/*
* Entagged Audio Tag library
* Copyright (c) 2003-2005 Raphael Slinckx <raphael@slinckx.net>
*
* 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 org.jaudiotagger.audio.mp3;
import org.jaudiotagger.audio.generic.Utils;
import org.jaudiotagger.tag.id3.valuepair.TextEncoding;
import java.nio.ByteBuffer;
import java.util.Arrays;
/**
* The first frame can sometimes contain a LAME frame at the end of the Xing frame
* <p/>
* <p>This useful to the library because it allows the encoder to be identified, full specification
* can be found at http://gabriel.mp3-tech.org/mp3infotag.html
* <p/>
* Summarized here:
* 4 bytes:LAME
* 5 bytes:LAME Encoder Version
* 1 bytes:VNR Method
* 1 bytes:Lowpass filter value
* 8 bytes:Replay Gain
* 1 byte:Encoding Flags
* 1 byte:minimal byte rate
* 3 bytes:extra samples
* 1 byte:Stereo Mode
* 1 byte:MP3 Gain
* 2 bytes:Surround Dound
* 4 bytes:MusicLength
* 2 bytes:Music CRC
* 2 bytes:CRC Tag
*/
public class LameFrame {
public static final int LAME_HEADER_BUFFER_SIZE = 36;
public static final int ENCODER_SIZE = 9; //Includes LAME ID
public static final int LAME_ID_SIZE = 4;
public static final byte[] LAME_ID = "LAME".getBytes();
private String encoder;
private byte vbrMethod;
private int lowpass;
private float replayGainPeak;
private short replayGainRadio;
private short replayGainAudiophile;
private byte encFlags;
private byte bitrate;
private int encDelay;
private int encPadding;
/**
* Initilise a Lame Mpeg Frame
*
* @param lameHeader
*/
private LameFrame(ByteBuffer lameHeader) {
encoder = Utils.getString(lameHeader, 0, ENCODER_SIZE, TextEncoding.CHARSET_ISO_8859_1);
vbrMethod = (byte) (lameHeader.get() & 0x0F);
lowpass = lameHeader.get() * 100;
replayGainPeak = lameHeader.getFloat();
replayGainRadio = lameHeader.getShort();
replayGainAudiophile = lameHeader.getShort();
encFlags = lameHeader.get();
bitrate = lameHeader.get();
byte[] delay = new byte[3];
lameHeader.get(delay);
encDelay = delay[0] << 4 | (delay[1] >> 4 & 0x0F);
encPadding = (delay[1] & 0x0F) << 8 | (delay[2] & 0xFF);
//TODO do the rest
}
/**
* Parse frame
*
* @param bb
* @return frame or null if not exists
*/
public static LameFrame parseLameFrame(ByteBuffer bb) {
ByteBuffer lameHeader = bb.slice();
byte[] id = new byte[LAME_ID_SIZE];
lameHeader.get(id);
if (Arrays.equals(id, LAME_ID)) {
lameHeader.position(lameHeader.position() - 4);
return new LameFrame(lameHeader);
}
lameHeader.position(lameHeader.position() - 3);
return null;
}
/**
* @return encoder
*/
public String getEncoder() {
return encoder;
}
public byte getVbrMethod() {
return vbrMethod;
}
public int getLowpass() {
return lowpass;
}
public float getReplayGainPeak() {
return replayGainPeak;
}
public short getReplayGainRadio() {
return replayGainRadio;
}
public short getReplayGainAudiophile() {
return replayGainAudiophile;
}
public byte getEncFlags() {
return encFlags;
}
public byte getBitrate() {
return bitrate;
}
public int getEncDelay() {
return encDelay;
}
public int getEncPadding() {
return encPadding;
}
}