Android Open Source - FPlayAndroid Metadata Extractor

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The source code is released under:
Copyright (c) 2013-2014, Carlos Rafael Gimenes das Neves All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the followin...
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Java Source Code

//
// FPlayAndroid is distributed under the FreeBSD License
////from  w ww.  j  a  v  a2  s  .  c om
// Copyright (c) 2013-2014, Carlos Rafael Gimenes das Neves
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this
//    list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright notice,
//    this list of conditions and the following disclaimer in the documentation
//    and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
// ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// The views and conclusions contained in the software and documentation are those
// of the authors and should not be interpreted as representing official policies,
// either expressed or implied, of the FreeBSD Project.
//
// https://github.com/carlosrafaelgn/FPlayAndroid
//
package br.com.carlosrafaelgn.fplay.playback;

import java.io.IOException;
import java.io.RandomAccessFile;
import java.util.Locale;

import br.com.carlosrafaelgn.fplay.list.FileSt;

public final class MetadataExtractor {
  private static final int FIELD_COUNT = 6;
  public static final int TITLE = 0;
  public static final int ARTIST = 1;
  public static final int ALBUM = 2;
  public static final int TRACK = 3;
  public static final int YEAR = 4;
  public static final int LENGTH = 5;
  
  private static final int ALL_B = 0x3f;
  private static final int ALL_BUT_LENGTH_B = 0x1f;
  private static final int TITLE_B = 0x01;
  private static final int ARTIST_B = 0x02;
  private static final int ALBUM_B = 0x04;
  private static final int TRACK_B = 0x08;
  private static final int YEAR_B = 0x10;
  private static final int LENGTH_B = 0x20;
  
  private static String readV2Frame(RandomAccessFile f, int frameSize, byte[][] tmpPtr) throws IOException {
    if (frameSize < 2) {
      f.skipBytes(frameSize);
      return null;
    }
    final int encoding = f.read();
    frameSize--; //discount the encoding
    if (encoding < 0 || encoding > 3) {
      f.skipBytes(frameSize);
      return null;
    }
    byte[] tmp = tmpPtr[0];
    if (frameSize > tmp.length) {
      tmp = new byte[frameSize + 16];
      tmpPtr[0] = tmp;
    }
    f.readFully(tmp, 0, frameSize);
    //according to http://developer.android.com/reference/java/nio/charset/Charset.html
    //the following charsets are ALWAYS available:
    //ISO-8859-1
    //US-ASCII
    //UTF-16
    //UTF-16BE
    //UTF-16LE
    //UTF-8
    String ret = null;
    switch (encoding) {
    case 0: //ISO-8859-1
      ret = new String(tmp, 0, frameSize, "ISO-8859-1");
      break;
    case 1: //UCS-2 (UTF-16 encoded Unicode with BOM), in ID3v2.2 and ID3v2.3
    case 2: //UTF-16BE encoded Unicode without BOM, in ID3v2.4
      ret = new String(tmp, 0, frameSize, "UTF-16");
      break;
    case 3: //UTF-8 encoded Unicode, in ID3v2.4
      //BOM
      ret = ((tmp[0] == 0xef && tmp[1] == 0xbb && tmp[2] == 0xbf) ?
          new String(tmp, 3, frameSize - 3, "UTF-8") :
          new String(tmp, 0, frameSize, "UTF-8"));
      break;
    }
    return ((ret != null && ret.length() == 0) ? null : ret);
  }
  
  private static String[] extractID3v1(RandomAccessFile f, int found, String[] fields, byte[] tmp) {
    try {
      f.seek(f.length() - 128);
      f.readFully(tmp, 0, 128);
      if (tmp[0] != 0x54 ||
        tmp[1] != 0x41 ||
        tmp[2] != 0x47) //TAG
        return fields;
      //struct _ID3v1 {
      //public:
      //  char title[30];
      //  char artist[30];
      //  char album[30];
      //  char year[4];
      //  char comment[28];
      //  unsigned char zeroByte; //If a track number is stored, this byte contains a binary 0.
      //  unsigned char track; //The number of the track on the album, or 0. Invalid, if previous byte is not a binary 0.
      //  unsigned char genre; //Index in a list of genres, or 255
      //} tag;
      int i, c;
      if ((found & TITLE_B) == 0) {
        i = 3;
        c = 0;
        while (c < 30 && tmp[i] != 0) {
          c++;
          i++;
        }
        if (c != 0)
          fields[MetadataExtractor.TITLE] = new String(tmp, 3, c, "ISO-8859-1");
      }
      if ((found & ARTIST_B) == 0) {
        i = 3 + 30;
        c = 0;
        while (c < 30 && tmp[i] != 0) {
          c++;
          i++;
        }
        if (c != 0)
          fields[MetadataExtractor.ARTIST] = new String(tmp, 3 + 30, c, "ISO-8859-1");
      }
      if ((found & ALBUM_B) == 0) {
        i = 3 + 30 + 30;
        c = 0;
        while (c < 30 && tmp[i] != 0) {
          c++;
          i++;
        }
        if (c != 0)
          fields[MetadataExtractor.ALBUM] = new String(tmp, 3 + 30 + 30, c, "ISO-8859-1");
      }
      if ((found & YEAR_B) == 0) {
        i = 3 + 30 + 30 + 30;
        c = 0;
        while (c < 4 && tmp[i] != 0) {
          c++;
          i++;
        }
        if (c != 0)
          fields[MetadataExtractor.YEAR] = new String(tmp, 3 + 30 + 30 + 30, c, "ISO-8859-1");
      }
      if ((found & TRACK_B) == 0 && tmp[128 - 3] == 0 && tmp[128 - 2] != 0)
        fields[MetadataExtractor.TRACK] = Integer.toString((int)tmp[128 - 2] & 0xff);
    } catch (Throwable ex) {
      //ignore all exceptions while reading ID3v1, in favor of
      //everything that has already been read in ID3v2
    }
    return fields;
  }
  
  private static String[] extractID3v2Andv1(RandomAccessFile f, byte[][] tmpPtr) throws IOException  {
    //struct _ID3v2TagHdr {
    //public:
    //  unsigned int hdr;
    //  unsigned char hdrRev;
    //  unsigned char flags;
    //  unsigned char sizeBytes[4];
    //} tagV2Hdr;
    
