File	Doc	Category	Size	Date	Package
XingFrame.java	API Doc	Jaudiotagger 2.0.4	8299	Mon Sep 12 15:51:24 BST 2011	org.jaudiotagger.audio.mp3

XingFrame

• java.lang.Object

Fields Summary
private static final int	MPEG_VERSION_1_MODE_MONO_OFFSET
private static final int	MPEG_VERSION_1_MODE_STEREO_OFFSET
private static final int	MPEG_VERSION_2_MODE_MONO_OFFSET
private static final int	MPEG_VERSION_2_MODE_STEREO_OFFSET
private static final int	XING_HEADER_BUFFER_SIZE
private static final int	XING_IDENTIFIER_BUFFER_SIZE
private static final int	XING_FLAG_BUFFER_SIZE
private static final int	XING_FRAMECOUNT_BUFFER_SIZE
private static final int	XING_AUDIOSIZE_BUFFER_SIZE
public static final int	MAX_BUFFER_SIZE_NEEDED_TO_READ_XING
private static final int	BYTE_1
private static final int	BYTE_2
private static final int	BYTE_3
private static final int	BYTE_4
private static final byte[]	XING_VBR_ID Use when it is a VBR (Variable Bitrate) file
private static final byte[]	XING_CBR_ID Use when it is a CBR (Constant Bitrate) file
private ByteBuffer	header
private boolean	vbr
private boolean	isFrameCountEnabled
private int	frameCount
private boolean	isAudioSizeEnabled
private int	audioSize
private LameFrame	lameFrame

Constructors Summary

private XingFrame(ByteBuffer header) Read the Xing Properties from the buffer this.header=header; //Go to start of Buffer header.rewind(); //Set Vbr setVbr(); //Read Flags, only the fourth byte of interest to us byte flagBuffer[] = new byte[XING_FLAG_BUFFER_SIZE]; header.get(flagBuffer); //Read FrameCount if flag set if ((flagBuffer[BYTE_4] & (byte) (1)) != 0) { setFrameCount(); } //Read Size if flag set if ((flagBuffer[BYTE_4] & (byte) (1 << 1)) != 0) { setAudioSize(); } //TODO TOC //TODO VBR Quality //Look for LAME Header as long as we have enough bytes to do it properly if (header.limit() >= XING_HEADER_BUFFER_SIZE + LameFrame.LAME_HEADER_BUFFER_SIZE) { header.position(XING_HEADER_BUFFER_SIZE); lameFrame = LameFrame.parseLameFrame(header); }

Methods Summary
public final int	getAudioSize() return size of audio data in bytes return audioSize;
public final int	getFrameCount() return count of frames return frameCount;
public LameFrame	getLameFrame() return lameFrame;
public final boolean	isAudioSizeEnabled() return true if audioSize has been specified in header return isAudioSizeEnabled;
public final boolean	isFrameCountEnabled() return true if frameCount has been specified in header return isFrameCountEnabled;
public final boolean	isVbr() Is this XingFrame detailing a variable bit rate MPEG return return vbr;
public static java.nio.ByteBuffer	isXingFrame(java.nio.ByteBuffer bb, MPEGFrameHeader mpegFrameHeader) IS this a Xing frame param bb param mpegFrameHeader return true if this is a Xing frame //We store this so can return here after scanning through buffer int startPosition = bb.position(); //Get to Start of where Xing Frame Should be ( we dont know if it is one at this point) if (mpegFrameHeader.getVersion() == MPEGFrameHeader.VERSION_1) { if (mpegFrameHeader.getChannelMode() == MPEGFrameHeader.MODE_MONO) { bb.position(startPosition + MPEG_VERSION_1_MODE_MONO_OFFSET); } else { bb.position(startPosition + MPEG_VERSION_1_MODE_STEREO_OFFSET); } } //MPEGVersion 2 and 2.5 else { if (mpegFrameHeader.getChannelMode() == MPEGFrameHeader.MODE_MONO) { bb.position(startPosition + MPEG_VERSION_2_MODE_MONO_OFFSET); } else { bb.position(startPosition + MPEG_VERSION_2_MODE_STEREO_OFFSET); } } //Create header from here ByteBuffer header = bb.slice(); // Return Buffer to start Point bb.position(startPosition); //Check Identifier byte[] identifier = new byte[XING_IDENTIFIER_BUFFER_SIZE]; header.get(identifier); if ((!Arrays.equals(identifier, XING_VBR_ID)) && (!Arrays.equals(identifier, XING_CBR_ID))) { return null; } MP3File.logger.finest("Found Xing Frame"); return header;
public static org.jaudiotagger.audio.mp3.XingFrame	parseXingFrame(java.nio.ByteBuffer header) Parse the XingFrame of an MP3File, cannot be called until we have validated that this is a XingFrame return throws InvalidAudioFrameException XingFrame xingFrame = new XingFrame(header); return xingFrame;
private void	setAudioSize() Set size of AudioData byte frameSizeBuffer[] = new byte[XING_AUDIOSIZE_BUFFER_SIZE]; header.get(frameSizeBuffer); isAudioSizeEnabled = true; audioSize = (frameSizeBuffer[BYTE_1] << 24) & 0xFF000000 | (frameSizeBuffer[BYTE_2] << 16) & 0x00FF0000 | (frameSizeBuffer[BYTE_3] << 8) & 0x0000FF00 | frameSizeBuffer[BYTE_4] & 0x000000FF;
private void	setFrameCount() Set count of frames byte frameCountBuffer[] = new byte[XING_FRAMECOUNT_BUFFER_SIZE]; header.get(frameCountBuffer); isFrameCountEnabled = true; frameCount = (frameCountBuffer[BYTE_1] << 24) & 0xFF000000 | (frameCountBuffer[BYTE_2] << 16) & 0x00FF0000 | (frameCountBuffer[BYTE_3] << 8) & 0x0000FF00 | frameCountBuffer[BYTE_4] & 0x000000FF;
private void	setVbr() Set whether or not VBR, (Xing can also be used for CBR though this is less useful) //Is it VBR or CBR byte[] identifier = new byte[XING_IDENTIFIER_BUFFER_SIZE]; header.get(identifier); if (Arrays.equals(identifier, XING_VBR_ID)) { MP3File.logger.finest("Is Vbr"); vbr = true; }
public java.lang.String	toString() return a string representation return "xingheader" + " vbr:" + vbr + " frameCountEnabled:" + isFrameCountEnabled + " frameCount:" + frameCount + " audioSizeEnabled:" + isAudioSizeEnabled + " audioFileSize:" + audioSize;