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Guest Message by DevFuse

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who says no 1080P broadcasts soon?


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26 replies to this topic

#21 OFFLINE   skwayb

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Posted 14 December 2007 - 04:14 PM

Can someone explain why 1080p needs more bandwidth than 1080i. Both have 1080 lines of 1920 pixels. Both send 30 complete pictures per second so the same amount of data is sent in 1/30 of a second.

--- CHAS


I is for interlace so only the even number of 1920x540 lines are sent in one 1/60th of a second and then the odd number of 1920x540 lines are sent in the next 1/60th of second. Not all 1920x1080 are sent at one time. So half the bandwidth is needed for a 1080i vs 1080p image.

This explains it better.

http: //techdigs.net/content/view/53/42/

...Ads Help To Support This SIte...

#22 OFFLINE   John in Georgia

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Posted 14 December 2007 - 04:55 PM

http://www.afterdawn...chive/11874.cfm

Just thought I'd share this finally, if this go through ok, XstreamHD will give some x-tream competition for sure in the near future............


Wonder why this isn't being "unveiled" at the National Association of Broadcasters (NAB) instead of at the Consumer's Electronics Show (CES)?

#23 OFFLINE   Stewart Vernon

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Posted 14 December 2007 - 06:37 PM

Can someone explain why 1080p needs more bandwidth than 1080i. Both have 1080 lines of 1920 pixels. Both send 30 complete pictures per second so the same amount of data is sent in 1/30 of a second.

--- CHAS


Your question is incomplete.

1080p at 30 fps would be exactly the same as 1080i at 60 fps (since the interlaced frames are half the image)... but this isn't the only kind of 1080p.

The spec also has 1080p at 24 fps, which actually would be less bandwidth than 1080i... so that could be done with the current technology and space if they wanted to for films.

But the folks who want 1080p really are wanting 1080p at 60 fps... which would be twice the available/current bandwidth of 1080i at 60 fps... and that cannot be done at all via OTA. Via satellite/cable it could be done, but would cut by half the bandwidth available for channels.

-- My cat's breath smells like cat food.


#24 OFFLINE   HIPAR

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Posted 14 December 2007 - 07:32 PM

...

But the folks who want 1080p really are wanting 1080p at 60 fps... which would be twice the available/current bandwidth of 1080i at 60 fps...


That makes sense.

--- CHAS
But I don't want to go among mad people

#25 OFFLINE   P Smith

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Posted 14 December 2007 - 09:47 PM

That's old mode - 1080p60, now with new 120 Hz HD TV we want 1080p120 ! :)

#26 OFFLINE   soloredd

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Posted 15 December 2007 - 12:32 PM

Blah.

Good luck to these people staying afloat. HD customers in the overall picture account for very little. Those who are coming into HD see a huge difference from SD to HD but to expect them to then go from 720p/1080i to 1080p and find it worth it?? HA!

1080p should have been started from the get-go. In my opinion, it's too late to start pushing it out now. The next gen of high-definition programming will come along.

#27 OFFLINE   Stewart Vernon

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Posted 15 December 2007 - 02:25 PM

1080p should have been started from the get-go. In my opinion, it's too late to start pushing it out now. The next gen of high-definition programming will come along.


I agree with you on that point. I wish the OTA folks had gotten together and with the frequency changes and all with some of the spectrum being sold in a couple of years.. I wish that they had also taken the opportunity to re-define the channel bandwidth for digital OTA, so that in 2009 they could switchover and have more bandwidth per channel to be able to broadcast 1080p at 60 fps if needed.

It's also a shame, but nothing we can do about it at this point... that MPEG2 is locked into ATSC because with MPEG4 OTA could perhaps squeeze more in there too... but so many people would be stuck with non-MPEG4 HDTVs with built-in tuners that it would be a nightmare. So while satellite and cable can shift to MPEG4 for better bandwidth usage, OTA will be stuck with MPEG2 for the long haul.

-- My cat's breath smells like cat food.





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