One of my locals picture size has shrunk, Why?

[DefDude]

I get a local channel 55 out of mobile/pensacola. last night I noticed that the size of the pic has shrunk down and will no longer fill the screen on any tv, HD or SD.... with any of my receivers 722,522,322. Even when I stretch or any of the zoom's, It looks like a box in a box in any format. this is one the channels I don't get OTA so my question is, does this have to do with the switch to digital, or Dish. the pic quality does look somewhat darker and clearer but I'm sure if it is because of the smaller pic or because it is now a digital signal.

 

[KAB]

My guess is the station is going through some testing. Dish merely passes along what the local sends.

 

[Pepper]

I have this channel OTA and I have never, ever, ever seen anything HD. Perhaps that is about to change. Or perhaps they are just now transmitting their usual SD content in a 16x9 HD format, and dish is passing that along. I will have to check that tonight.

They could be continuing to test, as they only brought a digital channel online back in February when they discontinued the analog.

 

[digiblur]

Don't you love it when a SD channel passes stuff in letterbox 4:3? On your HDTV you get the blackbars on the bottom/top and then the sides.

 

[DefDude]

On my sony 36 inch 4x3, I get this channel in a 29 inch 4x3 size, it's a real clear pic as long as you move close enough to see. I guess A lot of us will have some issues on june 12th, may as well start a sticky for them Scott.

 

[Awohar]

Don't you love it when a SD channel passes stuff in letterbox 4:3? On your HDTV you get the blackbars on the bottom/top and then the sides.

to determine if this is the case, one can usually play with the contrast/picture settings and get two different shades of black for the side bars and the letterbox top and bottom bars.

 

[Barry Erick]

Sounds like the SD feed is not set in Center Cut. That makes a SD or HD picture fit a 4:3 and the user can stretch it to fill a 16:9. Center cut does not distort the picture, but leaves it up to the user.

If Dish is picking this up over the air, it is most likely DISH that is doing this wrong. If other stations are ok, then the station is originating wrong. Very easy to do if you are not familiar with the up converter equipment at the station. SD should be sent at normal size and black bars on the sides to allow the user to do what they want with it. That is how every major network does it and how every station should. No stretching.. Let the user do that if they want.

 

[noremac]

I believe that when Dish retransmits an SD version of a digital OTA channel which is being broadcast in widescreen 16:9, they ask the station to select how they prefer the SD version to be formatted. Many/most stations are broadcasting a mix of 4:3 and 16:9 original content, but choose to keep their native format in HD, which means that 4:3 content will have black bars. There is no clean solution to this, except to wait for everybody to get a widescreen TV.

 

[Pepper]

When I checked the OTA channel this weekend, it was indeed a 4x3 letterboxed with sidebars. Dish is transmitting exactly what they are getting from the station.

 

[highdefjeff]

Picture quality and signal relationship. TRUTH is here!

I get a local channel 55 out of mobile/pensacola. last night I noticed that the size of the pic has shrunk down and will no longer fill the screen on any tv, HD or SD.... with any of my receivers 722,522,322. Even when I stretch or any of the zoom's, It looks like a box in a box in any format. this is one the channels I don't get OTA so my question is, does this have to do with the switch to digital, or Dish. the pic quality does look somewhat darker and clearer but I'm sure if it is because of the smaller pic or because it is now a digital signal.

It has to do with low signal strength or poor signal quality.

The shrunken picture is a type of scalability that is built into the MPEG forward error correction. Your television receivers AND your Dish receivers (Directv, digital cable) everything using MPEG 2/4 has scalability, built right in.

When you have less than the minimum of 70 on a standard digital signal quality meter (everyone's meter except the new improved dish signal meter where there is no longer any standard...), there is built-in or rather "written" in, coding that allows for the decoding of a weaker, or compromised signal. It is called Scalable Video Coding extension, and has been a part of HDTV since at least 2005.

One of the types of scalability that is available to use, is spatial scalability. This scalability says, "Since the signal is poor and there is not enough data to produce the full size picture at the proper resolution, then I'll display the proper quality, or resolution, at a reduced size."

These are three types of scalability. They are temporal, spatial, and fidelity scaling options. Broadcasters and TV manufacturers use all three of these handy, low-signal digital tricks.

