PBS and Ch35 Milwaukee

[techboy]

Does anyone know who to contact at Milwaukee Public TV in regards to technical issues?  I enjoy many of the programs they air, but I'm annoyed by the high level of macro-blocking in any video with quick movement.  Watching "The Real Olympics" was an awful HDTV experience.  They are only using a 17 mbps data stream for the HDTV programs.  That leaves about 2.4 mpbs for other data ( possibly commercial use).  In any case, I'd like to register my complaint where it could do some good.   I'd rather watch good 720p than 1080i transport streamed at low data rates.  When the ATSC system was created, everyone agreed that the entire bandwidth would be necessary for acceptable 1080i.  I noticed WTMJ DT was down to 15 mbps for a while, but have since returned to full stream.

[StarvingForHDTV]

I don't know, but I have noticed the same thing.  If you do get in touch with someone, please tell them to start sending the program guide data over the air like 10-1 does.

Good luck.

[techboy]

Not true.  19.15 is the full spec for the video transport stream.  Audio and PSIP come after that.  WMVT-DT is reserving over 2 mbps for non program data.  This results in blocking of the video because there isn't enough "space" in the stream to compress into mpeg at the full 1920x1080i resolution when the video changes quickly from one frame to the next.  They are trying to cheat the system, and it doesn't work.  Do they want to transmit it high diffinition or not?   A 17mbps stream can only produce full resolution HD if nothing in the picture moves much.  While OK for film, live video quickly suffers a reduced bandwidth stream.

[borghe]

I won't get into their bitrate, all I will say is that an extra 2Mbps (which they technically can't do) will not make the macroblocking go away. It is more a question of recompression than anything else. even if they could encode at a full 19.2Mbps (they can't) there would still be macro blocking.

[wxndave]

The problem that you are seeing is comming from PBS.  If you look at the PBS feed directly you will see the same problem.   Many of the shows that you notice the problems with are upconverted Wide screenshows from PBS.   You can tell the difference because they don't key the PBSHD logo.  If you watch any local production, you will see that there isn't a problem.  I would watch outdoor Wisconsin and see if you can find the problem.

Dave
HDTV Tweaker

[techboy]

I've been watching some of the Olympics on Ch 28 at full 19.15 mbps and I notice some minor macro-blocking there too; mostly on water shots at the pools or fast moving gymnastics.  IT"S THE SYSTEM!!  1080i is a poor choice for sports or any live video.  Squeezing 1080i HDTV into a 6 Mhz TV channel pushes the limits of the encoding technology.  720p is a much better choice for live TV and sports.  That's why ABC and ESPN choose it.  Yes, if we had gotten 10 Mhz channels and 25 Mbps data streams out of the ATSC people and the FCC, 1080i would be the system standard of choice.  But my point is that with 19.15 being questionably adaquate, any data rate lower is unacceptable for live 1080i TV.  Now film is entirely another story.

[StarvingForHDTV]

Originally posted by techboy
I've been watching some of the Olympics on Ch 28 at full 19.15 mbps and I notice some minor macro-blocking there too; mostly on water shots at the pools or fast moving gymnastics.

I saw that as well.  Too bad.  

I prefer 720p for sports also.  Even though I convert it to 1080i before I watch it, it still is reliably better.

Of course anything is better than what CBS did to the "HD" PGA Championship.....