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Posted by PTravel on 07/13/06 16:44
"Toby" <kymarto123@ybb.ne.jpp> wrote in message
news:44b5b15e$0$65941$bb4e3ad8@newscene.com...
>
> "PTravel" <ptravel@ruyitang.com> wrote in message
> news:4hfsbtF1rcvsvU1@individual.net...
>>
>> "Richard Crowley" <richard.7.crowley@intel.com> wrote in message
>> news:e8ucis$8o5$1@news01.intel.com...
>>> "PTravel" wrote ...
>>>> We're still talking about apples and oranges -- data reconstructed
>>>> using ECC is accurate and bit-for-bit what was recorded (or supposed to
>>>> have been recorded).
>>>
>>> No. That is the description of how ECC works for computer
>>> data. There is another MAJOR error recovery layer used by
>>> audio CDs, DVDs, DVD tape, etc. It is how they manage to
>>> be cost effective.
>>>
>>> Audio/video data that cannot be accurately *corrected* gets
>>> *mitigated* by extrapolation. This is the factor that is present
>>> in audio and video digital recording but NOT in computer data
>>> recording. It probably comes into play more often than we think,
>>> but if it is good enough we don't notice. But multiple repetitions
>>> of it amount to something approaching "generation loss".
>>
>> Can you site me to something that says how often this happens? I've
>> never heard of DV video transfers being described as anything other than
>> lossless.
>>
>>>
>>>> Replacing pixels (or scan lines or averaging blocks) results in lost
>>>> data.
>>>
>>> I think you have that backwards. Replacing pixels, etc. is one
>>> of the major migitating actions taken as a result of lost data.
>>
>> I meant that the resulting data is not the same as the original, hence
>> there is data lost. But how often does this happen?
>
> This reminds me of a story. How often do you think earthquakes happen in
> Japan? Once a month? Once a week? We recently did a doco about earthquakes
> here and visited one of their seismo centers. It turns out that the rate
> of measurable earthquakes is about 100 an hour.
>
> Do you see what I am getting at?
Yes, which is exactly what I've been getting at. Borrowing Martin's
terminology, what is the ratio of mitigated errors to fully-corrected
errors? If it's comparable to the ratio of major earthquakes in Japan
versus small tremors that no one notices, then we're looking at Richard's
guestimate that works out to 1 mitigated error per 666 hours of video. With
that kind of rate, miniDV is, for all intents and purposes, lossless.
However, we remain in the realm of speculation -- without hard data, this is
all pointless, and I'll stand by my position, i.e. there is no generation
loss for D-25 transfers.
>
> Toby
>
>
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