The Magic 8 Ball speaks out on FOX HDTV - More Bits Are HERE!  

Do you know what the new bit rate will be? Since the Splicer HD system does not decode and then encode the signal, I assume that the local stations just retransmit the signal with commercials and logos inserted. I'm not sure how that will work very well in some areas of the country since some Fox affiliates are currently broadcasting 2 multicasting channels on the same band. From earlier tests on my local Fox station, I was getting between 12 mb/s and 14.5 mb/s on the HD channel prior to the increase bit rate.

That is great news, Ken H!

(Kudos, as usual, to the M8B!)

will this make any difference for D* users?

Well I don't understand what they are trying to do then. According to the following article, the local station receiving the stream does not decode and encode but just insert commercials and logos and then rebroadcast the stream.

http://broadcastengineering.com/news...ice/index.html

Have they changed the concept around or am I misunderstanding what it does?

Fox has at least 3-4 separate feeds for primetime programming (East/Central, Mountain, Arizona during DST, and West). Hopefully it means we'll get something more than the barely adequate 7-8mbit/s on some Fox HD primetime shows like 24, but at the very least it should pave the way for more HD baseball and possibly improve the PQ on other Fox sports coverage such as NASCAR.

I expect that they are also using those transponders to transmit the SD channels as well.

Nice to see the M8B doing its thing.....

Each HD stream has a max bit rate of 16 mbps of compatable ATSC data allowing stations to have an additional SD stream if they choose and uses a variable bit rate per stream meaning that for a program that doesn't have much motion, the bit rate is low (8-12 mbps), but a program like the NFL that has lots of movement the bit rate will spike to 16 mbps and this changes automatically by the demand of the content.

FOX has been running several streams per transponder channel, SD and HD totaling 55 mbps. In order to run those efficiently, stat muxing is used. If several of the streams required more bits for certain scenes, it maxed out the system, and I hate to use this term because it has gotten a bad rep here, bit starved the streams at times so FOX has had the stat muxes aggressively working on the bit rates. FOX has been aggressively upgrading receive sites the last 18 months or so to run the higher bit rate so not to bit starve the streams. This upgrade was recently completed as FOX has been using one of the transponders at the higher bit rate for testing for the last year or so allowing the stat muxes to not be so aggressive in their work, making the PQ better.

I personally have only watched a little of some of the video programming and to my eye, it looked better, but I will admit I haven't watched long enough or enough different kind of video to say for sure.

It is amazing how often M8B is correct!!

How long did it take for Fox to switch to HD? 6,7 years?

How long did it take for Fox to offer decent HD? 2 years?

Sounds like they're right on schedule.

Was the 16 mbps pre more bits or what we will see now? If it's what we will see now, why are they not going to 19?

A somewhat wild guess, first-720p generally needs less bandwidth than 1080i for optimum PQ, so 16 mbps should be enough, and second-I'm guessing the left-over is for the stations/affiliates to use for multi-casting/USDTV applications.

Welcome news. Looking forward to seeing it in action.

-Reagan

Ken,

Your points 2 and 3 above lead me to believe that in a world of multicasting, the Fox approach may end up being the best balance for all parties.

There is a fourth benefit: The potential for use of better quality encoders at the head office as compared to the encoders used by each individual station for the other nets.

-R

Also, Fox affiliates don't need DD5.1 encoders, as Fox-Network doesn't send DolbyE.

What's to stop a Fox affiliate from bit rate shaping (or "grooming" as Leitch calls it)? PBS stations do that now.

While I will hold off until we see what is what, the one thing that we never saw on any AVS Thread was "the local station forgot to throw the switch".

Further, as Taz has pointed out with 5.1 audio, the second thing you never saw on AVS is "why is there no dialouge - only sound effects and music" about a Fox local.

Despite being slow to the party - if they do it right - the wait will have made it worth it - especially if they correct the problems that the locals have created for all of us.

They may be slow, but they have seen the problems the others continue to have and possibly to the extent of over control, they have taken away those "gotchas" that the other networks continue to supply us with daily.

Also of note, its interesting to see ABC's new feeds this year moving to the Fox line of thinking instead of discrete feeds for each stream.

Of course, in really its essentially a megapipe distribution which only makes sense from a limited resources concept - as Cinemax, Showtime and others have figured out.

The splicer is last in line and is itself a mux that will take an additional subchannel directly into it not requiring a mux post splicer. This method does create other problems during net such as no way to to super weather, squeeze backs and EAS. To do those, stations have to go back to local upconvert to do those functions. It is my understanding that net is aware of that and is trying to come up with a workable solution.

FOX is very specific where the splicer is placed and can independently interagate the splicers to see what they are doing.

Just a clarification for those who don't know the nomenclature, the 5.1 network audio is fed by the net so a local station doesn't need a 5.1 encoder system, unlike the other networks.

Net has always sent a max of 16 mbps in variable bit rate mode, but with the stat muxing, it caused the PQ to suffer. Net understood that from the beginning, but had to do that until all sites could be upgraded to handle the higher payloads. The only change is the pipe is bigger to handle the 16 mbps better.

But the HD output of the splicer is an ATSC stream correct? Or is it already modulated to 8VSB? Even if it is, the stream could be extracted and "picked". Are there agreements prohibiting this? How would Fox know what's on the output of the splicer other than receiving the stream OTA? I believe Canadian networks receive Fox's fronthaul and decode it to baseband video/audio.

It is a fully compliant ATSC ASI output data stream. It uses PSIP data that must be upstream to mux all of the signals together correctly. Net has a dial in modem they can call the splicer anytime they want and can see what signals are currently available, what mode the splicer is in, and can remotely change modes of the splicer including shut it down, with the stations permission. I don't know how the Canadian networks pick up the HD signal or in what format it is in.

FOX is very specific on how the splicer is to be used and since the equipment belongs to FOX, I guess they can do what they want with it.

Is ABC really switching to this system?
That would be a major development.

-Reagan

Sorry if I'm slow, but how does Fox know what the output of the splicer is hooked up to? Normally I assume it would be a 8vsb modulator, but what's to stop a station (besides agreements) from stripping the mpeg stream, bit rate reducing it and remuxing?

It would be. The Fox splicer system is amazing versatile in that it allows commercials to be very regionalized. I know there are times where a singe station is fed a specific version of a commercial.

That's interesting, because at least here in the West, I've noticed that the HD feed always has the wrong promos for the Saturday MLB game that is airing in this area. Watching the SD and HD feeds side-by-side, the SD will have the correct promo (say, Giants vs Dodgers), while the HD feed may have Yankees vs Red Sox.

What's up with that?

I think the regionalizing is more on SD than HD. This requires extra streams to split and rejoin, and HD is alot more taxing.