[Shedrock]

I have been shopping for a new TV, most stores now show an HDTV feed. What I have been noticing is that the background image in a sports event seems to noticeably blur when the camera moves, then there is a pause, then the background is crystal clear again. I have seen this on all types of HDTV's, and different sporting events, such as hockey, tennis, and soccer. I just see this "blur, pause, focus,...repeat" pattern.


Am I correct in assuming that this is caused more by the camera that is filming the action, than the TV display? It would make sense that a sudden camera movement could momentarily overload the digital storage capability of the HDTV camera.


Any of your thoughts on this would be appreciated.

 

[bfdtv]

Shedrock,


There aren't any pauses that I know of in actual live telecasts, so I'm not sure what you are talking about there. But with 1080i HDTV, there is some blurring in fast movement, particularly when required bandwidth exceeds that available to the channel. With 720p/60 HDTV sports (on ABC, ESPN-HD), there is less detail / resolution per frame, but should also be less of the blurring, because it is 60 frames per second rather than 30. It is for that reason that some people prefer the 720p HDTV resolution for sports, even though it offers less detail on slow moving and static pictures.

 

[drhill]

I don't see why 30 fps interlaced causes problems in sports. That's what we've been using for years now. I would think the problem would arise from not enough bandwidth or within the encoding process itself. So personally, I prefer 1080 because I imagine that the situation will get better.


Now I would prefer 60 fps over 30. Anyone who seriously plays video games (console or pc) knows that at every resolution higher frame rate is better for smoothness and seems more vivid.


Although I would argue that 60 isn't enough. First it must be consistently 60 (never!!! any dips under 60), but also I notice a difference when I change refresh rates on a computer monitor from 60 to 72. And it's quite a difference.

 

[bfdtv]

drhill,


That's certainly true; artifacting associated with fast motion has a lot to do with the compression, and this should get better over time as real-time broadcast HD encoders improve. Obviously, 720p also requires less bandwidth, so there should be fewer compression artifacts when a comparable bit rate is used.

 

[DonBerg]

Its due to the MPEG2 compression. With MPEG2, the picture quality varies - with a still image or slow motion, quality is high and when there is fast mostion the quality is lowered to maintain an average bitrate that is limited. I have found 720p is better for fast motion than 1080i, I see fewer lower quality artifacts like macroblocks from fast motion with 720p. In any case this has nothing to do with the display or camera, its due to the compression mechanism used - its the same with DVD too, but they apparently use sufficient bitrate at its lower resolution so the artifacts are less apparent with most DVD movies.

 

[drhill]

So for now 720p is better. I suppose HD-dvd won't have any problems either (for 1080 as long as blue ray is used).


I've noticed on comcast sportsnet-hd for flyers games I see no problems, phillies don't seem to exhibit any problems either.


For sixers games there is some artifacts. Seems to be quick arm movements where the background is much darker (ex: around the rim where from the camera you see the crowd). But this really isn't distracting so I prefer the added resolution with a small amount of artifacts better.


Although, I haven't seen native 720p, and my cable box's conversion is a bit soft. It's a shame manufacturers don't all support both resolutions, but it's an obvious cost concern.

 

[Shedrock]

DonBerg,


You seem to have answered my original question.


Thanks!