Posted by PTravel on 01/12/34 11:52

<mmaker@my-deja.com> wrote in message
news:1152543082.503878.45400@h48g2000cwc.googlegroups.com...
> ptravel@travelersvideo.com wrote:
>> Simply saying so doesn't make it so.
>
> Look, you can claim all you like the data dropouts don't happen on DV,
> but some of us have been working with DV for the best part of a decade,
> and have seen plenty of them. Which are we supposed to believe: your
> claims or our experience?

I didn't say they don't happen. I said that they're such a rare event that
considering them a source of generational loss is incorrect.

>
>> > > In the
>> > > 200-300 hours of digital video that I've shot, I've never had a
>> > > single
>> > > instance of drop-out -- not one.
>> > Really? Your deck actually tells you when it gets an uncorrectable
>> > error?
>> No -- drop out is obvious when it occurs.
>
> How? The only obvious dropouts are when a) the dropout is in the audio
> track, where the DV deck can't mask it and drops in a frame of silence
> instead or b) when there's too much motion in the frame for it to hide
> the dropout by replacing a video block with the same block from the
> previous frame. Otherwise you won't notice dropouts when they occur,
> but you've still lost data from the original file.

Decks may do this kind of correction, but I don't use one. I use an old
camcorder for transfer -- if there was drop out, there would be a noticeable
block of corruption on a single frame. Though I've not experienced any drop
out, I have had instances where there was a break in timecode because, for
example, I had removed the tape, then placed it back in and not bothered to
find the final frame. The break was obvious when I captured or tried to
view the tape.

>
>> > Or are you just guessing you've never had a dropout because you've
>> > never noticed it?
>> See above.
>
> Where you said nothing useful.
>
>> I think you'd be surprised by the result.
>
> No I wouldn't, because I know what the result would be.
>
>> I have no intention of
>> wasting that kind of time.
>
> Good for you. But if you're not willing to actually do the tests to
> determine the level of dropouts, no-one should be expected to believe
> you when you claim they're 'extremely rare'.

Have you done your "dupe a tape 100 times" test? Incidently, introduction
of drop out after 100 dupes would indicated a 1% failure rate for D-25. Do
you think that's right?

>
>> Nonetheless, drop out is not the same
>> thing as generational loss.
>
> No-one ever said it was.

Well, you did.
>
>> So what? How often is a hard drive read, versus tape? The recording
>> density is far greater for hard drives than tape.
>
> How is that even remotely relevant?

It makes the likelihood of drop out far greater.

>
> A hard disk is reliable because it's designed to pretty much guarantee
> reliable storage of data: if it gets a single random error it can read
> the block again and hopefully get the correct data the second time, and
> if it continually gets errors on the same block it can move the data
> elsewhere. A tape can't do anything like that, if a section of tape is
> bad, you're going to get dropouts because there's nowhere else for the
> camera to write the data and it can't go back and try to read the tape
> a second time.

Well, yes. The point, though, is that both hard drives and tape use ECC.

>
>> DV cameras don't replace drop-out with anything,
>
> Yes they do... you merely need to look at the playback of a section of
> tape with serious dropouts to see exactly what the camera is doing.
> Again, you're just proving that you don't know what you're talking
> about.
>
> Mark
>

[Back to original message]