            : (C) 2002 by Scott Wheeler
    email                : [e-mail] 
                           (original Vorbis implementation)
 ***************************************************************************/

/***************************************************************************
 *   This library is free software; you can redistribute it and/or modify  *
 *   it  under the terms of the GNU Lesser General Public License version  *
 *   2.1 as published by the Free Software Foundation.                     *
 *                                                                         *
 *   This library 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     *
 *   Lesser General Public License for more details.                       *
 *                                                                         *
 *   You should have received a copy of the GNU Lesser General Public      *
 *   License along with this library; if not, write to the Free Software   *
 *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,            *
 *   MA  02110-1301  USA                                                   *
 ***************************************************************************/

#include <tstring.h>
#if 0
#include <tdebug.h>
#endif

#include <oggpageheader.h>

#include "speexproperties.h"
#include "speexfile.h"

using namespace TagLib;

class Speex::Properties::PropertiesPrivate
{
public:
  PropertiesPrivate(File *f, ReadStyle s) :
    file(f),
    style(s),
    length(0),
    bitrate(0),
    sampleRate(0),
    channels(0),
    speexVersion(0),
    vbr(false),
    mode(0) {}

  File *file;
  ReadStyle style;
  int length;
  int bitrate;
  int sampleRate;
  int channels;
  int speexVersion;
  bool vbr;
  int mode;
};

////////////////////////////////////////////////////////////////////////////////
// public members
////////////////////////////////////////////////////////////////////////////////

Speex::Properties::Properties(File *file, ReadStyle style) : AudioProperties(style)
{
  d = new PropertiesPrivate(file, style);
  read();
}

Speex::Properties::~Properties()
{
  delete d;
}

int Speex::Properties::length() const
{
  return d->length;
}

int Speex::Properties::bitrate() const
{
  return int(float(d->bitrate) / float(1000) + 0.5);
}

int Speex::Properties::sampleRate() const
{
  return d->sampleRate;
}

int Speex::Properties::channels() const
{
  return d->channels;
}

int Speex::Properties::speexVersion() const
{
  return d->speexVersion;
}

////////////////////////////////////////////////////////////////////////////////
// private members
////////////////////////////////////////////////////////////////////////////////

void Speex::Properties::read()
{
  // Get the identification header from the Ogg implementation.

  ByteVector data = d->file->packet(0);

  int pos = 28;

  // speex_version_id;       /**< Version for Speex (for checking compatibility) */ 
  d->speexVersion = data.mid(pos, 4).toUInt(false);
  pos += 4;
  
  // header_size;            /**< Total size of the header ( sizeof(SpeexHeader) ) */ 
  pos += 4;
  
  // rate;                   /**< Sampling rate used */ 
  d->sampleRate = data.mid(pos, 4).toUInt(false);
  pos += 4;

  // mode;                   /**< Mode used (0 for narrowband, 1 for wideband) */ 
  d->mode = data.mid(pos, 4).toUInt(false);
  pos += 4;

  // mode_bitstream_version; /**< Version ID of the bit-stream */ 
  pos += 4;

  // nb_channels;            /**< Number of channels encoded */ 
  d->channels = data.mid(pos, 4).toUInt(false);
  pos += 4;

  // bitrate;                /**< Bit-rate used */ 
  d->bitrate = data.mid(pos, 4).toUInt(false);
  pos += 4;
  
  // frame_size;             /**< Size of frames */
  //unsigned int frameSize = data.mid(pos, 4).toUInt(false);
  pos += 4;
  
  // vbr;                    /**< 1 for a VBR encoding, 0 otherwise */  
  d->vbr = data.mid(pos, 4).toUInt(false) == 1;
  pos += 4;

  // frames_per_packet;      /**< Number of frames stored per Ogg packet */ 
  //unsigned int framesPerPacket = data.mid(pos, 4).toUInt(false);

  const Ogg::PageHeader *first = d->file->firstPageHeader();
  const Ogg::PageHeader *last = d->file->lastPageHeader();

  if(first && last) {
    long long start = first->absoluteGranularPosition();
    long long end = last->absoluteGranularPosition();

    if(start >= 0 && end >= 0 && d->sampleRate > 0)
      d->length = (end - start) / (long long) d->sampleRate;
#if 0    
    else
      debug("Speex::Properties::read() -- Either the PCM values for the start or "
            "end of this file was incorrect or the sample rate is zero.");
#endif
  }
#if 0    
  else
    debug("Speex::Properties::read() -- Could not find valid first and last Ogg pages.");
#endif
}