/*
* Entagged Audio Tag library
* Copyright (c) 2004-2005 Christian Laireiter <liree@web.de>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
package entagged.audioformats.asf.io;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.math.BigInteger;
import entagged.audioformats.asf.data.Chunk;
import entagged.audioformats.asf.data.EncodingChunk;
import entagged.audioformats.asf.data.GUID;
import entagged.audioformats.asf.util.Utils;
/**
* This class reads the chunk containing encoding data <br>
* <b>Warning:<b><br>
* Implementation is not completed. More analysis of this chunk is needed.
*
* @author Christian Laireiter
*/
public class EncodingChunkReader {
/**
* This reads the current data and interprets it as an encoding chunk. <br>
* <b>Warning:<b><br>
* Implementation is not completed. More analysis of this chunk is needed.
*
* @param raf
* Input source
* @param candidate
* Chunk which possibly contains encoding data.
* @return Encoding info. <code>null</code> if its not a valid encoding
* chunk. <br>
* @throws IOException
* read errors.
*/
public static EncodingChunk read(RandomAccessFile raf, Chunk candidate)
throws IOException {
if (raf == null || candidate == null) {
throw new IllegalArgumentException("Arguments must not be null.");
}
if (GUID.GUID_ENCODING.equals(candidate.getGuid())) {
raf.seek(candidate.getPosition());
return new EncodingChunkReader().parseData(raf);
}
return null;
}
/**
* Should not be used for now.
*
*/
protected EncodingChunkReader() {
// NOTHING toDo
}
/**
* see {@link #read(RandomAccessFile, Chunk)}
*
* @param raf
* input source.
* @return Enconding info. <code>null</code> if its not a valid encoding
* chunk. <br>
* @throws IOException
* read errors.
*/
private EncodingChunk parseData(RandomAccessFile raf) throws IOException {
EncodingChunk result = null;
long chunkStart = raf.getFilePointer();
GUID guid = Utils.readGUID(raf);
if (GUID.GUID_ENCODING.equals(guid)) {
BigInteger chunkLen = Utils.readBig64(raf);
result = new EncodingChunk(chunkStart, chunkLen);
// Can't be interpreted
/*
* What do I think of this data, well it seems to be another GUID.
* Then followed by a UINT16 indicating a length of data following
* (by half). My test files just had the length of one and a two
* bytes zero.
*/
raf.skipBytes(20);
/*
* Read the number of strings which will follow
*/
int stringCount = Utils.readUINT16(raf);
/*
* Now reading the specified amount of strings.
*/
for (int i = 0; i < stringCount; i++) {
result.addString(Utils.readCharacterSizedString(raf));
}
}
return result;
}
}