[opendtv] Re: A detail in the history of video standards
- From: Craig Birkmaier <craig@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Fri, 2 Sep 2005 09:19:02 -0400
At 4:01 AM -0700 9/2/05, Ron Economos wrote:
>If by "refined", you mean motion vector resolution, then both MPEG-1
>and MPEG-2 provide 1/2 pel vectors (1/2 pel is optional in MPEG-1
>and mandatory in MPEG-2).
>
>If you mean more modes available for better prediction, then all the
>new modes in MPEG-2 (field prediction in frame pictures, 16x8 and
>dual-prime) are field based.
>
>When coding progressive_sequence = 1 in MPEG-2 (for 720p), motion
> prediction is exactly the same as MPEG-1 with 1/2 pel vectors.
Fair enough. I guess you got me on this one.
>
>You can stick your head in the sand regarding interlace, but this
>is to nobodys advantage. Look what happened to SMPTE 421M
>(VC-1). They tossed in interlace at the last minute and managed
>to create an incredibly obtuse bitstream syntax. The SMPTE 421M
>(VC-1) specification is twice as many pages as H.264, and does less.
>
I am the last one to stick my head in the sand regarding interlace.
There is absolutely NO NEED to have interlaced in a digital
television system. The proper place to deal with interlaced receivers
is in the decoder, where it is a trivial matter to re-interlace and
filter properly so the source does not flicker. The proper place to
de-interlace is BEFORE the emission encoder so that you can use the
very best algorithms to do it properly. You then can encode the
source to maximize detail for progressive displays, and simply filter
out the extra details for interlaced displays. Adding all of the
complexity to encode interlace had prolonged the use of interlaced
acquisition by at least one and possibly two decades., which
coincidentally is about the duration of the IP that was created to
co-opt MPEG-2.
You can stick your head in the sand and tell me that this was not
possible when MPEG-2 was created, but you will just wind up with a
mouthful of sand.
Regards
Craig
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