[Flac] Checking file integrity

Brian Willoughby brianw at sounds.wa.com
Sun Apr 24 06:40:10 PDT 2011


On Apr 24, 2011, at 02:43, Anton Shepelev wrote:
> The  procedure  you  have described in your previous
> reply is quite complicated for an  automatic  check-
> ing.  Why  does FLAC calculate MD5 on the RAW uncom-
> pressed data?  If  it  were  using  compressed  data
> instead  the checking wouldn't require decompression
> and would be quicker: just calculate the hash on the
> binary  file  and  compare  it  against  the  stored
> value...

An MD5 on the compressed data would be different for every  
compression level, and potentially for every revision of the libFLAC  
coder.  In this case, the quicker solution is not the best.  There is  
only one MD5 hash for the uncompressed data, and it proves that you  
got back the original data without any loss, which is the whole point  
of FLAC.  In fact, the way it is implemented provides two features:  
It ensures that your FLAC file has not been corrupted, and it also  
ensures that you actually get back the original data without any loss.

p.s. scott has already provided the -t solution.

Brian Willoughby
Sound Consulting



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