Pixellated display during fast action scenes

[vinny1577]

Hi All,
I've had my Toshiba 46H84 and Comcast HD reception for almost about a
month now. HD programming is an absolute wonder to watch and moveis are
totally life like. I was watching Matrix revolution (2nd one in the series) today which has a lot of fast action action scenes. And I noticed that the display would become really pixellated during these sequences. Once in a while it got really annoying.So is it that:
- my 999$ TV is just not good enough to display these fast action sequences
well?
OR
- It is a problem inherent to RPTVs?
OR
- All kinds of TVs are plagued with this problem?

Thanks,

Vin

[Lobstah]

Some thoughts...
TV and player both doing pulldown? Set tv to film, player to non-progressive
Set TV to 540p instead of 1080i?

Lob

[billbillw]

He didn't say he was watching the DVD. I think he is refering to Comcast (probably HBO HD) In either case, the 540p function only works if you are feeding a 480p signal. Thats not a well know fact, but its burried in the owners manual.

I think his problem is over compression/poor encoding of HBO HD. Their HD movies are less than perfect. Usually they are not as detailed as a well produced DVD.

Some thoughts...
TV and player both doing pulldown? Set tv to film, player to non-progressive
Set TV to 540p instead of 1080i?

Lob

[Lobstah]

Ahhhh...my bad. Thought he was watching DVD.

If it was HBO...then I completely agree.

Lob

[logman]

I had the same problem on TWC showing "Torque" monday. Really huge blocky pixilation any time there was fast moving action. Also on The Rundown last week.

BTW I have a sony kdf50we655

Jim in Houston

[Lobstah]

Welcome to the age of compression :)
Or as someone else's signature asks: "At what bandwidth is HD no longer HD?"

Lob

[57U]

We prefer to call it "macroblocking" and it is caused by the limits of MPEG compression.

See the FAQ on Acronyms for definitions of macroblocking and pixellation.

[Lobstah]

When you say "limits of MPEG compression", exactly what are you referring to?

(I love learning new stuff) :)

Lob

[vinny1577]

Thanks everyone. Yeah, I was watching it on HBO HD (sorry, forgot to mention that). So I guess the problem is with the source material itself. I was just worried if there this is a problem with the TV or if I need to tweak the settings somehow. Will read up the documentation on "macroblocking". But its really interesting that the HDTVs these days can actually make you aware that the source itself is crappy. I would have never seen something like this on my old 27" panasonic :-)

[kdog044]

We prefer to call it "macroblocking" and it is caused by the limits of MPEG compression.It sounds more like temporal dithering. Isn't macroblocking more of a DVD transfer flaw. See below.

http://www.michaeldvd.com.au/Articles/VideoArtefacts/VideoArtefactsMacroBlocking.html

Here is a definition of "temporal dithering".

Temporal dithering is something that most often occurs when you see video with a medium to fast speed pan. There are many theories as to exactly why it happens, but it is not an MPEG artifact, as it goes away when you pause the image, suggesting that it only happens while an image is in motion and is not something that is stored in the original source like a compression artifact.

This appears to be more of a problem with DLP displays.

[57U]

There is obviously one way to tell. If you have a DVR, pause the image, if the compression artifact is still there, then it's macroblocking. If not, then it could be temporal dithering.

Macroblocking is definitely one of the artifacts from MPEG compression and can be seen on fast-moving action or when there are a lot of scene changes. MPEG cannot "keep up" and the blocks are formed. You can also see it in nature shows with falling water, or flocks of birds.

I also thought that temporal dithering affected DLPs. The question was regarding an LCD TV (post 5), so I would rule out temporal dithering. The original post was a CRT-based RPTV and it certainly would not be affected by TD.

[Paleface]

Thanks everyone. Yeah, I was watching it on HBO HD (sorry, forgot to mention that). So I guess the problem is with the source material itself.

Most likely, but there are a couple things you can check to be sure.

First off, make sure you're using a quality component cable for your connection.

Secondly, if you have any splits in your cable line, make sure you're using at least a 900MHz splitter to allow for the HD bandwidth. I first got my HDTV when I lived at my old house and noticed a lot of pixilation. I had split the cable running to my HD with a cheapie $.99 hardware store splitter.

When I moved to my house the cable guy came out and explained to use at least a 900MHz. Now, I still have some pixilation, but not nearly as bad as I used to.