tag_render.cpp

FreeAMP(MP3播放)程序源代码-用来研究MP3解码

// $Id: tag_render.cpp,v 1.2 2001/01/16 21:08:01 robert Exp $

// id3lib: a C++ library for creating and manipulating id3v1/v2 tags
// Copyright 1999, 2000  Scott Thomas Haug

// This library is free software; you can redistribute it and/or modify it
// under the terms of the GNU Library General Public License as published by
// the Free Software Foundation; either version 2 of the License, or (at your
// option) any later version.
//
// 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 Library General Public
// License for more details.
//
// You should have received a copy of the GNU Library General Public License
// along with this library; if not, write to the Free Software Foundation,
// Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

// The id3lib authors encourage improvements and optimisations to be sent to
// the id3lib coordinator.  Please see the README file for details on where to
// send such submissions.  See the AUTHORS file for a list of people who have
// contributed to id3lib.  See the ChangeLog file for a list of changes to
// id3lib.  These files are distributed with id3lib at
// http://download.sourceforge.net/id3lib/

#include "config.h"
#include "id3config.h"
#include <stdlib.h>
#include <string.h>
#include <memory.h>
#include "tag_impl.h"
#include "helpers.h"
#include "utils.h"
#include "writers.h"
#include "io_decorators.h"
#include "io_helpers.h"
#include "io_strings.h"

#if defined HAVE_SYS_PARAM_H
#include <sys/param.h>
#endif

using namespace dami;

void id3::v1::render(ID3_Writer& writer, const ID3_TagImpl& tag)
{
  writer.writeChars("TAG", 3);
  
  io::writeTrailingSpaces(writer, id3::v2::getTitle(tag),  ID3_V1_LEN_TITLE);
  io::writeTrailingSpaces(writer, id3::v2::getArtist(tag), ID3_V1_LEN_ARTIST);
  io::writeTrailingSpaces(writer, id3::v2::getAlbum(tag),  ID3_V1_LEN_ALBUM);
  io::writeTrailingSpaces(writer, id3::v2::getYear(tag),   ID3_V1_LEN_YEAR);
  
  size_t track = id3::v2::getTrackNum(tag);
  String comment = id3::v2::getV1Comment(tag);
  if (track > 0)
  {
    io::writeTrailingSpaces(writer, comment, ID3_V1_LEN_COMMENT - 2);
    writer.writeChar('\0');
    writer.writeChar((char) track);
  }
  else
  {
    io::writeTrailingSpaces(writer, comment, ID3_V1_LEN_COMMENT);
  }
  writer.writeChar((char) id3::v2::getGenreNum(tag));
}

namespace
{
  void renderFrames(ID3_Writer& writer, const ID3_TagImpl& tag)
  {
    for (ID3_TagImpl::const_iterator iter = tag.begin(); iter != tag.end(); ++iter)
    {
      const ID3_Frame* frame = *iter;
      if (frame) frame->Render(writer);
    }
  }
}

void id3::v2::render(ID3_Writer& writer, const ID3_TagImpl& tag)
{
  // There has to be at least one frame for there to be a tag...
  if (tag.NumFrames() == 0)
  {
    ID3D_WARNING( "id3::v2::render(): no frames to render" );
    return;
  }
  
  ID3D_NOTICE( "id3::v2::render(): rendering" );
  ID3_TagHeader hdr;
  hdr.SetSpec(tag.GetSpec());
  hdr.SetExtended(tag.GetExtended());
  hdr.SetExperimental(tag.GetExperimental());
    
  // set up the encryption and grouping IDs

  // ...
  String frms;
  io::StringWriter frmWriter(frms);
  if (!tag.GetUnsync())
  {
    ID3D_NOTICE( "id3::v2::render(): rendering frames" );
    renderFrames(frmWriter, tag);
    hdr.SetUnsync(false);
  }
  else
  {
    ID3D_NOTICE( "id3::v2::render(): rendering unsynced frames" );
    io::UnsyncedWriter uw(frmWriter);
    renderFrames(uw, tag);
    uw.flush();
    ID3D_NOTICE( "id3::v2::render(): numsyncs = " << uw.getNumSyncs() );
    hdr.SetUnsync(uw.getNumSyncs() > 0);
  }
  size_t frmSize = frms.size();
  if (frmSize == 0)
  {
    ID3D_WARNING( "id3::v2::render(): rendered frame size is 0 bytes" );
    return;
  }
  
  // zero the remainder of the buffer so that our padding bytes are zero
  luint nPadding = tag.PaddingSize(frmSize);
  ID3D_NOTICE( "id3::v2::render(): padding size = " << nPadding );
  hdr.SetDataSize(frmSize + nPadding);
  
  hdr.Render(writer);

  writer.writeChars(frms.data(), frms.size());

  for (size_t i = 0; i < nPadding; ++i)
  {
    if (writer.writeChar('\0') == ID3_Writer::END_OF_WRITER)
    {
      break;
    }
  }
}

size_t ID3_TagImpl::Size() const
{
  if (this->NumFrames() == 0)
  {
    return 0;
  }
  ID3_TagHeader hdr;

  hdr.SetSpec(this->GetSpec());
  size_t bytesUsed = hdr.Size();
  
  size_t frameBytes = 0;
  for (const_iterator cur = _frames.begin(); cur != _frames.end(); ++cur)
  {
    if (*cur)
    {
      (*cur)->SetSpec(this->GetSpec());
      frameBytes += (*cur)->Size();
    }
  }
  
  if (!frameBytes)
  {
    return 0;
  }
  
  bytesUsed += frameBytes;
  // add 30% for sync
  if (this->GetUnsync())
  {
    bytesUsed += bytesUsed / 3;
  }
    
  bytesUsed += this->PaddingSize(bytesUsed);
  return bytesUsed;
}


void ID3_TagImpl::RenderExtHeader(uchar *buffer)
{
  if (this->GetSpec() == ID3V2_3_0)
  {
  }
  
  return ;
}


#define ID3_PADMULTIPLE (2048)
#define ID3_PADMAX  (4096)


size_t ID3_TagImpl::PaddingSize(size_t curSize) const
{
  luint newSize = 0;
  
  // if padding is switched off or there is no attached file
  if (! _is_padded || !this->GetPrependedBytes())
  {
    return 0;
  }
    
  // if the old tag was large enough to hold the new tag, then we will simply
  // pad out the difference - that way the new tag can be written without
  // shuffling the rest of the song file around
  if (this->GetPrependedBytes() && (this->GetPrependedBytes() >= curSize) && 
      (this->GetPrependedBytes() - curSize) < ID3_PADMAX)
  {
    newSize = this->GetPrependedBytes();
  }
  else
  {
    luint tempSize = curSize + ID3_GetDataSize(*this);
    
    // this method of automatic padding rounds the COMPLETE FILE up to the
    // nearest 2K.  If the file will already be an even multiple of 2K (with
    // the tag included) then we just add another 2K of padding
    tempSize = ((tempSize / ID3_PADMULTIPLE) + 1) * ID3_PADMULTIPLE;
    
    // the size of the new tag is the new filesize minus the audio data
    newSize = tempSize - ID3_GetDataSize(*this);
  }
  
  return newSize - curSize;
}