Android Open Source - vanilindy Ogg File

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License

The source code is released under:
Apache License
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Java Source Code

/*
 * Copyright (C) 2013 Adrian Ulrich <adrian@blinkenlights.ch>
 */*w  w  w  .j a v  a 2  s .  c o  m*/
 * 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 3 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, see <http://www.gnu.org/licenses/>. 
 */

package ch.blinkenlights.bastp;


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


public class OggFile extends Common {

  private static final int OGG_PAGE_SIZE    = 27;  // Static size of an OGG Page
  private static final int OGG_TYPE_COMMENT = 3;   // ID of 'VorbisComment's
  
  public OggFile() {
  }
  
  public HashMap getTags(RandomAccessFile s) throws IOException {
    long offset = 0;
    int  retry  = 64;
    HashMap tags = new HashMap();
    
    for( ; retry > 0 ; retry-- ) {
      long res[] = parse_ogg_page(s, offset);
      if(res[2] == OGG_TYPE_COMMENT) {
        tags = parse_ogg_vorbis_comment(s, offset+res[0], res[1]);
        break;
      }
      offset += res[0] + res[1];
    }
    return tags;
  }
  
  
  /* Parses the ogg page at offset 'offset' and returns
  ** [header_size, payload_size, type]
  */
  private long[] parse_ogg_page(RandomAccessFile s, long offset) throws IOException {
    long[] result   = new long[3];               // [header_size, payload_size]
    byte[] p_header = new byte[OGG_PAGE_SIZE];   // buffer for the page header 
    byte[] scratch;
    int bread       = 0;                         // number of bytes read
    int psize       = 0;                         // payload-size
    int nsegs       = 0;                         // Number of segments
    
    s.seek(offset);
    bread = s.read(p_header);
    if(bread != OGG_PAGE_SIZE)
      xdie("Unable to read() OGG_PAGE_HEADER");
    if((new String(p_header, 0, 5)).equals("OggS\0") != true)
      xdie("Invalid magic - not an ogg file?");
    
    nsegs = b2u(p_header[26]); 
    // debug("> file seg: "+nsegs);
    if(nsegs > 0) {
      scratch  = new byte[nsegs];
      bread    = s.read(scratch); 
      if(bread != nsegs)
        xdie("Failed to read segtable");
      
      for(int i=0; i<nsegs; i++) {
        psize += b2u(scratch[i]); 
      }
    }
    
    // populate result array
    result[0] = (s.getFilePointer() - offset);
    result[1] = psize;
    result[2] = -1;
    
    /* next byte is most likely the type -> pre-read */
    if(psize >= 1 && s.read(p_header, 0, 1) == 1) {
      result[2] = b2u(p_header[0]);
    }
    
    return result;
  }
  
  /* In 'vorbiscomment' field is prefixed with \3vorbis in OGG files
  ** we check that this marker is present and call the generic comment
  ** parset with the correct offset (+7) */
  private HashMap parse_ogg_vorbis_comment(RandomAccessFile s, long offset, long pl_len) throws IOException {
    final int pfx_len = 7;
    byte[] pfx        = new byte[pfx_len];
    
    if(pl_len < pfx_len)
      xdie("ogg vorbis comment field is too short!");
    
    s.seek(offset);
    s.read(pfx);
    
    if( (new String(pfx, 0, pfx_len)).equals("\3vorbis") == false )
      xdie("Damaged packet found!");
    
    return parse_vorbis_comment(s, offset+pfx_len, pl_len-pfx_len);
  }
  
};
Java Source Code List
