Posted by Toby on 03/13/06 08:35

<Acurajustin1978@hotmail.com> wrote in message
news:1141920918.830713.320660@e56g2000cwe.googlegroups.com...
>
> Frank wrote:
>> On 9 Mar 2006 06:44:50 -0800, in 'rec.video.production',
>> in article <PAL to NTSC no Quality Loss on DVD?>,
>> Acurajustin1978@hotmail.com wrote:
>>
>> >I downloaded a British TV show in HDTV and it was in PAL.
>>
>>
>> Not to be picky, but if it was HD (high definition), either 720p or
>> 1080i, then it wasn't PAL, as the terms PAL, NTSC, and SECAM apply
>> only to SD (standard definition) video.
>>
>> HD video, however, does retain the old SD video frame rates, so if it
>> originated in the U.K., then it would most likely have a frame rate of
>> 25 frames per second. Likewise, if it originated in the U.S., it would
>> most likely have a frame rate of (approximately) 29.97 frames per
>> second (actually 60/1.001 fields per second if it was interlaced).
>>
>> You probably already know this. I'm posting it just for the sake of
>> those who may not.
>>
>> Regards,
>>
>> --
>> Frank, Independent Consultant, New York, NY
>> [Please remove 'nojunkmail.' from address to reply via e-mail.]
>> Read Frank's thoughts on HDV at http://www.humanvalues.net/hdv/
>
>
> My mistake, Its actually PDTV.
> http://en.wikipedia.org/wiki/PDTV
>
> My curiosity has to do with frame rates. Why couldn't they perfect
> that back in the 80's and early 90's with VHS?
> The quality on this (Dr. Who s01e01 and 2.) Couldn't they use the same
> technique with analog formats?

Analog formats are a whole different kettle of fish. When color TV came out
they had to find a way of squeezing the chroma information into the very
limited bandwidth that had been allotted to B&W broadcast channels. It was
really shoehorned in there, and in fact PAL was an evolutionary step forward
from NTSC which locked the subcarrier phase (in my limited understanding).
The decision was made to go for more resolution at lower frame rate as well,
so you have 625 lines at 25 fps, instead of the lower resolution of NTSC
(525) at the higher nominal frame rate of 30 fps (actually 29.97)--this was
again a choice based on the limited bandwidth in use at the time.

Digital has changed all that--it's all in the D/A conversion. I've heard
that not all DVD players are happy about outputting NTSC from PAL DVDs, but
apparently some do it quite well.

Toby

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