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Old 02-13-2008, 02:53 AM   #18
damonous damonous is offline
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Oct 2007

Originally Posted by drmpeg View Post
To be honest, I don't have much exposure to compressionists, since my background is almost entirely in real-time encoders for broadcast applications. ...
drmpeg (Ron), thanks for taking the time out for some great info on this Forum. I have a couple of long-burning questions you might be able to answer...

1) Since your background is broadcast application, what do you know of Cable; specifically TWC? I've read unsubstantiated info in the past that Cable providers sometimes re-encode MPEG streams to fit their bandwidth needs. I never used to think this, because compared to my friends' Dish/satellite HD, I've always felt Cable was superior.

But, of late, certain things on TWC in my area (Cleveland) has been looking VERY inconsistent, with some very unexpected 'smelly sights'. In particular, the Super Bowl looked atrocious with gobs of messy macroblocking. Ditto to the Grammys. Other times, I see some absolutely spectacular HD, like Prison Break on Fox (in 1080i even, according to my TV's indicator).

In total, though, all channels seem to be worse (more macroblocking) than in the past. Is it possible that TWC is re-encoding and selectively cranking-down the bits?

2) You posted a page or two back about banding, and I'm curious about what it the primary cause. Is it the bit depth for color, or bit depth for encode, or the codec itself?

Case in point: I recently rented Sunshine on BD. I've always been VERY fond of the quality of Fox/MGM BD's, owning about 15.

For the most part (like 99.99999% ), this was another stunning transfer with spiderweb-fine lines clearly depicting the spaceship's communication arrays, and excellent compression and greyscale control (especially for a film advertised on the sleeve as AVC at only 14mbps!).

Yet, there is one absolutely atrocious moment at the 3/4 mark of the movie, where the ship is moving in space against an eclipse of Mercury against the Sun. Suddenly, a frightening blooming mush of muddy 256-color-looking orange halo around the ship (where a proper haze/mist cloud should have been).

It's a BD50, --so what gives? ...Was the compressionist asleep at the wheel? Is it a limitation of AVC? Is it a limitation of available colorspace?
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