“What sucks about HDTV” is regular feature on the HomeTheaterFocus Blog that will illuminate common complaints, shortcomings and general misconceptions about HDTV. Of course, we all love our HDTV, but many have shelled out thousands on an HD monitor expecting total viewing nirvana only to find its limitations. “What sucks about HDTV” has its own category so you can compile a list of What Sucks About HDTV!
Macroblocking is a phenomena that occurs regularly with HDTV broadcasts, although some material will enhance it’s detrimental effects more than others. It’s particularly noticeable in action movies with lots of fast moving images and bright saturated colors. Anytime something movies quickly on screen it’s likely to suffer from macroblocking on HDTV no matter what kind of movie or TV show. Macroblocking occurs because the high definition images are compressed in Mpeg2 so they can be distributed to your television by cable and satellite TV providers. An HD stream can contain up over 1.3 Gb/sec of information that needs to be compressed (using MPEG) to pass through to cable and satellite TV subscribers. When the compressed video (and audio) reaches the player, such as your set top box, it needs to be uncompressed to your TV’s video input. The upper limit of that decompression rate is 19.4 Mb/sec (with compression factor of more than 60).
You can barely make out Ziyi Zhang taking a lunge at her adversary.
The movie “Hero” (Ying xiong as it’s called in its Chinese release) staring Jet Li and Maggie Cheung is a perfect visual demonstration of the macrblocking phenomena. I’ve taken some sample pictures with a digital camera, I am no photographer so even this “good” image might not do my monitor’s display any justice.
When she’s standing still, the beautiful Maggie Cheung has a clear complexion, as free of compression artifacts and macroblocking as we can expect in HDTV.
But when the action heats up as in this fight scene early on in Hero, two ladies wear bright red fighting among yellow leaves of autumn. The scene would be quite spectacular, a real visual feast of color if not for the horrendous macroblocking that plagues every fight scene in the HD version of this film.
My intention isn't to pick on this particular movie for having a poor transfer to HDTV. Perhaps there is some element of macroblocking that can be attributed to the digitization process before it is ever compressed into mpeg2. But any HDTV show or movie will look this bad while images are moving quickly on screen. I can only hope the implementation of the HD optical disc formats (Blu-Ray and HD DVD) have something better in store than Mpeg2.