May 31st, 2007
Why HD movie downloads are a big lie
There’s a lot of buzz lately about the delivery of HD TV and Movie content over the Internet with shows like Lost being delivered by ABC.com and other video download services with XBox360 or iTunes. I even have friends and colleagues telling me that BlueRay or HD-DVD won’t make it because HD will simply be delivered over the Internet. But there’s one dirty little secret that people are forgetting or that they don’t understand, IT’S NOT HD they’re getting over the Internet. Heck it’s not even NTSC 480i (720×480 60 fields interlaced) DVD quality when you really look at the amount of video data you’re getting!
Oh sure they might call it HD because it happens to be 1280×720 resolution which sounds awfully high, but you’re talking about an audio/video stream that’s 1.3 mbps (megabits per second) at best. You can call it whatever you like and you can even claim it meets the minimum definition of HD because it’s 720p (1280×720) resolution but it ISN’T HD for the simple reason that the bit rate isn’t enough. A regular 480i DVD is either 2, 5, or 8 mbps and most modern dual-layer 8 GB DVD releases are at least 5 mbps but more likely 8 mbps. A typical DVD movie is approximately 6 GBs of data while a typical “HD” movie you download is only about 1.5 GBs of data. Do you honestly believe you’re getting more image information in that 1.5 GB so-called HD movie you downloaded versus that 6 GB DVD movie?
[Update 3:35PM - I was a bit shocked to hear some people argue that a 1.3 mbps H.264 MPEG-4 based 720p 30-fps video stream can be better than an 8 mbps MPEG-2 480i 60-field DVD stream. I'm going to explain something; it's impossible. MPEG-4 can compress data in a more efficient manner such that it can have a 1.4x advantage over MPEG-2 in compression ratios while maintaining the same perceived quality. However, there's absolutely no way that newer compression formats can overcome a 4 or 6 fold disadvantage in bitrate. Compression - especially in the lossy world of video - is more of a subjective thing. MPEG-2 video is already compressed fairly efficiently and you're really not going to squeeze out any more than a 2 fold improvement at best no matter how fancy the encoder is. There can be marginal improvements in the field of compression but there are never free lunches.]
The fact that a DVD is only encoded in 480i video is unfortunate but it still has more video information and raw potential than a so-called HD movie download for the simple fact that it has 4 times more data. A 480i video stream can be “up-scaled” to a 1080i or 1080p 1920×1080 display with glorious results and I guarantee you that it looks better than that so-called HD 720p movie you spent at least 3 hours downloading over the Internet while your family complains the Internet connection is really slow.
But truthfully speaking, the whole Blu-ray versus HD-DVD format war is silly because a regular dual-layer DVD can easily store 93 minutes of 12 mbps 1080i or 1080p H.264 or VC-1 encoded video with bare minimum HD quality that looks much better than normal MPEG-2 480i DVDs. This format would have been extremely easy to produce and the players could have cost less than $100. The only thing that HD-DVD gets you is that you can either store 3 hours of that same quality video or 100 minutes of good quality 20 mbps H.264 or VC-1 video. Blu-ray players for some reason decided to forego the more advanced video codecs like H.264 or VC-1 and they’re using the old MPEG-2 encoding scheme which neutralized the capacity advantage of Blu-ray media. [UPDATE 6/1/2007 - Newer Blu-ray titles have begun using H.264 so they've regained the capacity lead.] But instead, we have a format war where no one is really winning since Sony decided to cede their market in the next generation console wars with the PS3 to salvage the BlueRay format.Â
Another huge misconception is that people tend to confuse HD movie downloads over the Internet with HD IPTV. While the acronym “IP” stands for “Internet Protocol”, people have the meanings reversed because Internet always involves IP but IP doesn’t always involve the Internet. What I mean by that is that IP could strictly be a closed-network thing on a LAN (Local Area Network).
Note: It’s also a huge misconception that VoIP (Voice over IP) means Voice over the Internet because the vast majority of VoIP traffic happens on the LAN and gets switched over the PSTN (Public Switched Telephone Network).
IPTV requires 16 mbps per HD Channel and it would be IMPOSSIBLE for it to traverse the Internet in unicast traffic in the near tear or long term. IPTV works on a very localized level within a carrier’s own network where everything travels on local fiber-optic multi-gigabit networks on a multicast (or cached) level out to the DSLAM and only from there does it unicast to the user over a mile of a pair of copper cables. [Update 5:50 PM - Think of multicasting as a massive carpool where data is only transmitted once for everyone whereas unicast means the video bandwidth is multiplied by the number of users. Even a 2 mbps unicast stream turns in to a 20,000 mbps stream with 10,000 users where as a multicast or locally cached 16 mbps stream for 100,000 users is still means 16 mbps of traffic over the backbone.] That’s precisely why AT&T U-Verse wants to install miniature DSLAMs within a mile of their customers so they can support a 20 mbps DSL connection that can support a 16 mbps unicast HD IPTV stream over the last mile in addition to data access to the Internet. Other than U-Verse, Verizon’s FiOS (Fiber to the premises or home) is the only other way that IPTV can be delivered to the home. The Cable Internet companies don’t really care about IPTV because they deliver their digital television over a different frequency over the same coax cable and it’s a broadcast technology that sends out the same analog/digital signal to everyone’s house.
This is precisely why HD Movie downloads are a big fat lie being pitched to consumers because even the delivery of 1.3 mbps unicast traffic will bring most parts of the Internet down to its knees if enough people use the service. The carriers are in a strategic position to be close enough to the customer that they can actually deliver true HD-quality IPTV with some level of video on demand and that scares the Googles of the world to death because there’s no way an Internet based 1.3 mbps make-believe HD video service can compete with true HD IPTV. That’s precisely why Google lobbied so hard to defeat the Telecom bill last year which would have deregulated the Telcos so they could implement IPTV and Net Neutrality was merely a political “poison pill” to kill the Telecom bill. More on this later …
George Ou is Technical Director of ZDNet. See his full profile and disclosure of his industry affiliations.
| 05/31/07
