/**
* @param startByte
* @param endByte
* @return
* @throws Exception
* @return true if all the bytes between in the file between startByte and endByte are null, false
* otherwise
*/
private boolean isFilePortionNull(int startByte, int endByte) throws IOException {
logger.config("Checking file portion:" + Hex.asHex(startByte) + ":" + Hex.asHex(endByte));
FileInputStream fis = null;
FileChannel fc = null;
try {
fis = new FileInputStream(file);
fc = fis.getChannel();
fc.position(startByte);
ByteBuffer bb = ByteBuffer.allocateDirect(endByte - startByte);
fc.read(bb);
while (bb.hasRemaining()) {
if (bb.get() != 0) {
return false;
}
}
} finally {
if (fc != null) {
fc.close();
}
if (fis != null) {
fis.close();
}
}
return true;
}
/**
* Creates a new MP3File dataType and parse the tag from the given file Object, files can be
* opened read only if required.
*
* @param file MP3 file
* @param loadOptions decide what tags to load
* @param readOnly causes the files to be opened readonly
* @throws IOException on any I/O error
* @throws TagException on any exception generated by this library.
* @throws org.jaudiotagger.audio.exceptions.ReadOnlyFileException
* @throws org.jaudiotagger.audio.exceptions.InvalidAudioFrameException
*/
public MP3File(File file, int loadOptions, boolean readOnly)
throws IOException, TagException, ReadOnlyFileException, InvalidAudioFrameException {
RandomAccessFile newFile = null;
try {
this.file = file;
// Check File accessibility
newFile = checkFilePermissions(file, readOnly);
// Read ID3v2 tag size (if tag exists) to allow audioHeader parsing to skip over tag
long tagSizeReportedByHeader = AbstractID3v2Tag.getV2TagSizeIfExists(file);
logger.config("TagHeaderSize:" + Hex.asHex(tagSizeReportedByHeader));
audioHeader = new MP3AudioHeader(file, tagSizeReportedByHeader);
// If the audio header is not straight after the end of the tag then search from start of file
if (tagSizeReportedByHeader != ((MP3AudioHeader) audioHeader).getMp3StartByte()) {
logger.config("First header found after tag:" + audioHeader);
audioHeader = checkAudioStart(tagSizeReportedByHeader, (MP3AudioHeader) audioHeader);
}
// Read v1 tags (if any)
readV1Tag(file, newFile, loadOptions);
// Read v2 tags (if any)
readV2Tag(file, loadOptions, (int) ((MP3AudioHeader) audioHeader).getMp3StartByte());
// If we have a v2 tag use that, if we do not but have v1 tag use that
// otherwise use nothing
// TODO:if have both should we merge
// rather than just returning specific ID3v22 tag, would it be better to return v24 version ?
if (this.getID3v2Tag() != null) {
tag = this.getID3v2Tag();
} else if (id3v1tag != null) {
tag = id3v1tag;
}
} finally {
if (newFile != null) {
newFile.close();
}
}
}
/**
* Regets the audio header starting from start of file, and write appropriate logging to indicate
* potential problem to user.
*
* @param startByte
* @param firstHeaderAfterTag
* @return
* @throws IOException
* @throws InvalidAudioFrameException
*/
private MP3AudioHeader checkAudioStart(long startByte, MP3AudioHeader firstHeaderAfterTag)
throws IOException, InvalidAudioFrameException {
MP3AudioHeader headerOne;
MP3AudioHeader headerTwo;
logger.warning(
ErrorMessage.MP3_ID3TAG_LENGTH_INCORRECT.getMsg(
file.getPath(),
Hex.asHex(startByte),
Hex.asHex(firstHeaderAfterTag.getMp3StartByte())));
// because we cant agree on start location we reread the audioheader from the start of the file,
// at least
// this way we cant overwrite the audio although we might overwrite part of the tag if we write
// this file
// back later
headerOne = new MP3AudioHeader(file, 0);
logger.config("Checking from start:" + headerOne);
// Although the id3 tag size appears to be incorrect at least we have found the same location
// for the start
// of audio whether we start searching from start of file or at the end of the alleged of file
// so no real
// problem
if (firstHeaderAfterTag.getMp3StartByte() == headerOne.getMp3StartByte()) {
logger.config(
ErrorMessage.MP3_START_OF_AUDIO_CONFIRMED.getMsg(
file.getPath(), Hex.asHex(headerOne.getMp3StartByte())));
return firstHeaderAfterTag;
} else {
// We get a different value if read from start, can't guarantee 100% correct lets do some more
// checks
logger.config(
(ErrorMessage.MP3_RECALCULATED_POSSIBLE_START_OF_MP3_AUDIO.getMsg(
file.getPath(), Hex.asHex(headerOne.getMp3StartByte()))));
// Same frame count so probably both audio headers with newAudioHeader being the first one
if (firstHeaderAfterTag.getNumberOfFrames() == headerOne.getNumberOfFrames()) {
logger.warning(
(ErrorMessage.MP3_RECALCULATED_START_OF_MP3_AUDIO.getMsg(
file.getPath(), Hex.asHex(headerOne.getMp3StartByte()))));
return headerOne;
}
// If the size reported by the tag header is a little short and there is only nulls between
// the recorded value
// and the start of the first audio found then we stick with the original header as more
// likely that currentHeader
// DataInputStream not really a header
if (isFilePortionNull((int) startByte, (int) firstHeaderAfterTag.getMp3StartByte())) {
return firstHeaderAfterTag;
}
// Skip to the next header (header 2, counting from start of file)
headerTwo =
new MP3AudioHeader(
file, headerOne.getMp3StartByte() + headerOne.mp3FrameHeader.getFrameLength());
// It matches the header we found when doing the original search from after the ID3Tag
// therefore it
// seems that newAudioHeader was a false match and the original header was correct
if (headerTwo.getMp3StartByte() == firstHeaderAfterTag.getMp3StartByte()) {
logger.warning(
(ErrorMessage.MP3_START_OF_AUDIO_CONFIRMED.getMsg(
file.getPath(), Hex.asHex(firstHeaderAfterTag.getMp3StartByte()))));
return firstHeaderAfterTag;
}
// It matches the frameCount the header we just found so lends weight to the fact that the
// audio does indeed start at new header
// however it maybe that neither are really headers and just contain the same data being
// misrepresented as headers.
if (headerTwo.getNumberOfFrames() == headerOne.getNumberOfFrames()) {
logger.warning(
(ErrorMessage.MP3_RECALCULATED_START_OF_MP3_AUDIO.getMsg(
file.getPath(), Hex.asHex(headerOne.getMp3StartByte()))));
return headerOne;
}
/// Doesnt match the frameCount lets go back to the original header
else {
logger.warning(
(ErrorMessage.MP3_RECALCULATED_START_OF_MP3_AUDIO.getMsg(
file.getPath(), Hex.asHex(firstHeaderAfterTag.getMp3StartByte()))));
return firstHeaderAfterTag;
}
}
}