Spatial scalability is what you are witnessing on your TV. Here the quality remains but the size of the picture decreases. Dish does NOT use this type of scaling because it too easily leads to the truth of the picture/signal relationship.

Fidelity scalability is scaling that reduces the quality of the picture (grainy, blurry) but maintains size. Since most people don't see this difference, and the perpetuation of the "all-or-nothing LIE" says that signal is NEVER the problem, this type of scaling is acceptable to Dish.

Temporal scalability refers to time scalability and accounts for a good portion of the audio sync problems that are being reported. Since these also have a reputation of being blamed on software issues and such, so this scaling is also acceptable.

The rest of the story is on WOWVision and the HDTV Picture Quality blog.
The link to the technical info regarding SVC scaling follows:

http://ip.hhi.de/imagecom_G1/assets/pdfs/Overview_SVC_IEEE07.pdf

 

[sam_gordon]

It has to do with low signal strength or poor signal quality.

What in the h-ll are you talking about? Are you for real with all this stuff? What's your background?

To the OP... someone (either the local broadcaster or Dish) are incorrectly downconverting the signal. An HD signal, by definition is 16x9 (widescreen). When you downconvert HD to SD, you need to program the downconverter on what to do with the signal. There are three practical options...
Letterbox: This will show the entire 16x9 image on a 4x3 screen by adding black bars at the top and bottom of the screen. The good thing is even someone watching on a 4x3 screen sees EVERYTHING that the content producer wants you to see.
Center Cut: This will leave the middle part of the image while "chopping off" the sides of the 16x9 picture.
Anamorphic: This will "squeeze" the entire 16x9 image into a 4x3 image. People will look extra tall and skinny. It basically distorts the image to anyone watching on a 4x3 set. If you're watching on a 16x9 set, you can have the set "expand" the picture back out. Not many stations would do this to send content to their viewers.

Now, as far as what you're seeing... somewhere a downconverter is set to letterbox. The problem with this is when you letterbox a 4x3 program (many commercials, all soap operas, some other shows), you end up putting black bars on all four sides. If you watch a 4x3 program on a 16x9 set, you should have black bars on the left and right. But keep in mind, the "letterbox" setting on the downconverter shows EVERYTHING from the original 16x9 image... in this case, including the black bars on the left & right. So now you see black bars on all four sides... also known as "postage stamp".

I hope this helps.

BTW, MY background? I'm an engineer at a local broadcast station.

 

[digiblur]

What in the h-ll are you talking about? Are you for real with all this stuff? What's your background?

Ignore hideafjeff, he's constantly spitting out his propaganda that you don't have a good HD picture unless you have maxed out your dish. But this by far my favorite! It just so happened to drop signal on the side bars of the screen causing them to go black. LOL!!! AMAZING!! Maybe it's because the guy has a square LNB and not a rectangular 16:9 LNB right?

 

[Pepper]

The letterbox setting would be ideal, if the station in question ever aired anything in 16x9 HD, which to my knowledge it never has.

 

[sam_gordon]

The letterbox setting would be ideal, if the station in question ever aired anything in 16x9 HD, which to my knowledge it never has.

Then my guess on what's happening is Dish is now using the station's DTV feed (since analog will be cutoff shortly). The DTV feed IS 16x9 (even if the content is 4x3). It's possible Dish has their downconverters set to letterbox. That would explain the "postage stamp". Of course, if someone watches the station OTA, they would see it fine (non-postage stamp). If that's the case, the problem seems to be with Dish.

 

[Awohar]

Ignore hideafjeff, he's constantly spitting out his propaganda that you don't have a good HD picture unless you have maxed out your dish. But this by far my favorite! It just so happened to drop signal on the side bars of the screen causing them to go black. LOL!!! AMAZING!! Maybe it's because the guy has a square LNB and not a rectangular 16:9 LNB right?

Exactly...and more than likely if the OP was to mess with his contrast settings he would see two different shades of black for the top&bottom versus the black for the side bars. Absence of data at best would result in a consistent black slate of just a "null" shade of black versus having two different shades.

 

[BuddyBoy]

Ignore hideafjeff, he's constantly spitting out his propaganda that you don't have a good HD picture unless you have maxed out your dish. But this by far my favorite! It just so happened to drop signal on the side bars of the screen causing them to go black. LOL!!! AMAZING!! Maybe it's because the guy has a square LNB and not a rectangular 16:9 LNB right?

