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Didital Things
Topic: A need for Resolution /Sampling Assessment Test

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Posted by Romy the Cat on 10-06-2009

In the time of silver photography, when we shoot on E6 film, we use grayscales on the first image to let the print shops to correct chromic aberration of film, development or lighting. Looking at the amount of BS the today is going on with high-res files I suspects that this BS will widening with increase popularity of high-res. So, what I think need to be invented is some king of digital watermark that would allow us - the users - to hear the objective amount of bids and rate. Here is how I see it shall be invented.

During recording process the recording engineers before music starts, right along with the microphone feed record a resolution /sampling assessment signal. This signal is engendered in such way that change of sampling rate of resolution destroyed the signal. Furthermore the record resolution/sampling assessment signal being played at proper resolution and sampling shell produce some kind of auditable reference. Think about the LP test record when a voice is counting frequency and the specially made track measures the tonearm resonance frequency. Something like this shall be designed for identification of resolution and sampling rate. I know, it is hard to record the upper bites above 20 bit, I do not know, I am not engineer – they shall think about it.

What I do know is that what I but a file I would like to know how it was recorded and what kind rate and resolution transformations it what over while it reaches me. I think the company that do it first would get a lot of very positive publicity if their files will be opening with audible Resolution /Sampling Assessment Test

The caT

Posted by Romy the Cat on 10-09-2009

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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