Mp3 Book Helper

SFV/SV/PAR Generation and SFV/SV/PAR Tests

.SFV (Simple File Verificator) files are used to ensure that files are not corrupt and not missing. These files contain CRC32 (Cyclic Redundancy Checksum) of files and file size in comments section.

.PAR/P01/./P?? (Parity Archive Volume Set) files are used for data recovery. Mp3BookHelper do not recover files in current version but uses this files in the same way as SFV for fast test for completeness and correct size of mp3 files. If you need to recover files use PAR clients http://parchive.sourceforge.net/

.SV (Sound Verification Checksum) MP3BookHelper now able to calculate CRC for non-tag parts of a mp3 file (non-tag-CRC, Audio Only) and store this information in .SV files. Using that, you can change tags with any program you want, and then verify that that the sound in the mp3 has not changed to be sure that the program you are using has not corrupted the sound.

Also you could repost renamed and changed tags files to news group and ppl should be able to verify new set of files using previously posted .SV files. .SV stands for Sound Verification and is effectively list of CRC for non-tag parts of a mp3 file. non-tag-CRC in .SV would be changed if you normalize Mp3 files, change Encoding and so on. non-tag-CRC should work correctly with any changes in ID3v1, ID3v2 and Lyrics tags -> non-tag-CRC would remain the same.

MP3BookHelper could create special files .SV with non-tag-CRC also non-tag-CRC could be added to comments portion of .sfv files created by Mp3BH.

How does the non-tag-CRC (mp3-crc) get calculated? The tool is searching for the first valid frame, this is the start of Mp3Data. Then it finds ID3v1 and Lyrics Tags at the end of file. End of Mp3Data is where this Tags if any begin. Standard crc32 of the mp3data calculated and used. If there is a truncated frame at the end of the file it gets into calculated CRC so if you fix this later in any tool Mp3BH would show that the file is changed.

To create the Simple File Verify (SFV) Checksum files after you updated Tags and/or renamed files press F8 or select 'Create SFV/SV' from menu. If you change you mp3 files after SFV was created you will get warning message when you try to close program or clear file list.

If you get the files over Internet than it is a good idea to test if you got all files and they are not corrupted using 'Files' tab of main window.

'SFV/PAR:' would show SFV files from mp3 files directory. You could test your MP3 files against any of these files. Results would be shown in 'Test result' column.

PAR files and some SFV files have file size in comments section. Mp3BookHelper will use this information to quickly compare your mp3 files size with information available. 'Size OK', 'File Truncated' or 'Extra data' would be shown base on this data.

If files have been renamed program could try guess and match you existing files against information in SFV. 'Renamed' would be shown. Currently only spaces and punctuations removed from file names could be detected automatically.

'Test' will calculate CRC checksum and/or MD5 hash of your mp3 files and compare them with information in selected SFV and PAR files. Test result would be: Good = 'CRC OK' or Corrupted = 'CRC Mismatch'.

TSIZ-support. When a new ID3v2-Tag is saved, then there is always a TSIZ-frame saved. This frames stores the length of the MP3-file without the ID3v2 and ID3v1 header. If this frame exists, then the stored one will be used. If it does not exist then it would be created on first tag update. It is never changed! In the tests you see when the TSIZ-info doesn't match the actual size. Mp3BookHelper will use this information to quickly compare your mp3 files size with information available. '(TSIZ)Size OK', '(TSIZ)File Truncated' or '(TSIZ)Extra data' would be shown base on this data.

Other tests results are:

'Error'Error reading file
'Duplicate'File with the save CS was found in the file list of in duplicates DB
'MpegOK'Only SV checksum match.
'CRC Mismatch'Non of checksums CRC, MD5 or SV match
'File Missing'Mp3/Ogg file included in SFV/PAR file not found
'File Not Loaded'File exists but not loaded to Mp3BookHelper. Use 'Load Remaining' button to load it(them) to file list
'No CRC Data'Your mp3 file do not have corresponding SFV or PAR file
CRC ?there are CRC or MD5 data for your file but you need to run 'Test SFV' to get results.

If you have more than one SFV or PAR file in directory test result will show number before any result. This number indicates which SFV or PAR file has been used for tests. If mp3 file present in two files then best match result would be shown. Best is Good = 'CRC OK'. Check and Uncheck PAR/SFV files to compare your files with selected files. No need to run 'Test' again MP3BookHelper remember files checksum in memory.

In some case Mp3BookHelper is able to find missing files even without SVF. Currently file names enumeration is used. For example is loaded files are abook_01-06.mp3, abook_02-06.mp3, abook_04-06.mp3, abook_05-06.mp3. Than it will show warning that file abook_03-05.mp3 is missing. It will not show warning for file abook_06-06.mp3

File filters 'Loaded & Missing' and 'Missing only' should be used to show missing files in 'Files' tab.

MP3BookHelper work under assumption that all files in one directory are related and belong to one book (Album).

After tests MP3BookHelper will create hidden .sfvt file in each directory. .sfvt contains the list of tested files so Mp3BH don't need to re-test files again. Mp3BH reads these files automatically. Automatic creation of .sfvt files could be disabled in options: File->Options->Other->Keep tested files DB [x] creates files .sfvt

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