/**
* 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;
}
}
}
