Posted by Joshua Zyber on 01/09/07 00:13

"M.I.5�" <no.one@no.where.NO_SPAM.co.uk> wrote in message
news:45a23d0b$1_1@glkas0286.greenlnk.net...
>> The original resolution of film can't be measured because it's a
>> photochemical process, not an electronic one. However, once
>> transferred to DVD, both film and video have the exact same
>> resolution: 720x480 pixels (or 720x576 for PAL).
>
> Yes, but so what?

You claimed that "video" DVDs have more resolution than "film" DVDs,
which is utter nonsense.

>> All DVDs have the same measurable resolution. Don't confuse
>> resolution with sharpness; they are not the same thing. As far as not
>> being able to compare the sharpness of two different sources, you
>> could say the same thing about any two productions photographed
>> differently than one another, regardless of format. Movie X can be
>> sharper than Movie Y simply because that's the way they were shot.
>> Has nothing to do with film or video.
>
> But it is an inherent feature of the digitalisation process that when
> you move from the analogue domain to the digital domain, each pixel of
> the digital domain gets its infomation from an correspondingly larger
> area of the analogue source.

Obviously.

> Although the physical number of pixels
> is fixed, the circle of confusion (to misuse an analogue term) is
> larger than one pixel

Misuing an analog term is putting it lightly. The film source does not
contain pixels. Therefore, there is no "circle of confusion" larger than
pixels in the source.

> (and is totally dependant mainly on the source
> material, but also on how good the conversion process is), thus
> diluting the real resolution.

Diluting the real resolution of the film source, yes. Diluting the
resolution available on DVD, not at all.

DVD is capable of diplaying 720x576 pixels (to use PAL since that's your
country's chosen format). Whether that DVD is mastered from a
higher-quality source or from a source originally shot at 720x576
pixels, the end result will always be a DVD image of 720x576 pixels.
What is so difficult to understand about that?

You're arguing that mastering the disc from a higher-quality source will
result in worse picture quality than if you had mastered from a
lower-quality source. That's patently absurd!

> Obviously a digital video source will retain its full resolution,

In your argument, it would only retain its full resolution if that
original resolution were 720x576 pixels. What about content shot on HD
video and downgraded to DVD?

>> Oh good lord. The DVD may be interlaced, but the fields can be
>> reconstructed into whole video frames on a progressive scan screen.
>> That's the whole point of progressive scan. Please read this:
>>
>> http://www.hometheaterhifi.com/volume_7_4/dvd-benchmark-part-5-progressive-10-2000.html
>
> The arguments in that cite are valid only when the video system is
> progressive scan from start to finish. If the source material is
> interlaced, then converting it to progressive, still means that the
> odd numbered lines occur in a time frame one fiftieth of second
> earlier than the even numbered lines. Displaying interlaced source
> material on an LCD TV doesn't look any different than if the DVD
> player is set to convert to progressive. On a CRT TV there are
> considerable advantages from the flicker reduction, but this is
> countered because twice the bandwidth is required for the video
> content. This is one of the reasons interlaced video replaced
> progressive (or sequential as it was called when it was abandoned in
> 1936).

You use a lot of technical jargon that would make a layman think you
knew what you're talking about, but it's becoming quite clear that your
ideas are rooted in an antiquated understanding of how video works.

I would recommend that you sit down and actually read the entire article
that I linked above, specifically the sections titled NTSC Telecine,
Progressive Scan, and Re-Interleaving 24fps Film.

After that, read this:

http://en.wikipedia.org/wiki/Telecine#Reverse_telecine_.28a.k.a._IVTC.2Finverse_telecine.29

Here's a relevant excerpt:

"On DVDs, telecined material may be either hard telecined, or soft
telecined. In the hard-telecined case, video is stored on the DVD at the
playback framerate (29.97 frames/sec for NTSC, 25 frames/sec for PAL),
using the telecined frames as shown above. In the soft-telecined case,
the material is stored on the DVD at the film rate (24 or 23.976
frames/s) in the original progressive format, with special flags
inserted into the MPEG-2 video stream that instruct the DVD player to
repeat certain fields so as to accomplish the required pulldown during
playback. Progressive scan DVD players additionally offer output at 480p
by using these flags to duplicate frames rather than fields.

NTSC DVDs are often soft telecined, although lower-quality
hard-telecined DVDs exist. In the case of PAL DVDs using 2:2 pulldown,
the difference between soft and hard telecine vanishes, and the two may
be regarded as equal. In the case of PAL DVDs using 2:3 pulldown, either
soft or hard telecining may be applied."

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