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/*
* Copyright (C) 2013 Adrian Ulrich <adrian@blinkenlights.ch>
*
* 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 github.daneren2005.dsub.util.tags;
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);
}
};
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