    //readInt() reads a big-endian 32-bit integer
    final int hdr = f.readInt();
    if ((hdr & 0xffffff00) != 0x49443300) //ID3
      return null;
    final int hdrRev = f.read();
    final int flags = f.read();
    final int sizeBytes0 = f.read();
    final int sizeBytes1 = f.read();
    final int sizeBytes2 = f.read();
    final int sizeBytes3 = f.read();
    int size = ((flags & 0x10) != 0 ? 10 : 0) + //footer presence flag
    (
      (sizeBytes3 & 0x7f) |
      ((sizeBytes2 & 0x7f) << 7) |
      ((sizeBytes1 & 0x7f) << 14) |
      ((sizeBytes0 & 0x7f) << 21)
    );
    if ((hdr & 0xff) > 2 || hdrRev != 0) { //only rev 3 or greater supported
      //http://id3.org/id3v2.3.0
      //http://id3.org/id3v2.4.0-structure
      //http://id3.org/id3v2.4.0-frames
      final String[] fields = new String[FIELD_COUNT];
      int found = 0;
      while (size > 0 && found != ALL_B) {
        //struct _ID3v2FrameHdr {
        //public:
        //  unsigned int id;
        //  unsigned int size;
        //  unsigned short flags;
        //} frame;
        final int frameId = f.readInt();
        final int frameSize = f.readInt();
        //skip the flags
        f.readShort();
        if (frameId == 0 || frameSize <= 0 || frameSize > size)
          break;
        switch (frameId) {
        case 0x54495432: //title - TIT2
          if ((found & TITLE_B) == 0) {
            fields[TITLE] = readV2Frame(f, frameSize, tmpPtr);
            if (fields[TITLE] != null)
              found |= TITLE_B;
          } else {
            f.skipBytes(frameSize);
          }
          break;
        case 0x54504531: //artist - TPE1
          if ((found & ARTIST_B) == 0) {
            fields[ARTIST] = readV2Frame(f, frameSize, tmpPtr);
            if (fields[ARTIST] != null)
              found |= ARTIST_B;
          } else {
            f.skipBytes(frameSize);
          }
          break;
        case 0x54414c42: //album - TALB
          if ((found & ALBUM_B) == 0) {
            fields[ALBUM] = readV2Frame(f, frameSize, tmpPtr);
            if (fields[ALBUM] != null)
              found |= ALBUM_B;
          } else {
            f.skipBytes(frameSize);
          }
          break;
        case 0x5452434b: //track - TRCK
          if ((found & TRACK_B) == 0) {
            fields[TRACK] = readV2Frame(f, frameSize, tmpPtr);
            if (fields[TRACK] != null)
              found |= TRACK_B;
          } else {
            f.skipBytes(frameSize);
          }
          break;
        case 0x54594552: //year - TYER
          if ((found & YEAR_B) == 0) {
            fields[YEAR] = readV2Frame(f, frameSize, tmpPtr);
            if (fields[YEAR] != null)
              found |= YEAR_B;
          } else {
            f.skipBytes(frameSize);
          }
          break;
        case 0x54445243: //Recording time - TDRC
          if ((found & YEAR_B) == 0) {
            fields[YEAR] = readV2Frame(f, frameSize, tmpPtr);
            if (fields[YEAR] != null) {
              if (fields[YEAR].length() > 4)
                fields[YEAR] = fields[YEAR].substring(0, 4);
              found |= YEAR_B;
            }
          } else {
            f.skipBytes(frameSize);
          }
          break;
        case 0x544c454e: //length - TLEN
          if ((found & LENGTH_B) == 0) {
            fields[LENGTH] = readV2Frame(f, frameSize, tmpPtr);
            if (fields[LENGTH] != null)
              found |= LENGTH_B;
          } else {
            f.skipBytes(frameSize);
          }
          break;
        default:
          f.skipBytes(frameSize);
          break;
        }
        size -= (10 + frameSize);
      }
      //try to extract ID3v1 only if there are any blank fields
      return (((found & ALL_BUT_LENGTH_B) != ALL_BUT_LENGTH_B) ? extractID3v1(f, found, fields, tmpPtr[0]) : fields);
    }
    return null;
  }
  
  public static String[] extract(FileSt file, byte[][] tmpPtr) {
    int i = file.path.lastIndexOf('.');
    if (i < 0)
      return null;
    final String ext = file.path.substring(i + 1).toLowerCase(Locale.US);
    //the only two formats supported for now... I hope to add ogg soon ;)
    if (!ext.equals("mp3") && !ext.equals("aac"))
      return null;
    RandomAccessFile f = null;
    try {
      f = ((file.file != null) ? new RandomAccessFile(file.file, "r") : new RandomAccessFile(file.path, "r"));
      return extractID3v2Andv1(f, tmpPtr);
    } catch (Throwable ex) {
    } finally {
      if (f != null) {
        try {
          f.close();
        } catch (Throwable ex2) {
        }
      }
    }
    return null;
  }
}
Java Source Code List
