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Discussion Starter · #1 ·
I'm not sure if it is new, but PBS has a new demo loop consisting of several scenery programs produced by KQED and WLIW. The first one is Visions of Greece... and then a couple shorts from KQED showing the SF Bay area... all shot via the helicopters.


Unfortunately the LA PBS station KCET has full-time simulcast of its analog channel, making the HD channel worse looking than VHS tapes!
 

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The KQED "Beautiful Bay Area II : Above the Bay" stuff is a fairly new addition to the loop. Visions of Greece has been with us for a few months. Visions of Greece replaced the old "Vision of Italy South".


I hope PBS rotates in some new "Visions" series later on.


BTW: The KQED stuff was shot years ago. It sat on their shelves for a long time before someone got it included on the loop.
 

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Man, you all are lucky. KCTS in Seattle doesn't play the national loop - heck, their HD channel is only on the air for 4 hours a day, and then is simulcast with their SD feed.
 

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Well that 4 hours is pretty juicy even if they multicast. KCTS seems to have been (at least partly) responsible for the production of the "Over Series" as well as "Smart Travels" and "Chefs Afield". They also did various specials on Seattle, Mt.Ranier, etc.


Many of the shows they put in those 4 hours are ones that other viewers have never seen.
 

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KCTS is also in deep financial do do! Their GM just resigned.
 

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The shots over SF look rather drab, IMHO. Don't know why this is. Perhaps since it was produced several years ago, they used older generation cameras that weren't quite up to current standards.
 

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dandrewk - I think what you said may be true. KQED never actually showed that one in HD on their local channel. They just released it as a DVD to members.


It may not actually be the cameras, but rather the editing equipment they had at the time.
 

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jlin,

Like KCET, KQED also simulcasts an SD channel of their Channel 9 analog content with the HD loop. I notice pixelation/blockiness with fast moving edges more often on this channel than on others that do not simulcast, but it's not too obtrusive. With the high quality content, I pay less attention than usual to the technical picture quality, which also helps. It certainly doesn't look "as bad as VHS tape" quality. I wonder if KCET is experimenting with 1 HD and 3 SD subchannels, like KQED did in their earlier days.


(Or , what kind of VHS player do you have :D ?)


Andy
 

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I used the watch KQED-HD in the early days when it was just a full bitrate single channel. The HD looked noticably better to me that way. It has been a big disappointment that they have resorted to multicasting.
 

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I don't really understand multicasting. Does this mean that in the Fall, if my local OTA ABC station indeed passes on the HD feed of MNF, nevertheless they can be multicasting and I'll hardly recognize it as high definition?? What a disappointment that would be! Please say it ain't so!
 

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ABC broadcasts HD in 720p. The lower resolution of 720p means that it needs less bandwidth for a good picture (as compared to 1080i). ABC can generally multicast one extra SD channel and still have decent 720p on the other.


Video sourced 1080i HD (like PBS) is what really suffers from multicasting.
 

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Kinda off topic, but regarding the multicasting issue, does multicasting only effect people that receive their HD signal over the air? Is multicasting an issue for people who receive their network HD via cable or sat?
 

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Discussion Starter · #13 ·
The "Over the Bay Area" that KQED produced, included as part of the loop, looked particularly bad because it had some fast-moving shots of the ground via the helicopters.


Seriously, it looks worse than VHS tape cuz not only did it lack details but also very pixulated!

Quote:
Originally posted by AJSJones
jlin,

Like KCET, KQED also simulcasts an SD channel of their Channel 9 analog content with the HD loop. I notice pixelation/blockiness with fast moving edges more often on this channel than on others that do not simulcast, but it's not too obtrusive. With the high quality content, I pay less attention than usual to the technical picture quality, which also helps. It certainly doesn't look "as bad as VHS tape" quality. I wonder if KCET is experimenting with 1 HD and 3 SD subchannels, like KQED did in their earlier days.


(Or , what kind of VHS player do you have :D ?)


Andy
 

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Quote:
Is multicasting an issue for people who receive their network HD via cable or sat?
Caught this new loop addition a few weeks back via NYC's Time Warner Cable. The PBS source (WNET-DT) does have a subchannel OTA (PBS Kids), but it appears TWC is getting its feeds via fiber optics. I'm assuming separate 1080i/480i digital feeds to TWC via fibers that should make the 1080i a full 19.39 Mbps. Looks like it, anyway. Superb 1080i fidelity seems the same as before the PBS Kids startup, including the lack of macroblocking during motion/detail scenes.


Perhaps WNET-DT, TWC, and others could deliver fully-resolvable 1080i HDTV . Guess I'd settle for the limiting resolution of 1080i (about 1707 horizontal pixels), referenced in the post link above. Perhaps, since TWC isn't limited to 6-MHz-wide broadcast channels (assuming that and MPEG2 encoders is restricting current OTA HDTV), they could even squeak out 1780 pixels of horizontal resolution. That's what the experts okaying the ATSC system measured for a dynamic 1080i test pattern--not the same as detailed video--back in 1995. -- John
 

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PBS distributes their national feed in OTA ready, ATSC compliant 19.3MBit/sec (unlike many other networks with have their national feed in 45Mbit/sec). So it is doubtful that you will

ever see PBS-HD at more than ATSC bitrate.


