The Retailing of HD-DVD and Blu-ray
September 1, 2006,
1080i vs. 1080p
On our tour, one sales rep said pointedly, "The whole world is going 1080p; why would you lock yourself into something that was only 1080i?" It is tough for the typical consumer to argue with that since it makes perfect sense. As one of our readers said in a recent email, "Give me 1080p, 1080p !!! Nothing less will do."
Absolutely. We agree wholeheartedly. The newly emerging, cutting-edge video displays, both projectors and flat panels, are 1080p, or to put it more precisely, they have a physical pixel matrix of 1920x1080, and they are progressively scanned displays. To get the very best performance from these 1080p displays you need a 1080p source.
Contrary to popular misconceptions, HD-DVD and Blu-ray are both 1080p sources. As far as movies are concerned, both disc formats are scanned and encoded in 1080p from the original film. So why the confusion? It comes from the fact that the first HD-DVD player, the Toshiba HD-A1, outputs 1080i, while the first Blu-ray player, the Samsung BD-P1000, outputs both 1080i and 1080p. That sounds like a big deal, but in reality this is more of a marketing/perception problem for the Toshiba player than a technical limitation.
Both HD-DVD and Blu-ray have all of the progressively scanned 1080-lines per frame of information on the disc, and this information is not lost or compromised in 1080i transmission. The transmission interface is simply a matter of the order in which the scanlines are read and transmitted to the video display. If they are transmitted in 1080p, they are sent sequentially. If they are transmitted in 1080i, they are sent in two fields, with one containing the odd numbered lines and another the even numbered lines. These two fields are then reassembled into sequential frames by the video processor in the TV or projector. Either way you end up with the full 1080p frame being used to create the picture, so there is no difference in the end result.
What is not obvious to the consumer is that the Samsung player first converts the 1080p/24 information on the disc to 1080i/60. Once it is in that format, it can output it in either 1080i/60 if that is what the projector or TV takes, or it can convert it to 1080p/60 for output. The Toshiba HD-DVD player converts the 1080p/24 information on the disc to 1080i/60 and simply outputs it in this format. It is then converted to 1080p/60 in the video display. With either player, the signal passes through an interlaced state on its way from the disc to the screen.
Therefore, the 1080p output as implemented on the Samsung BD-P1000 is of no real value to the consumer in terms of enhanced picture quality. It is, however, of tremendous promotional value to Samsung and the Blu-ray group. The extra cost to add 1080p output onto the Samsung BD-P1000 pays handsome returns, because it inspires retail sales reps to say to their customers, "The reason you pay extra for Blu-ray is that it is 1080p, while HD-DVD is only 1080i" Or, as another rep told me last week, "The story is simple: Blu-ray is double the cost and double the resolution."
(By the way, I've never had any indication that comments like these are made with an intent to deceive customers. For the most part, the technologies are just new and there is simply a lot of genuine confusion. The better retailers will no doubt address these issues as time goes on.)
Now, an important side note is warranted. We are talking about the common form of 1080p in the NTSC world, which is 1080p/60. But another way to output the information is to simply transfer the data on the disc in its native 1080p/24 format without doing any conversion to 1080i/60 or 1080p/60. Contrary to what you might expect, 1080p/24 transmission actually can have some incremental benefit over 1080p/60. However, in order to take advantage of 1080p/24 output on the players, we will also need projectors and TVs that can recognize 1080p/24 signals and convert them to 48 or 72 Hz. The vast majority of HD compatible TVs and projectors that have been installed and are being sold today do not have 1080p/24 capability. However, they are beginning to appear in anticipation that Blu-ray and HD-DVD players will be able to output that particular signal format.
The advantage to 1080p/24 transmission is that it can eliminate artifacts associated with the 2:3 pulldown conversion that is common in the NTSC 60 Hz world. The disadvantage is that it adds cost to both the HD disc players and the video display products. Moreover, the vast majority of consumers are not bothered by, or even conscious of the artifacts that it is intended to eliminate anyway. For the most part, 2:3 pulldown conversion is invisible to the viewer except in certain types of scenes, and even then they would not be noticed at a normal viewing distance on most 40" to 50" televisions.
Nevertheless, for videophiles using larger screen systems, 1080p/24 transmission and processing will eliminate 2:3 pulldown artifacts that they can certainly be aware of and bothered by. So as TVs and projectors come onto the market that are able to accept a 1080p/24 signal, both HD-DVD and Blu-ray players will show up that are able to deliver it. In fact, the next wave of higher priced Blu-ray players to hit the market this fall should have 1080p/24 output as an option. A good percentage of the higher end videophile market will be motivated by 1080p/24 transmission, so HD-DVD will need to follow suit in a timely fashion.