/** * 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; } } }