| 1 | package org.farng.mp3.id3; |
| 2 | |
| 3 | import org.farng.mp3.AbstractMP3FragmentBody; |
| 4 | import org.farng.mp3.InvalidTagException; |
| 5 | |
| 6 | import java.io.IOException; |
| 7 | import java.io.RandomAccessFile; |
| 8 | |
| 9 | /** |
| 10 | * Each ID3v2 frame contains a header and then the payload. This is the super class for the payload |
| 11 | * |
| 12 | * @author Eric Farng |
| 13 | * @version $Revision: 1.4 $ |
| 14 | */ |
| 15 | public abstract class AbstractID3v2FrameBody extends AbstractMP3FragmentBody { |
| 16 | |
| 17 | /** |
| 18 | * Creates a new AbstractID3v2FrameBody object. |
| 19 | */ |
| 20 | protected AbstractID3v2FrameBody() { |
| 21 | super(); |
| 22 | } |
| 23 | |
| 24 | /** |
| 25 | * Creates a new AbstractID3v2FrameBody object. |
| 26 | */ |
| 27 | protected AbstractID3v2FrameBody(final AbstractID3v2FrameBody copyObject) { |
| 28 | super(copyObject); |
| 29 | } |
| 30 | |
| 31 | public boolean equals(final Object obj) { |
| 32 | return obj instanceof AbstractID3v2FrameBody && super.equals(obj); |
| 33 | } |
| 34 | |
| 35 | protected int readHeader(final RandomAccessFile file) throws IOException, InvalidTagException { |
| 36 | final int size; |
| 37 | final byte[] buffer = new byte[3]; |
| 38 | if (has6ByteHeader()) { |
| 39 | // read the 3 byte size |
| 40 | file.read(buffer, 0, 3); |
| 41 | size = (int) (buffer[0] * Math.pow(2, 16) + buffer[1] * Math.pow(2, 8) + buffer[2]); |
| 42 | } else { |
| 43 | // read the 4 byte size |
| 44 | size = file.readInt(); |
| 45 | |
| 46 | // we need to skip the flag bytes; |
| 47 | file.skipBytes(2); |
| 48 | } |
| 49 | if (size == 0) { |
| 50 | throw new InvalidTagException("Found empty frame"); |
| 51 | } |
| 52 | if (size <= 0 || size > file.length()) { |
| 53 | throw new InvalidTagException("Invalid size for Frame Body"); |
| 54 | } |
| 55 | return size; |
| 56 | } |
| 57 | |
| 58 | protected void writeHeader(final RandomAccessFile file, final int size) throws IOException { |
| 59 | final byte[] buffer = new byte[3]; |
| 60 | if (has6ByteHeader()) { |
| 61 | // write the 3 byte size; |
| 62 | buffer[0] = (byte) ((size & 0x00FF0000) >> 16); |
| 63 | buffer[1] = (byte) ((size & 0x0000FF00) >> 8); |
| 64 | buffer[2] = (byte) (size & 0x000000FF); |
| 65 | file.write(buffer); |
| 66 | } else { |
| 67 | // write the 4 byte size; |
| 68 | file.writeInt(size); |
| 69 | |
| 70 | // need to skip 2 flag bytes |
| 71 | file.skipBytes(2); |
| 72 | } |
| 73 | } |
| 74 | } |