Iowa DTV Answers Blog
Bill Hayes has been Iowa Public Television's Engineering Director since 1999, and is responsible for Iowa Public Television's transition to digital television. In a little more than a year, analog television will be shut off, and we’ll all be watching television a little differently. Visit this page frequently to get answers to your digital television questions and to read about the industry and IPTV’s transition.
Thursday, January 3, 2013
"That is outrageously false! Unbelievable. I think we should call his manager and correct this."
We did contact the manager and this particular case is being corrected. However, if you hear similar claims, feel free to forward the names and affiliations of the people making the claims and I will be happy to straighten them out. I am always a little guarded regarding claims made by people trying to sell me their product...sadly many resort to distortions of the truth to make a sale.
Tuesday, November 20, 2012
Thursday, August 11, 2011
"We live in Dubuque and need every advantage when it comes to reception. Our system now uses a large outdoor antenna with a pre amp and a convert box. We receive all the national networks most of the time. We are thinking about buying a new television and assume that not all tvs receive digital signals the same. Is there any way to know which tv will do the best job?"
Boy is that a tough question. There are minimum performance specifications that all DTV receivers are expected to meet. Take for example the existing converter box you are using. In order to qualify for the coupon program the model theoretically had to pass tests. Early on in the conversion I started to see issues with a couple of the units we had so I purchased about 50 different makes and models and set up a little test facility in my basement. My goal was not to uncover whether some of the units actually didn't meet the required minimum performance specifications. Although I suspect a few of the units I tested didn't, I did not have the necessary laboratory test equipment necessary to make that call and since I was testing one of each unit, it was always possible that I was seeing issues with that particular unit and not the overall brand or model. What I wanted to do was to figure out which units worked best and which didn't perform as well. I was not in the position to make a recommendation of the best unit, but I felt pretty comfortable steering people away from units that didn't seem to work as well as others.
Unfortunately, I don't have the where with all to pick up 50 or so of the most popular DTV sets and do the same kind of testing. I have suggested to a number of organizations including Consumer Reports, that this type of testing should be done on a regular basis. Unfortunately over the air reception doesn't seem to be one of the key features that they consider important enough to invest in on any kind of regular basis. I am hoping that one of the broadcast organizations like the National Association of Broadcasters will consider underwriting the project. Until then, it is really more a matter of believing the specifications and the reputation of the manufacturer.
One test that I have suggested to a number of retailers is to put an attenuator into their master antenna feed. An attenuator would allow them to slowly make the signal reaching the television sets weaker which replicates distance from the transmitting antenna or increased moisture in the air or signal blockage from foliage, all of which degrade reception. By doing this on their master antenna they could observe all of the televisions connected to the antenna at the same time and see which ones begin to have problems first. This would be an indicator of which receivers are performing better as the signal fades. It is not the most scientifically accurate way of doing it but it does provide some general guidance. I have found smaller, locally owned television shops much more willing to do something like this while the bigger stores will not.
I hope this helps a little and if I ever find a source of independent test evaluations, I'll let you know.
Tuesday, January 26, 2010
Younger people are virtually oblivious to the fact that there is free wireless television. All their lives, the television has been connected to a wall plate that was connected to the cable head end so they have no experience. Middle aged people remember when they had an antenna on their roof hooked to their television but probably went to cable to get some add on services that were available via cable and the side benefit was that the cable also carried the local broadcast stations and they didn't have to worry about an antenna anymore and they have kind of forgotten about the free wireless nature of broadcast television.
If you're a basic cable subscriber, I would recommend that you keep a log for a month or so of your television viewing and determine how much time you actually spend watching local broadcast channels versus cable only channels. But don't just track the time, also grade the content you watched to determine if the viewing was a good use of your time. If you find that the majority of your good viewing time was spent watching broadcast television, then you may want to consider dropping your paid service in favor of the free over the air service. You may actually find that you get more out of the free service than you get from the basic paid service.
As an example, in the Des Moines area where I live, we have PBS, ABC, CBS, NBC, MNT, CW, ION and FOX network affiliates. The majority of these stations are broadcasting multiple services so there are probably 14 or 15 free channels to choose from. The primary channels probably carry the content that you watch the majority of the time and the ancillary channels carry additional services that may be of interest. My own station carries a full time HD feed of PBS and two ancillary services, one called Kid/Create which offers kids programming and how-to programs and the other IPTV/World is news and information programming. All of it available for free and from my experience, the HD content delivered is typically better than what is delivered via the subscription based services.
If you're happy with your subscription based services, that is great. But if you're looking for a way to trim expenses, dropping the pay service could save some money and may not be as big a sacrifice as you think.
