So what is high definition TV? Answers vary widely! My own standard would be an image that is at least 720 pixels high (preferably 1920 pixels wide and 1080 pixels high) and is delivered at a reasonable bandwidth. While many services now feature images that large, the bandwidth can really bite.
Here’s what fake HD video looks like by ZDNet‘s George Ou offers an interesting glimpse of how image quality can degrade. I had previously noticed this issue with the high-def channels I used to receive via my local cable company, where macro-blocking and other bandwidth problems were much more visible than in most of the over-the-air digital broadcasts I now view with my rooftop antenna.
Complicating the comparisons is that all high-definition video is heavily compressed using different algorithms, which vary in their efficiency. MPEG2 is commonly used but less capable than the more modern H.264/MPEG4 and VC-1 codecs.
The video options currently available to me at Meador Manor appear to stack up as follows:
|HD-DVD Discs||1920 x 1080i||H.264/VC-1||28|
|Antenna Broadcasts||1920 x 1080i||MPEG2||19.39|
|Apple TV HD Rentals*||1280×720p||H.264||4|
|TiVo Amazon Unbox Rentals||720×480?||VC-1||2.5|
|NetFlix Watch Now||?||?||~1.6-2.2|
*Apple won’t release high-def movie rentals for Apple TV for another week.
One can see that physical media still retain a huge quality advantage over the online options, and I’m very pleased that I now have broadcast HDTV enabled. I don’t know what effective bandwidth my cable TV service was providing for its HD channels, but I would subjectively rate those channels as between DVD and Antenna Broadcasts in the above table, with the cable HD shows occasionally dipping very low in quality with image break-ups.
I won’t be giving up my NetFlix DVD and HD-DVD disc rentals anytime soon, but I have found the Amazon Unbox on my TiVo to be far superior to the NetFlix online streaming service both in picture quality and in convenience. NetFlix is trying to compete with the Amazon/TiVo and Apple TV services by now offering free unlimited streaming to almost all NetFlix customers. But the poor image quality due to limited streaming bandwidth, the occasional hang-ups in the video stream, and the hassle of getting the computer-based images onto the living room TV are huge drawbacks.