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EAC use regarding .WAV compression


kgturner

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hello, all! my name is kevin and i'm a short time lurker, first time poster.

 

i am in the process of ripping my cd collection to .wav files so that i can do a head to head between my SB3 / 47 Labs Shigaraki DAC & my 47 Labs Shigaraki Transport / DAC combo. i'm using EAC to rip my cd's to my hard drive. i typically rip them in burst mode and test the CRC to ensure that the "Read CRC" and "Test CRC" are "OK" which they are 99% of the time.

 

i have noticed, however, that at the very bottom of the EAC dialog box, it gives a readout of the cd "size". for instance, the cd i have in my drive now is listed as 376.44 MB, but the anticipated output .wav file for the disc is 376.32 MB. however, when i look out the "Size" and "Compressed Size" columns, they usually match. however, sometimes the "Size" column will read (for instance) 41.15 MB for a song while the "Compressed Size" column will read 41.09 MB. where does this .06 MB go?

 

granted, the missing amounts are usually a very negliglbly small amount, but something in the back of mind tells me that any amount of data missing is a bad thing. can somebody explain why there is usually a small amount of data missing from the .wav files? thanks much.

 

kevin t

 

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Good question Kevin. Hopefully someone here will no the answer. My only guess would be that this has something to do with a file allocation table. Maybe the size is different on the disc v. the disk because they use different file allocation tables.

 

I could be 100% wrong here. I am just guessing.

 

Can anyone help Kevin?

 

Founder of Audiophile Style

UPDATED: My Audio Systems -> https://audiophile.style/system

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Hi Kevin and welcome to non-lurking status!

 

You can find out most of what you are looking for here (wikipedia can be pretty good and definitely quick):

http://en.wikipedia.org/wiki/Red_Book_(audio_CD_standard)

 

The data that is present on the CD itself that is missing when you rip down to the essential sound files for use on a computer sound player are indeed sort of like the file allocation database used to manage HD data. There is more to it than that, but for this discussion that will hopefully suffice. It isn't actual sound data, and isn't needed for our purposes on the computer - relative and equivalent FAT files are generated by your computer instead but are not part of the actual audio files themselves, just like those on the CD aren't part of the audio itself-. Here is a relevant excerpt from the (short but referenced) wiki article:

 

On the disc, the data is stored in sectors of 2352 bytes each, read at 75 sectors per second. Onto this the overhead of EFM, CIRC, L2 ECC, and so on, is added, but these are not typically exposed to the application reading the disc.

 

Hope this helps.

 

markr

 

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