Monday, December 28, 2009
One of the questions that I get most frequently is what's wrong with the picture. It seldom relates to the quality of the picture but the content of the picture. Why are the titles cut off? Why a titles in the middle of the screen rather than at the edge of the picture like they used to be? The issue is aspect ratio which is the relationship between the height and width of the picture. This is an important concept to grasp because in the transition from analog television to digital television, the aspect ratio changed. Traditional analog television has an aspect ratio of 4x3 which means that the picture is 33% wider than it is tall. Digital television's have an aspect ratio of 16x9 which means that the picture is about 78% wider than it is tall. This represents a pretty significant difference in aspect ratio. In my office I have an analog television with a screen that is 16 inches wide and 12 inches all. If you do a little basic math that confirms that the screen is 33% wider than it is tall. I also have a digital television in my office with a screen that is about 22.5 inches wide and about 12.7 inches tall. The same basic math will show that the screen is about 78% wider than it is tall.
If the desire is to show the complete 16x9 image in the existing 4x3 television frame, there are only two options. The first is to do what is called letterboxing the image. What this means isthat we scale or adjust the width of the 16x9 picture to fill the width of the 4x3 frame. The side effect of this scaling is that there is a portion of the 4x3 frame that the picture does not fill. In essence a black matte is generated to fill from the top and bottom edges of the picture to the top and bottom edges of the frame. As you can see from the example the entire 16x9 picture is displayed with the proper width to height relationship and is made to fit within the 4x3 frame. Image integrity is maintained but the actual image on the screen is smaller than a 4x3 picture would be.
The other option for displaying a 16x9 image on a 4x3 display is to forget about maintaining image integrity. in this case we would scale the width of the image to fill the width of the 4x3 frame and then independently scale the height of the image to fill the 4x3 frame. As you can see from the example, the 16x9 image fills the 4x3 screen but the picture is distorted. The characters are vertically stretched so that they appear taller and skinnier than normal. Conversely, if you look at the horizontal table, it appears to be shorter and than normal. So the 4x3 screen is filled but the picture content is compromised.
As I said, there are really only two ways to display the entire 16x9 image on a 4x3 screen. There are however other options that can be used. One popular one is called cropping or center cutting. If you have every taken a picture that is too large for a frame and trimmed it to fit, you have cropped. In television, because most of the important visual information is in the center of the screen, a 4x3 image is cut from the center of the 16x9 picture. Once again, the 4x3 screen is filled but the image is compromised. In the example image, although the characters in the original image maintain their proper width to height relationship, three of the original characters are no longer displayed so in this case we would see Jesus and the nine apostles. I am certain that Leonardo Da Vinci would not believe that this was an accurate interpretation of his work or an accurate representation of the historical event he is recording.
One technique that is often suggested is what is called center or 4x3 protect. What this means is that when the picture is being created, the action should be framed to all take place within the 4x3 center of the 16x9 frame. In some cases this is being done with some success but it is not always possible. In the example picture, this is what the Last Supper might have looked like if Da Vinci had created on a 16x9 canvas for display in both a 16x9 and 4x3 frames. As you can, all of the characters are in the image and their width to height ratio is proper but the image is unbalanced because of the compression of all of the action to the center of the frame while the left and right edges are more vacant and unused. In this case the image would look unusual on both displays.
It is challenging and sometimes impossible to create content that makes full use of the wider digital aspect ratio while trying to insure the content's integrity on legacy displays. Realizing that 4x3 displays are the legacy device and will eventually be gone and 16x9 or wider displays will be the norm, content needs to be created to take advantage of the benefits of new display technologies. For display on legacy devices, the first choice should be to maintain the integrity of the wide screen images through letterboxing.
Monday, June 15, 2009
If you know of someone who is still having trouble receiving Iowa Public Television, or someone who needs help, tell them to call IPTV at 1-800-532-1290. We'd be happy to help them.
Meanwhile, enjoy IPTV, IPTV LEARNS, and IPTV WORLD. Thanks!
Monday, February 9, 2009
Iowa Public Television is, at our core, a public service media organization. We believe it's important to serve all Iowans, regardless of where they live or what they can afford to pay. And in the past year, we've fulfilled some of that public service role by assisting Iowans with questions and problems converting to digital television. We've conducted more than 100 town hall meetings around the state, aired 30 hours of information about the switch, and talked with thousands of Iowans having difficulty making the transition.
Though we did not advocate for the delay, we do see it as our role to take advantage of the extra time to provide information and assistance to those Iowans who aren't yet ready.
We have no doubt Iowans are aware of the switch - and we're not staying analog to help procrastinators. We believe, through our conversations and visits with Iowans, that most of those who haven't made the switch are having unanticipated difficulties with reception and antenna issues. Still others applied for converter box coupons and are now on a waiting list, or never received coupons to begin with.
There will be utility costs associated with staying analog for a few more months, and in these budget times taking on those costs was a difficult decision. We're finding other ways to save in these demanding budget times, because we strongly feel these costs are an investment in helping as many Iowans as possible be prepared for the switch. And of course, the individual contributions made by members will continue to go directly toward programming.
Iowans rely on television, not just for entertainment and a connection to the outside world, but for important public safety information. And Iowa's families - particularly those families in lower income situations without access to pay television or new televisions - rely on our service for safe, educational children's programs.
So though staying analog does incorporate additional expense, we feel the cost allows us to do the important public service mission with which we are charged - helping all Iowans through public media. It's why we were created, why we are supported, and it's our unique responsibility.
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