I
DO like his thoroughness... but, of course, the real conclusion was obvious from the start.
And, hopefully, a few imaginary oil-snakes will sleep better this night because of it.
The give-away is about three sentences in on the manufacturer's claims...
"The CD player's Error Correction is
NOT a solution for the problem of light scattering".
This is entirely correct... or entirely incorrect... depending on how you look at it.
(The error correction is only a solution for problems that actually exist.)
Out of quite a few hundred CDs I've ripped, using a computer, where a checksum for each file was verified against a database...
I've seen exactly
TWO "unrepairable digital errors" (that's out of about 5,000 tracks).
In
BOTH cases the errors were present on the pressing master itself (as proven by the fact that they were present on multiple copies of the same disc).
(This means that all of the others were able to read perfectly - with zero unrecoverable errors.)
----------------
The data on a CD is digital data.
The
ONLY thing that would be a problem would be if that data was being read incorrectly - with errors.
If there were errors due to light scattering then the Error Correction
WOULD solve them by correcting the errors.
However, if there are no errors due to light scattering, then the Error Correction will not be correcting the errors that aren't there.
Therefore, depending on the actual situation, either there are no errors to begin with, or there are errors, and the error correction will correct them.
The reality is that most CD players have three levels of error correction...
There are two layers of digital error correction - which can provide a
PERFECT correction of most data errors.
(In which case there are
NO ERRORS in the resulting data.)
There is also a third level - interpolation - which is unable to provide a perfect correction.
(But that is really only used for major errors - like big scratches - of, to quote the spec, "holes over about 2 mm in diameter".)
But what about jitter?
ALL CD players read the data from the disc
INTO A BUFFER.
The data is then clocked from the buffer to the output.
Therefore the jitter at the output depends solely on the clock used to read the data out from the buffer.
As the fellow who did the video commented...
You might theoretically imagine that a disc with more errors "could make the CD player work harder"...
And that this "could cause it to have more jitter while correcting more errors"...
But nobody has ever shown this to be true for any player I know of.
------------------------
Now, to be fair, there are three situations where this device might
POSSIBLY theoretically offer some benefit.
(Assuming that it could be shown to offer even a miniscule improvement in reduction of "extraneous light" - which I doubt.)
Those would be:
- a CD that was so badly damaged that it was "borderline unreadable"
- a CD player that was so badly designed or defective that it was "borderline broken"
- an older CD player that was "borderline unable to read some CD-R type discs" (some of which do actually exist)
However note that a far better solution to all of those really rare but legitimate issues would be a new CD player.
