seeking help with hdtv

[Wizard Mentor]

I just bought a phillips hdtv (1920x1280, 29000:1 dynamic range) and am having severe pixelation problems from antenna fed analog stations.

The digital stations are fine (though I get pixelation when people move to fast).

dvds play great from my new upconverting dvd player.

The tv stations were much cleaner on my sdtv with the same antenna.

Is the analog signal the problem? Do I need a need a new digital antenna? Any advice?

Thanks in advance.

 

[DaRizzle]

Ive heard of this too where standard def pics will be worse on hdtvs. I have an LCD and dont have that big of problem. Could you possibly just have the picture in the wrong format? For example if u had it set to "wide" it would stretch it all out of proportion. Some people are anxious to have the entire screen show part of the picture but that screws everything up...

...another thought...maybe check your cable box and check all the output boxes (1080, 720, 480, etc)...dont just have the 720 or just the 1080 box checked....I learned that from a dude smarter than me on this stuff

 

[Denny Crane]

They recently switched from analog to digital TV standard. You may have seen commercials on TV about how you need to get a box to get over the air signals.

Even before DTV, SDTV was digital. Makes no sense? At some point along the way from origin to your antenna, it was digitized (mpeg) sent over a fiber optic cable or satellite, then reconverted to analog and sent over the air. Additionally, the local stations can store those those reruns of Boston Legal in digital format (saves space, can be stored on hard disk or CD or DVD), converted to analog and broadcast after the late night news.

The thing about compression is that it's "lossy." This means that when you compress a picture and then decompress it, the picture is not exactly the same as the original. It's plenty good enough to fool the human eye though. If you compress a picture that's already been compressed and decompressed, the quality gets worse.

The idea of compression is to make the resulting stream (movie, show, whatever) smaller in digital format. Uncompressed movies on blu ray take up 50G on those disks. The same movie on DVD takes up 5G. That's why the picture on blu ray is so much better (no loss at all).

Compression works best if the background in the stream is mostly static. That is, the stream will compress really small. The compression algorithms basically look at the change in the picture on the screen from 1/60th of a second to the next - the less change, the more compression. So for sports, you have the camera panning across the crowd in the stands and the picture is almost completely different from 1/60th to the next. The compression is worse. They can force it to compress to a specific size, but it causes those artifacts you see.

Technically, the delta from frame to frame is done in 8x8 pixel blocks. Those 8x8 are what you see a lot when a digital picture is garbled.

 

[Denny Crane]

Oh yeah, those nice new HDTVs with awesome picture really show off the faults in bad video sources.

 

[bodyman5001]

Oh yeah, those nice new HDTVs with awesome picture really show off the faults in bad video sources.

They sure do, but then again during American Idol you can see the exact outline of Randy Jackson's armpit sweat and watch it expand!!!!! Awesome.

I just watched an OLD Star Trek episode the other night that my tv said was 1080i and it looked awesome. At least as good as it ever could look I think.

 

[Wizard Mentor]

They recently switched from analog to digital TV standard. You may have seen commercials on TV about how you need to get a box to get over the air signals.

Even before DTV, SDTV was digital. Makes no sense? At some point along the way from origin to your antenna, it was digitized (mpeg) sent over a fiber optic cable or satellite, then reconverted to analog and sent over the air. Additionally, the local stations can store those those reruns of Boston Legal in digital format (saves space, can be stored on hard disk or CD or DVD), converted to analog and broadcast after the late night news.

The thing about compression is that it's "lossy." This means that when you compress a picture and then decompress it, the picture is not exactly the same as the original. It's plenty good enough to fool the human eye though. If you compress a picture that's already been compressed and decompressed, the quality gets worse.

The idea of compression is to make the resulting stream (movie, show, whatever) smaller in digital format. Uncompressed movies on blu ray take up 50G on those disks. The same movie on DVD takes up 5G. That's why the picture on blu ray is so much better (no loss at all).

