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  Reply # 156176 12-Aug-2008 08:56
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amphibem:

I agree, that is a bit annoying. Regarding hiccups, are others getting the occasional pauses? It was particularily bad during the cycling yesterday.


Those dropouts were caused by signal lost from the camera bikes following the even. With digital feeds you just get a freeze frame rather than static and picture breakup as you did with analog feeds..




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Old3eyes


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  Reply # 156236 12-Aug-2008 11:38
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I've seen some pixellation on the HD feeds, picture mometarily breaks up around fast moving areas etc, could just be bugs in my drivers? I've never seen this in normal programming - the feed is constant 720p? so not sure why the olympics HD signal is any different, just moving from upscaled to native. Anyway, still enjoying it, it's a total feast of sport. Beach vollyball looks real hot in HD, as will the pole vaulting :-)

 
 
 
 


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  Reply # 156240 12-Aug-2008 11:44
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ajst2duk: I've seen some pixellation on the HD feeds, picture mometarily breaks up around fast moving areas etc, could just be bugs in my drivers? I've never seen this in normal programming - the feed is constant 720p? so not sure why the olympics HD signal is any different, just moving from upscaled to native. Anyway, still enjoying it, it's a total feast of sport. Beach vollyball looks real hot in HD, as will the pole vaulting :-)


I have seen that breakup too, not only on my box but when I was wondering around Harvey Norman. They had I think Samsung TV's I was watching playing the Olympics with the built-in HD receiver and there was noticable pixalation occuring, particularily on skin tones. Saw it on a couple of TV's, saw it is definitely a feed problem.

On a side note, they had two TVs out front displaying Freeview HD; a 32" of HDMI and a 37" off component. I don't know if the component was showing actual HD but the quality was terrible! The colours where washed out, there was bad gosting, it was worse than most analogue signals. So don't know if it was a problem with the particular box or TV but seemed a bit of a worry to me!

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  Reply # 156251 12-Aug-2008 12:28
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amphibem:
On a side note, they had two TVs out front displaying Freeview HD; a 32" of HDMI and a 37" off component. I don't know if the component was showing actual HD but the quality was terrible! The colours where washed out, there was bad gosting, it was worse than most analogue signals. So don't know if it was a problem with the particular box or TV but seemed a bit of a worry to me!


I run my HD STB over component and HDMI.  I can't see any difference between either..  maybe something with HN setup..




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Old3eyes


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  Reply # 156276 12-Aug-2008 14:07
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A lot of those shops daisy chain TV's and dumb things like that. So the pictures can be real bad. Never been into a Dick Smith store yet with the TV's showing the image in the correct aspect ratio.





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  Reply # 156339 12-Aug-2008 17:11
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andrewcnz: A lot of those shops daisy chain TV's and dumb things like that. So the pictures can be real bad. Never been into a Dick Smith store yet with the TV's showing the image in the correct aspect ratio.


In this case I had a quick look behind and it was direct connection from the box the TV, no splitters. Looked like they had used the more expensive brownish cables too for what its worth.

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  Reply # 158183 19-Aug-2008 23:01
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Jarno: Apparently the feed from Beijing to TVNZ is 1080i. TVNZ will then downscale that to 720p for broadcast on TV1, SD for Sport Extra, and whatever resolutions they're going to use for the online streams.

Everything on TV1 is currently still in SD, including the news, so the difference in quality you saw is all down to better quality source material, rather than an HD broadcast.

---JvdL---


Correct me if i am wrong:

To my knowledge 720progressive has more detail than 1080interlaced? ie, 1080i would only show 540lines at any certain time, while 720p displaced 720lines at all times?


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  Reply # 158193 19-Aug-2008 23:42
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1080i that came from a film or 25/30 frames source will deinterlace to give more resolution but at the lower frame rate, but some TVs will make up frames (dejuddering) - to me that just looks crap but some people love it.

1080i from a video camera thats taking 50 or 60 frames a second and chucking half of each one away will never deinterlace properly and should have never being allowed to happen, and when deinterlaces will have 540, 1080, or somewhere in between lines of resolution depending on what modes were used on the various parts of the image, and how good the deinterlacer is. The answer when dealing with the tvs I have had a play with is "not very good at all" when given video sourced material, with all the issues seen on the old 100Hz tvs and watching 576 or 480i stuff on a flatscreen showing themselves, albeit at a smaller scale.