Or maybe you need one of them wide dishes to get widescreen content. That's it - Dish 500 for 4:3 SD, and the wider Dish 1000 for 16:9 HD. I mean, they say you need a Dish 1000 for HD, right?

No one could be that stupid. He has to be a troll.

 

[hendrix04]

What in the h-ll are you talking about? Are you for real with all this stuff? What's your background?

To the OP... someone (either the local broadcaster or Dish) are incorrectly downconverting the signal. An HD signal, by definition is 16x9 (widescreen). When you downconvert HD to SD, you need to program the downconverter on what to do with the signal. There are three practical options...
Letterbox: This will show the entire 16x9 image on a 4x3 screen by adding black bars at the top and bottom of the screen. The good thing is even someone watching on a 4x3 screen sees EVERYTHING that the content producer wants you to see.
Center Cut: This will leave the middle part of the image while "chopping off" the sides of the 16x9 picture.
Anamorphic: This will "squeeze" the entire 16x9 image into a 4x3 image. People will look extra tall and skinny. It basically distorts the image to anyone watching on a 4x3 set. If you're watching on a 16x9 set, you can have the set "expand" the picture back out. Not many stations would do this to send content to their viewers.

Now, as far as what you're seeing... somewhere a downconverter is set to letterbox. The problem with this is when you letterbox a 4x3 program (many commercials, all soap operas, some other shows), you end up putting black bars on all four sides. If you watch a 4x3 program on a 16x9 set, you should have black bars on the left and right. But keep in mind, the "letterbox" setting on the downconverter shows EVERYTHING from the original 16x9 image... in this case, including the black bars on the left & right. So now you see black bars on all four sides... also known as "postage stamp".

I hope this helps.

BTW, MY background? I'm an engineer at a local broadcast station.

This must be why when my OTA signal goes below 65% i loose picture completely and when i am about 65% i have a perfect picture...

 

[sam_gordon]

This must be why when my OTA signal goes below 65% i loose picture completely and when i am about 65% i have a perfect picture...

I never said as much. I was explaining the "shrunk" picture. And you just invalidated hideafjeff's theory. According to him, if you get a good picture with a 65% signal strength, your picture will be BETTER with a 70-75% signal strength. According to what YOU wrote, you either get "all or nothing". But according to hideafjeff, that's a "lie".

If you look at a digital OTA signal on a scope, it looks almost like a square wave __| |__ (I don't have a good way to draw a line between the two vertical sections at the top). As long as you're looking at the "top" (peak) of the signal, you get a good picture. However, as you start to come down off the top, the signal will start to breakup. Because the difference between "full signal" and "no signal" is so drastic, it's basically "all or nothing".

Now, if you see blurring or poor resolution in a picture, that's due to compression. The compression can be in the delivery from the content producers to the local stations, AT the local stations, in the local stations transmission path, between the cable/satellite reception point and THEIR transmission system, or in the cable/satellite transmission system.

I also find it interesting that hideafjeff has a link on his website talking about Monster cables being a ripoff. On the link HE points to (one on CNET), it's pointed out that HDMI signals are digital and that they either "work or they don't" (sounds a lot like "all or nothing"). So he apparently believes the "all or nothing" when it comes to digital signals through an HDMI cable, but not through satellite, cable or OTA.

ETA: The H.264/AVC article hideafjeff keeps pointing to is an article on COMPRESSION. H.264/AVC is a COMPRESSION standard (like MPEG, JPG, etc). It's not a TRANSMISSION (like 8VSB, DVB, DVB-S2, etc) standard. So of course the article is going to talk about picture quality loss because that's what you get when you use compression.

 

[KAB]

Ignore hideafjeff, he's constantly spitting out his propaganda that you don't have a good HD picture unless you have maxed out your dish. But this by far my favorite! It just so happened to drop signal on the side bars of the screen causing them to go black. LOL!!! AMAZING!! Maybe it's because the guy has a square LNB and not a rectangular 16:9 LNB right?

Agreed. He really outdid himself with this one

 

[Jim5506]

So...

If I want my picture to shrink to 4X3 letterboxed with black bars all around, I need to mis-align my dish so the signal is marginal?