Compression works best if the background in the stream is mostly static. That is, the stream will compress really small. The compression algorithms basically look at the change in the picture on the screen from 1/60th of a second to the next - the less change, the more compression. So for sports, you have the camera panning across the crowd in the stands and the picture is almost completely different from 1/60th to the next. The compression is worse. They can force it to compress to a specific size, but it causes those artifacts you see.

Technically, the delta from frame to frame is done in 8x8 pixel blocks. Those 8x8 are what you see a lot when a digital picture is garbled.

So, my local repeater in La Grande is actually converting the digital signal back to analog to send over the airways? Sigh. Is it because that they'd have to buy new equipment to send in digital?

As far as compression and decompression is concerned, it seems like the TV could have a very simple Low Pass Filter option to average out the pixelation.

Regardless, I still don't know what to do about it. I tried sending the signal to an old vcr before going to the TV, but it didn't help. I did change the aspect ratio, and it helped a tiny bit.

 

[Denny Crane]

So, my local repeater in La Grande is actually converting the digital signal back to analog to send over the airways? Sigh. Is it because that they'd have to buy new equipment to send in digital?

As far as compression and decompression is concerned, it seems like the TV could have a very simple Low Pass Filter option to average out the pixelation.

Regardless, I still don't know what to do about it. I tried sending the signal to an old vcr before going to the TV, but it didn't help. I did change the aspect ratio, and it helped a tiny bit.

There isn't much you can do if the video source isn't great. The TV is so good it really shows you how crappy the signal is.

If it was recorded SD on analog equipment, it's being digitized at a loss. If it's a new program recorded with HD cameras, etc., it's about as good as it can get.

They stopped broadcasting in analog a while ago. Are you sure you're getting analog stations? If you don't have a digital antenna, and you're not using something like DirecTV or cable for your programming, then a digital antenna (the cheapest one you can find) will allow you to get any digital SDTV and HDTV signals being broadcast near you.

 

[Denny Crane]

They sure do, but then again during American Idol you can see the exact outline of Randy Jackson's armpit sweat and watch it expand!!!!! Awesome.

I just watched an OLD Star Trek episode the other night that my tv said was 1080i and it looked awesome. At least as good as it ever could look I think.

I read some time ago that they digitally remastered those old shows and improved the special effects.

I haven't seen any of them that I could tell were remastered though. They still look SD to me.

 

[bodyman5001]

I read some time ago that they digitally remastered those old shows and improved the special effects.

I haven't seen any of them that I could tell were remastered though. They still look SD to me.

That makes sense, they didn't look HD but they looked more like a computer animated cartoon. Still quite nice and not fuzzy though, had to stretch the format for the widescreen which changed their shapes a bit.

 

[Wizard Mentor]

For the curious, I found some answers:
My area is part of the Blue Mountain Translator District which has "low power" transmitters, and therefore are not required to switchover. In fact, they have not and so are still transmitting analog signals. There is no word on when they will switch to digital, but it is said to require "grant money."

So, I'm stuck in snowville for an indeterminate amount of time - hope the wife's patience lasts that long!

As an interesting aside, several local subscribers have purchased converter boxes which are, at best, useless. Some converter boxes have analog pass-through, but some don't. So, they can't even connect their boxes up without snow!

 

[Denny Crane]

For the curious, I found some answers:
My area is part of the Blue Mountain Translator District which has "low power" transmitters, and therefore are not required to switchover. In fact, they have not and so are still transmitting analog signals. There is no word on when they will switch to digital, but it is said to require "grant money."

So, I'm stuck in snowville for an indeterminate amount of time - hope the wife's patience lasts that long!

As an interesting aside, several local subscribers have purchased converter boxes which are, at best, useless. Some converter boxes have analog pass-through, but some don't. So, they can't even connect their boxes up without snow!

If you have line of site to the satellite, DirecTV has 50 channels for $29/mo and 150 channels for $35/mo for 12 months, then $55 thereafter. You can get NBALP on it, too.