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Posted by M.I.5 on 01/18/07 14:07
"Joshua Zyber" <joshzyber@comcast.net> wrote in message
news:9pCdnTRxFaP27zLYnZ2dnUVZ_oupnZ2d@comcast.com...
> "M.I.5" <no.one@no.where.NO_SPAM.co.uk> wrote in message
> news:45af285e$1_1@glkas0286.greenlnk.net...
>> You are quoting out of context. On a CRT display it provides a very
>> obvious benefit even for interlaced source material. On a plasma display
>> it also provides a very obvious benefit even for interlaced source
>> material.
>>
>> However, on an LCD display, it makes no difference *for interlaced source
>> material* (we were specifically discussing DVD at the time) - which is
>> what I said.
>
> Why would an LCD be any difference than a plasma or progressive-capable
> CRT in this regard? Are you just pulling stuff out of your ass now or
> what?
>
Because of the relatively long time lag of the LCD elements. It makes no
perceptable visual diffeence if you write to the odd lines of the display
and then the even, or write to the whole display sequentially.
>> There is no way that conversion to progressive can alter the fact that
>> the odd lines occur in a time frame one fiftieth of a second earlier than
>> the even lines.
>
> Film-based content on DVD is stored in 720x480 frames with 2:3 reverse
> field cadence headers that instruct the MPEG decoder how to interlace them
> for output. The interlaced fields from each original frame do not come
> from different moments in time. With proper 3:2 deinterlacing, the
> original frames can be reconstructed in their original form.
>
You are trying to obfuscate the point by switching systems. Only Mickey
Mouse television systems have to do anything remotely like 3:2 pulldown just
to get film material to work.
We were discussing 720x576 pixel DVDs in which film originated material is
stored in the form that one film frame occupies both the odd and even
frames, but that is only because the film frame covers a time frame of one
twenty-fifth of a second*. But in video originated frames, the odd lines
contains information that occurs one fiftieth of a second before the
corresponding even line. Converting the output to progressive scan cannot
change that.
*Film for TV is shot at 25 frames per second. Cinema film is run 4% fast.
> This is of course different than how video-based content is stored on DVD,
> but we weren't talking about that. You specifically referenced a feature
> film's end credits.
>
No, feature film end credits was mentioned but I refered to both methods of
originating DVD material.
>> Of course for progressive source material then once again there is an
>> obvious benefit - but we weren't discussing that context.
>
> As a matter of fact, we were.
No we weren't.
We're discussing DVDs, which are not progresive scan?
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