If you want to see a contrast between camera quality, look at goodmorning, the advertorial segments look to have being filmed on a vga webcam with vaseline on the lens and then with the top and bottom cropped and stretched to make it look widescreen.




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  Reply # 158205 20-Aug-2008 05:52
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skidzon:
Jarno: Apparently the feed from Beijing to TVNZ is 1080i. TVNZ will then downscale that to 720p for broadcast on TV1, SD for Sport Extra, and whatever resolutions they're going to use for the online streams.

Everything on TV1 is currently still in SD, including the news, so the difference in quality you saw is all down to better quality source material, rather than an HD broadcast.

---JvdL---


Correct me if i am wrong:

To my knowledge 720progressive has more detail than 1080interlaced? ie, 1080i would only show 540lines at any certain time, while 720p displaced 720lines at all times?

This is correct, but only if you're looking at a single frame. When you're looking at 1080i on TV, you're not being shown only a single frame - you're being shown the picture generated from a series of 1080i interlaced frames. The full resolution of 1920x1080 is there in the video you're seeing, but just not in every frame.

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  Reply # 158221 20-Aug-2008 08:49
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Sorry for being obtuse, but can someone confirm this is correct? (I have some doubts)

Given a Plasma/LCD hi Def TV is a Progressive display, then an interlaced signal (1080i eg TV3) must be handled by:

1) Taking 540 lines and upscaling it to the native resolution, or
2) interlacing two frames together thus halving the effective frame-rate

I think option 2 is the best, but it does mean you are going to get blurring on fast moving action.  I wonder why then, they chose 1080i as the native format for recording the Olympics?  I would ahve thought 720p would have been a better choice.

Well, it certainly would have mapped well to TV1 who are using 720p to broadcast..

ps. not that I'm complaining about the picture, which on my Panasonic Viera Plasma (1024*768) has exceeded expectations.





"There is no way to Peace -Peace is the Way" (A. J. Muste)

 


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  Reply # 158228 20-Aug-2008 09:06
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OK, doing some more reading up on this:

HDTV broadcast systems are defined threefold, by:

  • The scanning system: progressive scanning (p) or interlaced scanning (i). Progressive scanning simply draws a complete image frame (all the lines) per image refresh, whereas interlaced scanning draws a partial image field (every second line) during a first pass, then fills-in the remaining lines during a second pass, per image refresh. Interlaced scanning requires significantly lower signal/data bandwidth, but an interlaced signal loses half of the vertical resolution and suffers "combing" artifacts when showing a moving subject on a progressive display (although the worst effects can be mitigated by suitable image post-processing known as 'deinterlacing'). As some compensation, however, interlaced mode provides finer time-sampling, giving two (half-resolution) image samples in the same time interval as one (full-resolution) image sample in progressive mode.
Source: http://en.wikipedia.org/wiki/High-definition_television

They seem to be saying that 1080i recordings are shot at twice the frame rate to compensate for the fact that it is only a half-frame recording?!?

Furthermore, they also seem to be saying that a good progerssive TV's can potentially do a great job of dealing with the de-interlacing, so maybe 1080i was the best choice..




"There is no way to Peace -Peace is the Way" (A. J. Muste)

 


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  Reply # 158233 20-Aug-2008 09:12
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Quidam:

2) interlacing two frames together thus halving the effective frame-rate

I think option 2 is the best, but it does mean you are going to get blurring on fast moving action.  I wonder why then, they chose 1080i as the native format for recording the Olympics?  I would ahve thought 720p would have been a better choice.

It depends on the TV, but they generally try to deinterlace the current frame with the previous one, and recent TVs have some very smart techniques for doing this.

1080i video with minimal movement can produce very very sharp images, but when the movement starts the quality of the picture is definitely reduced - how much depends on lots of factors.

720p is much better for sports in this regard. It has a lower resolution, but doesnt suffer from these complications associated with movement.

Its not as clear cut as saying one is better than the other. It depends what is being broadcast, and what its being viewed on.

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