Hi Matt,
Thanks for restoring my faith in reality :)
We are (thankfully) not (generally) involed in 30fps-based frame rates in
Europe. Nevertheless, I would like to think that I still understand the
technicalities.
Your email gives me faith that a drunk Limey can still understand what's
going on in the nicely-agreed-format that is HD ;-)
Cheers,
Tone :)
ps let's not even start talking about HDV...
> Tony, that's what bugs me about using 1080i as a conventional way of
> referring to 59.94 interlaced fields. In fact when Sony invented HDCAM and
> the F500 it was basically a glorified D-Beta machine. At the time (and
> maybe
> still?) nobody could get a VTR to have enough bandwidth to store
> progressive
> 1920x1080 frames at 60fps which would be referred to as 1080P/60. So what
> Sony did was split the frame in half (odd and even lines) and record the
> first part on tape as field one and the second part as field two, hence
> "PsF" which means Progressive, Segmented Frames. Yes, it is interlaced on
> the tape so, I'm assuming, a lot of the same SD electronics and circuits
> could be used (not sure about that, just guessing). All HDCAM is 1080i,
> not
> 1080P even if you are working at 23.976 or 25. That's why its important to
> say PsF at the end AND to know that the format you are working in is 1080i
> and not 720P. So yes, 23.976PsF HDCAM is still 1080i and yes it is
> interlaced, technically, on the tape, yes. DOES THIS MATTER? You ask?
> Well,
> again, I like to be specific and avoid confusion so yes I think it matters
> very much. To use convention just makes the somewhat elaborate and
> confusing
> issue even more difficult. Try explaining all this to a non-technical
> presentation person in charge of purchasing and broadcasting shows!
>
> ps, when we eventually do get a 1080P tape format this will become even
> more
> important since you could really have 1080/59.94P and 1080/59.94i which
> would be half the temporal information and both still 1080x1920.
>
> Regards,
> Matt <stickler> Sherman.
>
>
> -----Original Message-----
> From: tony(at)hdheaven.co.uk [mailto:tony(at)hdheaven.co.uk]
> Sent: Sunday, August 28, 2005 5:46 AM
> To: DS(at)Softimage.COM
> Subject: Re: 1080i format question
>
> Hi Guys,
>
> Surely the "i" at the end of 1080i means "Interlaced" doesn't it? Which
> would differentiate it, for instance from 1080PsF.
>
> In other words, 1080 specifies the line count, i means interlaced, and
> then other information is requred to specify frame rate?
>
> So, 24P couldn't be called 1080i.
>
> Or have I completely misundertood something here?
>
> Cheers,
> Tone :)
>
>
>>
>> Mathew Sherman wrote:
>>
>>> Yet again I must remind everyone that saying "1080i" does not have
>>> anything to do with frame rate. People are getting confused when
>>> people tell them "we need 1080i" that it somehow precludes them from
>>> working at 24PsF. But the only thing truly that 1080i means (in this
>>> case I am referring to the HDNet spec) is that they do not want 720P
>>> originals. Sony HDCAM is a 1080i format regardless of what frame rate
>>> you are using. 24P is also 1080i and that is exactly what HDNet means.
>>> They don't like DVCPRO-HD since it's low bit rate (100Mbps) and is a
>>> 720P format (natively).
>>>
>>> In terms of what to do for a possible film-out well definitely working
>>> progressive will help the film look better, however these days there
>>> are such good de-interlacing tools that I bet one would have a hard
>>> time telling the difference between 59.94i (proper term) or 23.976PsF
>>> on the cinema screen once all is said and done, properly.
>>>
>> Sorry to disagree Matt but in the US 1080i has become synonymous with
>> 59.94 fields. Mark Cuban was involved in a discussion on the Telecine
>> Internet Group last year on this topic. He was quite adamant that the
>> research they've done on viewer preferences were so strongly in favor of
>> the higher frame rate that they chose to require that for delivery. I'm
>> not surprised since Mark Cuban is so involved with sports broadcasting
>> and the higher temporal resolution makes a difference. I happen to
>> prefer 720p for sports for the same reason - disclaimer: I'm ex-ABC
>> engineering.
>> If you're planning a film out there is a big advantage to working in 24p
>> (again, common usage in the US translates to 1080psf(at)23.97 - even for
>> film jobs you'd need to specify true 24p if you didn't want 23.97psf!).
>> Yes, there are de-interlace tools but it doesn't look the same and we've
>> been through it on numerous projects.
>>
>> --
>> Richard Torpey
>> VP Engineering
>> Rhinoceros/MultiVideo Group
>> 50 East 42 Street
>> New York, NY 10017
>> (212) 986-1577
>> (212) 986-3833 fax
>> (212) 692-4465 direct
>>
>>
>>
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