Jeremy Charette
01-21-2008, 03:00 PM
<p><img src="http://images.thoughtsmedia.com/resizer/thumbs/size/500/dht/auto/1200877739.usr17787.jpg" border="1" alt="" /></p><p>Over on EngadgetHD I've been having a discussion about bit rates with George Ou of ZDNet. George <a href="http://blogs.zdnet.com/Ou/?p=959">argues</a> that unless the content you are watching is at least 28 mbps 1080p, it's "fake HD". Nevermind that the HD spec. includes resolutions from 1024x768 up to 3840x2160, and that it doesn't specify a bit rate (or rates). He goes on to say that Xbox Live Video Marketplace downloads in HD are "slightly better than DVD but nowhere near 1080i over-the-air HD broadcast quality."</p><p>Unfortunately George's argument is so narrow that he is ignoring several other factors that are for more significant. The real world considerations go far beyond bit rate and resolution. The per pixel bit rate for 720p XBLVM downloads is nearly identical to a 1080i OTA broadcast, and even identical to real world HD DVD bit rates. Granted, the resolution is lower, but the you won't see any added compression artifacts over 1080p HD discs. As it turns out, resolution is a <a href="http://reviews.cnet.com/4520-6449_7-6810011-1.html">non-issue</a> for most people:</p><p>Almost every HDTV in homes today is 720p, not 1080p. The extra resolution available on HD DVD and Blu-Ray is <a href="http://www.hometheatermag.com/gearworks/0105viewvrez/">wasted on most people</a>. What's more, to take advantage of that extra resolution, you'd need:</p><ul> <li>1080p native source (many lower end HD players can only to 1080i or 720p)</li> <li>A 1080p HDTV that can display full resolution with 1:1 pixel mapping</li> <li>Screen size larger than 50"</li> <li>To be sitting closer than 10 feet</li></ul><p>So who can tell the difference given these conditions? Maybe a tenth of a percent of all HDTV owners? A hundredth? Less? Yes, HD DVD and Blu-Ray are better than XBLVM downloads under theoretically ideal circumstances, but the vast majority of people will never notice the difference.</p><p>Then there's the issue of compression algorithms. DVD is encoded in MPEG-2, whereas most HD content is encoded in h.264 or VC-1. To hear George tell it, you'd think they were equals. Fact is the newer codecs result in smaller file sizes, fewer artifacts, and better picture quality. Next thing you know George will be arguing that JPEG should be abolished and all cameras should shoot in RAW.</p><p>It really irks me when people focus on minutiae, rather than taking the big picture into account. Full 1080p video downloads aren't yet practical. There isn't enough bandwidth to make it work. Most of the HDTV sets out there are 720p. In the real world, <a href="http://www.xyhd.tv/2006/12/reviews/why-xbox-live-video-marketplace-competes-well-visually-with-hd-dvd/">Xbox Live downloads are just as good as HD discs</a>. Better yet, you don't have to make a trip to the store to pick one up.</p>