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In the Forum: Didital Things
In the Thread: A need for Resolution /Sampling Assessment Test
Post Subject: Well, we kind of 'have' a file Virginity Assessment TestPosted by Romy the Cat on: 10/9/2009

Not completely objective but still “some kind of test” for the bit’s resolution. For those of us who use Pacific Microsonics processors it is easy to see of the file was original. When pacific does A/D it injects the HDCD code. It does it in any sampling rate. The good part is that the HDCD code get injected into the very last 24th bit and any type of file manipulation, I mean ANY type, would imidetaly corrupt the last 24th bit and destroy the HDCD code. I do not even talk bout the sever dams of the file like change volume or apply ANY kind of pressing. Even if we take the raw 24Bit file from Pacific, record it into 32 bit and then just strip the last 8 bits then the HDCD code will be lost. So, the presents of the HDCD code is very much acid test for file virginity.

There is a glitch however on this “methodology”.

The first glitch is that the Assessment Test via HDCD code is not auditable assessment. To recognize the presents of the HDCD code we HDCD DAC with HDCD indication. Auditable the HDCD code is not detectable at high resolution formats. Although Mark Donahu, the Chief Mastering Engineer at Soundmirror, claimed some HDCD advantages at 88/24 in “spatial imaging and overall imaging acuity” due to the “optimize its own reconstruction filters” but it turned out to be just his fantasies. Even if I am wrong and Donahu is right and the differences with and without HDCD are auditable then it is not distinctive enough to be identifier for an objective file Assessment Test by hearing.

The second glitch is more severe that makes the HDCD Resolution Assessment Test not useful. Pacific Microsonics re-injects the HDCD in D-D operation. So, it would be perfectly possible for mastering engenders to take a raw Pacific file with HDCD code on the 24th bit, shit and piss on it as they usually do, convert it to 8bit and 22kB file and then, before the final release, to pass it via Pacific in D to D mode. The Pacific Microsonics will inject the code into the last available bit (16 th, 20th or 24th) and the destroyed file will look at the HDCD indicators as it was “virgin”.

I know it is too late to reinvent the HDCD format. Still, the HDCD has interface to forces the HDCD decoders do not read the HDCD code. It would be nice if the HDCD would have a flag differentiating between the “original HDCD” and “reapplied HDCD”.  If so then it would be VERY good identifier about the originally of the files.

Rgs, Romy the Cat

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