Posted by Martin Heffels on 07/11/06 09:30

On Tue, 11 Jul 2006 08:18:57 GMT, "PTravel" <ptravel@travelersvideo.com>
wrote:

>> Did you miss out that I said "You can answer that question based on your
>> own experience"?
>
>I have answered it based on my own experience: not one uncorrectable error
>in 200 hours.

Well there you go, a hard figure based on your own experience, and one
which will be applicable to 99% of the users of mini-DV. I'm glad the
occurence for you is so low. We are not all that lucky :-((

>I know that miniDV uses ECC. I said that in my first post. The number of
>corrected errors is irrelevant.

It is. The "100 drop-outs a minute" figure says that in your case there
were 1200000 errors in those 200 hours, with one uncorrecteable one, which
means an error rate of 0.0000000833%. Or in other figures that 1 in every
200 tapes is bad in such a way that it has drop-outs which _can't_ be
corrected. Now, how many people here have 200 tapes for private purpose?
Not a lot, so you would have to be unlucky to have bought that bad tape.
But, tv-stations and post-production shops, which run though 100's of tapes
a month, will hit upon the problematic tapes quite frequent.

>>>No need. Once more: D-25 video has better quality than DVD-compliant
>>>mpeg. Period.
>>
>> Not at the same bitrate.
>
>That's like saying apples are equal to oranges, except for the difference in
>peel, fruit, texture and taste. DVD-compliant mpeg doesn't have the same
>bit rate as D-25.

DVD-compliant doesn't. But that discussion deviated to the compression
quality and efficiency of DV25 vs MPEG2. And it still stays that if I
compress a regular video to MPEG2 of 8 MB/s or DV8 (which doesn't exist),
the quality of the MPEG2 material will be better.

>> That's what I said. Proved in yet another
>> SMPTE-article. And I think I also posted a link to a codec-quality
>> comparison which tells the same.
>
>Again, your comparing apples and horseflies. It doesn't matter which codec
>is better. What matters is whether the video quality of D-25 is better than
>DVD-compliant mpeg. It is, and it always will be.

Yes, I agree with that, never disagreed with it.

[...]
>I'm sure it is. So what? mpeg2, in its DVD-compliant flavor, produces
>poorer quality video than D-25.

Yes, you made your point :-)

>> I will make it even worse for you: even with corrected errors you get
>> generation loss. Because the errors can be corrected so _you_ don't see
>> them, but the bits are different from what they originally where, so you
>> have lost a generation.
>
>Now you've just re-defined corrected errors. Sorry, I'll stick with the
>definitions we've been using, i.e. there are two kinds of error correction,
>one that results in bit-accurate data, and one that interpolates and doesn't
>result in bit-accurate data. Or are you now claiming that all ECC results
>in interpolated, non-bit-accurate data?

No I am not claiming that. In my other posts I have listed the different
forms of error-correction which are used, so, also that erros can be
corrected to the correct-bit, based upon the Reed-Solomon mechanisms.

>That's right. And component is . . . analog. And firewire is . . .
>digital. So the question posed was: does digital result in greater
>generational loss than analog? And the answer, of course, is it does not,
>because there is no generational loss for digital. Did you have something
>in mind other than D-25 (or, for that matter, D-50? D-1?)

No, was solely thinking about D25. I thought I have answered that somewhere
as well: analogue generation-loss is worse than digital.

>Exactly. And what I would never do in my profession is present my
>unsupported belief as fact. See, what's interesting here, and as I've said
>several times, I'm perfectly willing to be persuaded that you and Richard
>are right. All it will take is a fact or two.

I agree, and I think the same. But for me there is in this case no need to
look up hard figures, because I speak from _my_ experience, which you
obviously don't have to believe.

>> 666 hours? Eeek :-)
>
>That's the math. Maybe there's a hidden message there.

Who knows!

>> But let me bring this forward again and again: errors
>> can be corrected without you noticing it, by borrowing or interpolating,
>> but they content of the bits has changed.
>
>I know. You've said it many times. And each time, my reply is the same:
>how often do corrected-by-borrowing-or-interpolating
>errors-so-that-I-wouldn't-notice-but-the-data-changed-anyway errors occur?
>Because if its the number in Richard's guestimate, then even the busiest,
>most hard-working pro in this newsgroup isn't going to hit one more than
>once or twice a year.

Looking at your quote from your experience, I would say they will hit upon
uncorrectable errors quite often.

>>>>>That means that 99.99999975% of the time, the data is accurate, i.e. a
>>>>>bit-for-bit copy.
>>>>
>>>> That is not a bit-for-bit copy, because that would be 100%!
>>>
>>>I'll tell you one thing that it's not, though: "generational loss."
>>
>> It _is_ generational loss, because you have something which is different
>> from the original.
>
>One 8-bit error for every 666 hours of video. That means 665 miniDV tapes
>would be pristine. How would you quantify that "generational loss"?

Let me point back to your "1 error in 200 hours". But fact is indeed, that
for now I just can't show any numbers which show how "un"-pristine this all
actually is.

cheers

-martin-
--
"If he can he'll smile 'cos he's a Royal Crocodile."

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