Basically no consumers are ever seeing a source greater than ATSC 19.3 unless they watch a D-Theater tape (25Mbit/sec), have a Japan BS player (22Mbit/sec), or they have some sort of commercial grade C-band equipment to catch the national feed for ABC/CBS/NBC.


Those who complain of the KQED segment being badly pixelated may be watching on a local PBS that does do multicasting. It looks much more reasonable at 19Mbit/sec than it does at 15Mbit/sec (or less).


The question of cable/sat versions of OTA being stuck with the multicasting bitrate is an interesting one... I guess it depends.

Many cable systems still use an OTA antenna to receive locals, and then they rebroadcast it to their customers. So in that case they wouldn't have a choice. Some of the bigger cable co's, and the sat co's may be able to get get fiber run directly to the network offices, but I am not sure if they would get to connect in ahead of the stations encoders or not. The station may use the same encoder equipment to split for multicasting & insert their local logo at the same time. In that case they may only provide the reduced bitrate signal to the cable/sat co because they want their logo propagated.
 

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Quote:
Originally posted by PVR
I used the watch KQED-HD in the early days when it was just a full bitrate single channel. The HD looked noticably better to me that way. It has been a big disappointment that they have resorted to multicasting.
What is KQED's intent to multicast the"loop" and normal programming? To meet FCC requirements?


I'd love to lobby them to go back to single band, but my assumption is we might loose the loop in favor of everyday programming.
 

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I am very unimpressed with the KQED segments in the PBS loop. the character graphics look like something out of a highschool video production. The video is much softer than the Visions of Southern Italy segment. Quite frankly after the first 3 minutes of the SF footage I was bored. The flyoever of SF was much less dramatic than any of the Italy or Greece flyover footage. KQED should have gotten out of the chopter and walked through the city. It would have been a good way to show off Fisherman's Warf, Chinatown, and other areas of the city.


-phil
 

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Quote:
Originally posted by duffin
What is KQED's intent to multicast the"loop" and normal programming? To meet FCC requirements?


I'd love to lobby them to go back to single band, but my assumption is we might loose the loop in favor of everyday programming.
Various people have "lobbied" to get them to go back, but they seem entrenched.


I think their internal arguments are something like:


#1: It is now on autopilot. No one has to "throw the switch" everytime national decides to show a unique program

#2: Some capable feeds and apartment buildings distribute KQED to their tennants/customers. Some are finding that the UHF digital SD feed is a better source than the old analog 9 VHF.

#3: PBS national enouraged affiliates to "experiment" with multicasting to test options for the future.

#4: The FCC will require them to give back one of their frequency allocations in the not too distant future. They will either drop chan 9, or chan 30... When that happens they may still want to retain a seperate SD and HD output since they have independent abilties to produce and show programs in either format.
 

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Quote:
Originally posted by PVR

PBS distributes their national feed in OTA ready, ATSC compliant 19.3MBit/sec (unlike many other networks with have their national feed in 45Mbit/sec). So it is doubtful that you will

ever see PBS-HD at more than ATSC bitrate.


Basically no consumers are ever seeing a source greater than ATSC 19.3 unless they watch a D-Theater tape (25Mbit/sec), have a Japan BS player (22Mbit/sec), or they have some sort of commercial grade C-band equipment to catch the national feed for ABC/CBS/NBC.
Seems to me it's still not clear if PBS 1080i fidelity is maxed out with good old ATSC 19.39 Mbps.


I pointed out above that the ATSC approval experts in 1995 measured 1780 pixels with a dynamic test pattern. This, of course, isn't as stringent a test of MPEG-2 encoding fidelity as with detailed motion video from, say, a PBS flyover from KQED.


So it's unclear whether PBS or other stations equipped with the best MPEG-2/ATSC encoders can deliver ~1780, or whether they're limited to 1400, 1500...etc. as generally assumed. You'd think encoder specs would point out such limits, or that some firms would claim a wider range over competitors.


Of course, anything greater than ~1400 calls for adequate displays, and whether the material was taped with Sony HDCAMs that filter >1440. (I'm also assuming home STBs trim final resolution back ~5-17% with reconstruction filters.) But a google.com search suggests some material at PBS and elsewhere was taped originally with Panasonic D5 gear, not filtered at 1440. Videographers mention lugging D5 tape decks--not really as portable as HDCAMs--around the country.


Not so sure consumers won't see >19-Mbps HDTV without special tape, DVD, or satellite access. It would be very easy for cable systems to offer higher bit rates--just pipe one enhanced-fidelity channel (up to 38 Mbps) using 256 QAM down some 6-MHz cable slots instead of the current 2-4 program sources. They're not restricted to any particular codec or transmission scheme. Not enough bandwidth? As cable video on demand use expands, cable companies may boost fiber bandwidth and channel capacity to neighborhood fiber nodes with wave-multiplexing techniques (multiple light wavelengths). -- John
 

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Lots of info on the technical side of this can be found in Joe Kane's article in the current Widescreen Review. It's very good reading.


Todd/Indy
 
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