[opendtv] Re: Time to give up on 1080i for football
- From: Tom Barry <trbarry@xxxxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Tue, 08 Dec 2009 17:49:35 -0500
Bert -
inline, again ...
Manfredi, Albert E wrote:
> Tom Barry wrote:
>
>
>> dan.grimes@xxxxxxxx wrote:
>>
>>> "If we are really to believe that 1080/60p takes up no more
>>> channel capacity than 720/60p, then we are also claiming that
>>> 720/60p takes up no more channel capacity than 480/60p, and
>>> by logical extension, 1080/60p takes up no more channel
>>> capacity than 480/60p." -Bert
>>>
>>> Your "If A=B and B=C then A=C" logic is infallible. But
>>> your premise that anyone thinks A=B is absurd.
>>>
>> I don't at all think A=B in that case.
>>
>> But, even if it did, that does not at all imply the second
>> step, B=C. Imagine the case where for some reason there was no
>> fixed overhead and yet NOTHING was ever encoded with an
>> effective source resolution greater than that of 720p. This
>> could happen because of poor cameras & telecines or simply
>> because everything in the world was for some reason brick
>> wall filtered to 720 rez, even if encoded at 1080p.
>>
>> In the above extreme case and without extra per block overhead
>> it could (almost) be claimed 1080 = 720. But that would still
>> say nothing about whether 720 = 480.
>>
>> So it was the second step of the logic I was disputing since
>> B=C appeared as an intermediate conclusion, not a premise.
>>
>
> Whoa, Tom, I think you missed the point of my original reply. It was meant to
> be a "reductio ad absurdum."
>
>
Yep. Even as a computer nerd I had eventually figured that out. But on
the last post I was replying to Dan. He had stated 'Your "If A=B and
B=C then A=C" logic is infallible'. I was pedantically pointing out
you had instead stated "If A=B then B=C and thus A=C". And that was
not the same thing. But I was just nit picking here.
> The comment has been made MORE than once, on this list, that 1080i is "less
> efficient" than 720p. Fine.
>
>
I believe 1080p is indeed more efficient than 1080i. But to me that
would just be in terms of bits/pixel (technically b/p/s). I'm don't
think bits / frame (or field) would also be smaller since the frames
have twice as many pixels. I have also seen that one stated but don't
believe it is true in general. Figures I've heard bandied about are
that interlace is less efficient but maybe only by about 10-15% or so.
> The argument has also been made more than once that because progressive is
> "more efficient," might as well code 1080/60p instead of 1080i. This is the
> kind of vague semantics that get people in trouble.
>
> THAT is what I was addressing.
>
>
Agreed. And for MPEG-2 ATSC now and going forward 1080i/30 works,
720p/60 works better, and 1080p/60 simply will not occur. Ever.
> Yes, 1080p is "more efficient" than 1080i by certain measures, but that's NOT
> to say that 1080/60p takes up less channel capacity than 1080i for the same
> quality images.
>
> Proof:
>
> Assume it is true that 1080/60p takes up equal or less channel capacity than
> 1080i, for same quality.
>
> We already know that 720p takes up similar or less channel capacity than
> 1080i for the same quality, right?
>
> So if 1080/60p takes less capacity than 1080i, and
> 720/60p takes less or similar capacity than 1080i,
>
> it MUST follow that 720p/60p takes up less or equal capacity than 1080/60p.
>
> Which is absurd. (Modulo the bit about prefiltering to dumb down 1080p.)
>
> Bert
>
>
Uhh, I think only the conclusions of reductio ad absurdum arguments are
supposed to be absurd. But the proof is not needed since I think we are
mostly on the same page now. So I'll shut up. ;-)
- Tom
>
> ----------------------------------------------------------------------
> You can UNSUBSCRIBE from the OpenDTV list in two ways:
>
> - Using the UNSUBSCRIBE command in your user configuration settings at
> FreeLists.org
>
> - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
> unsubscribe in the subject line.
>
>
>
----------------------------------------------------------------------
You can UNSUBSCRIBE from the OpenDTV list in two ways:
- Using the UNSUBSCRIBE command in your user configuration settings at
FreeLists.org
- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
unsubscribe in the subject line.
Other related posts:
