Networks flip flopping DTV signal

[Trailryder]

Hey all,
I don't know if this happens all over the country or with just my area network affiliates.

I get my DTV and HDTV over-the-air(broadcast). You know, the big 3, CBS, NBC and ABC. I've noticed, especially during prime time, but during the day too, the signal switches back and forth between what seems to be the digital and analog signals. The program being broadcast in digital, and then when the commercials come on it's like someone flips a switch to analog. Then when the program comes back on it may be like someone down at the network isn't paying attention and the program will be in analog for a bit, then suddenly switch back to digital or even HD, depending on the program.

What's up with that?

And who is doing it? The local affiliate or the network themselves?

It's like they're trying to save a little bandwidth or something during commercials.

The switch is very obvious, as the colors and audio is much better with digital. There's also a perceptible 1/2-1 second time difference between signals, so you may get a "deja vu" kind of thing when it switches.

Can anyone shed some light on why they're doing this?

I hope after Feb.'09 this kind of thing stops. If not, I'll be complaining to the FCC.

I'd thought about getting cable TV. They offer the major networks in both analog and digital, digital at a higher cost. But if the cable company gets their feed from the networks and they're the ones flip flopping on the signal all the time it does me no good to get cable for those digital channels.

Anyone else dealing with this phenomenon?

Thanks

[gadgetguy]

Can't say I've seen that. I've seen HD show to SD commercials and what seems to be a slow switch back when the show returns, but not digital/analog switch. But then again, if they switched to analog I would receive "no signal" as I'm using converter boxes so there's no NTSC tuner to receive the analog. That's definitely not happening.

[vhelp]

Haahh. Then I wasn't going crazy or seeing things. They (whoever they are) were doing the same thing during the 2008 Summer Olympics. I knew I wasn't crazy. And I remember they did it during the closing ceremony, too.

And this is prob why my Pinnacle recording software kept bombing out because it coudln't figure out what was going on.

-vhelp 4929

[edDV]

What is your local market?

Does this happen a on all stations in the same way?

What DTV are you using?

A typical local station gets their MPeg2 digital network feed at higher than broadcast bitrate then transcodes and multiplexes it to ATSC for broadcast. The network feed has time segments where local stations insert their own commercials and news clips.

Smaller stations lack the capability for digital origination so will use an upscaler-digitizer to convert 4:3 local analog to digital. During non-prime time they feed the upscaler-digitizer their normal analog programming.

If the network program is high definition 16:9 digital with AC3 audio, the commercial inserts will be upscaled local 4:3 analog with simple stereo audio. It is possible under ATSC rules to force the TV to change audio/video standards on the fly (e.g. from 1080i to 480i) but most stations maintain the 16:9 HD-AC3 feed to the transmitter and do all the format switching at the TV station. When our local market started digital broadcasting, it was almost a joke to watch them screw up the local breaks. Often they would fail to switch out of 4:3 sidebar mode when the break was finished causing the 16:9 network feed to show letterboxed into the 4:3 window. Even today, they often screw up switching from stereo to AC-3 5.1 audio.

Changing to cable will probably have no effect. They just take the TV feed and remodulate to QAM. In some markets, cable will do their own commercial inserts (usually with loud audio). They do this only under agreement with the local broadcaster.

[Trailryder]

Sorry, I'm probably using the term DTV wrong. I mean digital broadcast TV signals.

My local market is Amarillo, Tx.

edDV, what you describe is Greek to me but I don't doubt that is what's happening.

I hope after Feb.'09 this changing standards on the fly becomes illegal.

Thanks for the explanation.

[guns1inger]

If you are using a digital settop box or digital TV then you cannot be getting a cut-over to an analogue signal. As pointed out earlier, if the digital stream stops or is replaced by an analogue stream you would simply lose your image completely. What edDV is saying is that in some markets, regional affiliates will cut in their own adverting that is still digital, but effectively is just upscaled analogue converted to digital on the flay as necessary. The quality of this will be far lower than the surrounding HD material, so it may well appear to be analogue, but it is definitely part of the digital stream, only from a low quality source.

[edDV]

Sorry, I'm probably using the term DTV wrong. I mean digital broadcast TV signals.

My local market is Amarillo, Tx.

edDV, what you describe is Greek to me but I don't doubt that is what's happening.

I hope after Feb.'09 this changing standards on the fly becomes illegal.

Thanks for the explanation.

As I explained,they probably aren't switching standards on the fly although it is legal. They are switching from network to local generated signals at the TV station.

ATSC allows 18 different formats for resolution, in interlace or progressive. Most network stations broadcast their primary channel all day long as 1920x1080i or 1280x720p. PBS sometimes switches formats for evening vs. daytime. Other stations like ION broadcast 4 704x480i subchannels all day.
http://www.hdtvprimer.com/ISSUES/what_is_ATSC.html

If they were switching formats, your TV would probably indicate 1080i/720p/480i during the switch.

Here is a forum where you can discuss your Amarillo, TX over the air experiences with other locals.
http://www.avsforum.com/avs-vb/showthread.php?p=14933361#post14933361

The only differences after Feb 9, 2009 are some digital stations change channel number and many increase power. That and the analog transmitters are turned off for good. The digital standards don't change.

Look for market 131 on this chart for the transition plans.
http://www.rabbitears.info/dtr.php

[redwudz]

Where I lived before, the OTA feeds would change back and forth from high definition to standard definition all the time. Several major football games and other sporting events were in SD. The local public broadcasting station was the only one that was all HD. But unless you wanted to watch Sesame Street in HD, not much available there.

The local cable where I am now is all SD. Only OTA has HD.

[Trailryder]

My TV is a 46" Toshiba LCD. Pick up my signals with an antenna in the attic.

Why would they suddenly switch to an upscaled analog converted to digital signal from one that's already digital?

Example:
During a commercial (which you say is most likely inserted locally)it will look like a nice, vivid colors, stereo sound like what I assume a digital source would be like, and then in the middle of the commercial it will switch to "something" of much lower quality.

From what you guys have said so far I'm guessing that the programming/commercials inserted locally are not all manufactured originally to the same aspect ratio, resolution, or quality, either analog or digital. So in an effort to make a 2 minute commercial break look somewhat uniform they will do this upscaling you speak of. ??????

Then when the commercial break is over and prime time programming resumes, which is digital or even HD, if someone forgets to switch off the "upscaling on the fly", the program will look analog, in both resolution, aspect ratio and audio. ????????? An example would be, I was watching Eli Stone the other night. When resuming after a commercial break, video and audio was that of what you'd see on the regular analog channel, then BAM, Like flipping a switch, the digital, HD video and audio are back.

You speak of the quality of stuff being lower than the surrounding HD material. An example of that would be like when an AT&T, Verizon Wireless or one of the other HD commercials come on. They're interspersed with other commercials of lower quality, so does that mean there's someone sitting at a console somewhere ready to hit the switch for "upscaling on the fly" before and after those HD commercials?

Like someone said, I hope it's just a "transition" thing and after Feb.'09 they won't need to be doing all this upscaling on the fly.

Thanks for the explanations and links.

What edDV is saying is that in some markets, regional affiliates will cut in their own adverting that is still digital, but effectively is just upscaled analogue converted to digital on the flay as necessary. The quality of this will be far lower than the surrounding HD material, so it may well appear to be analogue, but it is definitely part of the digital stream, only from a low quality source.

[edDV]

Blame this poor guy in a small market TV master control room. He has an SD and an HD network feed coming in and and has to feed two transmitters (analog and digital). A single commercial break might have a dozen clips to play. Some come from the network feed, others come from tape machines (still Betacam analog in small markets) that must be cued and pre rolled 5 seconds to switch to air. There are also slides with pre-recorded voiceovers and even cuts to a live news studio. In a small station all this is done with automated sequencers or manually to a computer cue sheet.

Small station semi automated Master Control


A small station will be doing all this in analog to the analog transmitter and upscaling the same analog signal to the digital transmitter. This is why you see a quality difference. Larger stations will have the breaks preloaded into servers with computer schedule control. Many of source tapes are still analog Betacam but newer servers can download commercials from a sat feed and these can be high def. Very few local ads are produced in high def digital so most are upscaled from 704x480 to 1920x1080 or 1280x720.

A modern automated Master Control Suite. The equipment and servers may easily cost a half million+.


You can call your local station and ask to observe master control from a seat in the rear. Sort of like a ride along with a cop. You won't understand the operational complexity until you see it first hand.

So will your locals get the fancy automated equipment? My guess is Amarillo (market 131) gets the ten-fifteen year old stuff as hand me downs from the larger market brother stations. The operators probably get half the pay of the big stations for four times the work as well.

[edDV]

Imagine the Master Control nightmare for your local CBS KFDA-DT that also simultaneously operate three other networks on the same digital channel. This is in addition to running the analog transmitter feeds.



The CBS HD must be fairly low bit rate since they carry three other SD stations on the same digital channel.

[edDV]

My TV is a 46" Toshiba LCD. Pick up my signals with an antenna in the attic.

Why would they suddenly switch to an upscaled analog converted to digital signal from one that's already digital?

Because they make their money only from locally inserted commercials. They convert their local analog signal to digital.

Example:
During a commercial (which you say is most likely inserted locally)it will look like a nice, vivid colors, stereo sound like what I assume a digital source would be like, and then in the middle of the commercial it will switch to "something" of much lower quality.

From what you guys have said so far I'm guessing that the programming/commercials inserted locally are not all manufactured originally to the same aspect ratio, resolution, or quality, either analog or digital. So in an effort to make a 2 minute commercial break look somewhat uniform they will do this upscaling you speak of. ??????

The nice looking 16:9 and 4:3 commercials come from the network. The lower quality upscaled inserts are done locally so they can pay their staff and stockholders.

Then when the commercial break is over and prime time programming resumes, which is digital or even HD, if someone forgets to switch off the "upscaling on the fly", the program will look analog, in both resolution, aspect ratio and audio. ????????? An example would be, I was watching Eli Stone the other night. When resuming after a commercial break, video and audio was that of what you'd see on the regular analog channel, then BAM, Like flipping a switch, the digital, HD video and audio are back.

Yep, the guy forgot to flip a switch.

You speak of the quality of stuff being lower than the surrounding HD material. An example of that would be like when an AT&T, Verizon Wireless or one of the other HD commercials come on. They're interspersed with other commercials of lower quality, so does that mean there's someone sitting at a console somewhere ready to hit the switch for "upscaling on the fly" before and after those HD commercials?

No he is pushing buttons to cut from net feed to upscaled local inserts.

Like someone said, I hope it's just a "transition" thing and after Feb.'09 they won't need to be doing all this upscaling on the fly.

The only thing that changes Feb 2009 is the analog transmitter will be shut down. That means they have more time to spend getting the digital feed correct. I doubt Amarillo is going to invest in local digital origination any time soon. They will still be upscaling analog until that million dollar+ budget is approved.