Util/ApeReader.cs

   1 //
   2 // ApeReader.cs : Reads an Ape tag from the given stream
   3 //
   4 // Author:
   5 //              Raphaël Slinckx <raf.raf@wol.be>
   6 //
   7 // Copyright 2004 (C) Raphaël Slinckx (ported from http://entagged.sourceforge.net)
   8 //
   9
  10 //
  11 // Permission is hereby granted, free of charge, to any person obtaining a
  12 // copy of this software and associated documentation files (the "Software"),
  13 // to deal in the Software without restriction, including without limitation
  14 // the rights to use, copy, modify, merge, publish, distribute, sublicense,
  15 // and/or sell copies of the Software, and to permit persons to whom the
  16 // Software is furnished to do so, subject to the following conditions:
  17 //
  18 // The above copyright notice and this permission notice shall be included in
  19 // all copies or substantial portions of the Software.
  20 //
  21 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  22 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  23 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  24 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  25 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  26 // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  27 // DEALINGS IN THE SOFTWARE.
  28 //
  29
  30 using System;
  31 using System.IO;
  32 using System.Text;
  33 using System.Collections;
  34
  35 namespace Beagle.Util.AudioUtil {
  36
  37         public class ApeTagReader {
  38
  39                 private ASCIIEncoding ascii = new ASCIIEncoding ();
  40                 private UTF8Encoding utf = new UTF8Encoding ();
  41
  42                 public Tag Read (Stream fs)
  43                 {
  44                         Tag tag = new Tag ();
  45
  46                         //Check wether the file contains an APE tag--------------------------------
  47                         fs.Seek (-32, SeekOrigin.End);
  48
  49                         byte[] b = new byte[8];
  50                         fs.Read (b, 0, 8);
  51
  52                         string tagS = ascii.GetString (b, 0, 8);
  53                         if (tagS != "APETAGEX"){
  54                                 throw new Exception ("There is no APE Tag in this file");
  55                         }
  56                         //Parse the tag -)------------------------------------------------
  57                         //Version
  58                         b = new byte[4];
  59                         fs.Read (b, 0, 4);
  60                         int version = getNumber (b, 0, 3);
  61                         if (version != 2000) {
  62                                 throw new Exception ("APE Tag other than version 2.0 are not supported");
  63                         }
  64
  65                         //Size
  66                         b = new byte[4];
  67                         fs.Read (b, 0, 4);
  68                         int tagSize = getNumber (b, 0, 3);
  69
  70                         //Number of items
  71                         b = new byte[4];
  72                         fs.Read (b, 0, 4);
  73                         int itemNumber = getNumber (b, 0, 3);
  74
  75                         //Tag Flags
  76                         b = new byte[4];
  77                         fs.Read (b, 0, 4);
  78                         //TODO handle these
  79
  80                         fs.Seek (-tagSize, SeekOrigin.End);
  81
  82                         for (int i = 0; i < itemNumber; i++) {
  83                                 //Content length
  84                                 b = new byte[4];
  85                                 fs.Read (b, 0, 4);
  86                                 int contentLength = getNumber (b, 0, 3);
  87
  88                                 //Item flags
  89                                 b = new byte[4];
  90                                 fs.Read (b, 0, 4);
  91                                 //TODO handle these
  92                                 bool binary = ((b[0]&0x06) >> 1) == 1;
  93
  94                                 int j = 0;
  95                                 while (fs.ReadByte () != 0)
  96                                         j++;
  97                                 fs.Seek (-j-1, SeekOrigin.Current);
  98                                 int fieldSize = j;
  99
 100                                 //Read Item key
 101                                 b = new byte[fieldSize];
 102                                 fs.Read (b, 0, fieldSize);
 103                                 fs.ReadByte ();
 104                                 string field = ascii.GetString (b, 0, fieldSize);
 105
 106                                 //Read Item content
 107                                 b = new byte[contentLength];
 108                                 fs.Read (b, 0, contentLength);
 109                                 string content;
 110                                 if (!binary)
 111                                         content = utf.GetString (b, 0, contentLength);
 112                                 else
 113                                         content = ascii.GetString (b, 0, contentLength);
 114
 115                                 if (field.ToLower () == "title")
 116                                         tag.Title = content;
 117                                 else if (field.ToLower () == "artist")
 118                                         tag.Artist = content;
 119                                 else if (field.ToLower () == "album")
 120                                         tag.Album = content;
 121                                 else if (field.ToLower () == "year")
 122                                         tag.Year = content;
 123                                 else if (field.ToLower () == "comment") {
 124                                         tag.Comment = content;
 125                                 } else if (field.ToLower () == "track")
 126                                         tag.Track = content;
 127                                 else if (field.ToLower () == "genre")
 128                                         tag.Genre = content;
 129                         }
 130
 131                         return tag;
 132                 }
 133
 134                 //Computes a (end-start) bytes long number
 135                 private int getNumber (byte[] b, int start, int end)
 136                 {
 137                         int number = 0;
 138                         for (int i = 0; i< (end-start+1); i++) {
 139                                 number += ((b[start+i]&0xFF) << i*8);
 140                         }
 141
 142                         return number;
 143                 }
 144         }
 145 }