HydrogenAudio

Hydrogenaudio Forum => Scientific Discussion => Topic started by: FeliksKhozikov on 2019-12-07 23:51:50

Title: What does the CRC of a CD mean?
Post by: FeliksKhozikov on 2019-12-07 23:51:50
I have been looking at this cue tools database (http://db.cuetools.net/) and saw it has a CRC for each album and each tack.  What is it the CRC of.  Is it the CRC of the PCM samples or the raw data on the CD? (Which red book has a special compression format right?)  So could the CRC on that site be used to verify WAV files or only CDs?

If it's the format of the PCM samples do they need to be signed little endian to calculate the CRC?

Also, why is there so many different CRC's of the same album.  I looked at an album that had over 10 different entries of it all with different CRC numbers.
Title: Re: What does the CRC of a CD mean?
Post by: Roseval on 2019-12-08 10:15:23
Cyclic Redundancy Check is a trick to verify if the bits are read correctly.
You have a number on the CD
You apply a calculation to the bits
The result of the calculation and this number should be the same.
If not, part of the data (or the number itself) is mangled.
https://en.wikipedia.org/wiki/Cyclic_redundancy_check
Title: Re: What does the CRC of a CD mean?
Post by: kode54 on 2019-12-08 22:51:42
The CRC is applied to the audio data, not to the subchannel or other raw data.
Title: Re: What does the CRC of a CD mean?
Post by: greynol on 2019-12-09 00:36:01
The raw audio data. It does not include the wav header either.
Title: Re: What does the CRC of a CD mean?
Post by: korth on 2019-12-09 05:00:09
Some reading material
http://cue.tools/wiki/CUETools_Database
https://hydrogenaud.io/index.php?topic=79882.0
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