[opendtv] Re: Time to give up on 1080i for football
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: "opendtv@xxxxxxxxxxxxx" <opendtv@xxxxxxxxxxxxx>
- Date: Tue, 8 Dec 2009 11:50:52 -0600
Dan Grimes wrote:
> Again, I agree that pre-filtering the material to render it
> the same as 720P is not a real gain. However, I do not think
> that pre-filtering is the only way one can achieve the
> compression needed to get 1080/60P to the target bit-rate.
> There are other ways to increase "efficiency", that is, the
> ability to get better picture quality for the same bit-rate.
> There are many techniques, especially the change in algorithms,
> that can improve picture quality while reducing bit rate, even
> while using the same encoding standard.
Not sure I understand your last sentence. Changing the compression algorithm
means NOT using the same encoding standard.
But sure, that aside, no argument. You can increase the size of the GOP, you
can dynamically vary that, you can tell the actors to move slowly, etc. Lots of
techniques. All else equal, though, you can get better picture quality with
1080/60p than with 720/60p, but it takes greater channel capacity. And trying
to squeeze 1080/60p down will reduce its image quality, to the point where it
may look no better than 720/60p.
And I agree with Tom that there will be overhead involved in the 1080p option
that will ultimately require some amount of waste compared with 720p, when
trying to limit the two to the same restricted channel.
Conversely, I watched Univision last night for a short time. They only transmit
one 480i channel in the multiplex (and, surprise, one subchannel just set up,
but with no info on it yet). EXCELLENT quality. Looks very much the same as SD
programs upconverted to 720p or 1080i in other stations. Looks nothing like
many of the overly compressed SD subchannels you often see.
Bert
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