November Issue
Dear Gary:
I would like to congratulate you and your staff for the brilliant November issue of Widescreen Review. It definitively ranks amongst the top five best issues of your magazine since I have been reading it (for many, many years). With these kind of in-depth articles, superb evaluations, and great tutorials, you are way ahead of the competition. Keep up the great work.
I read the review of Greg Rogers on the Sony VPL-VW 100 available via the Internet. It is a truly exceptional review and I would not have minded even more in-depth coverage. A thousand congratulations to Greg. One thing which is extremely important for me is that Widescreen Review does not hesitate to list the positives and the negatives or things which could be improved. I am tired of reading all these biased reviews which are simply pre-marketing stuff more or less sponsored by the manufacturers. Please continue to provide us with fair, expert, and honest appraisals.
One need for clarification and one request: In Bill Cruce’s article on the Sony KDS-R60XBR1 Wega rear HDTV, it was not clear whether the TV set accepts native in-coming 1920 x 1080p signals via DVI-HDMI. Bill wrote that this was not the case for such signals coming from a PC source, but he was not explicit about 1080p in-coming video signals.
Greg Rogers wrote in his review that he “hoped” that the studios would select 1080p/24sf as the native resolution of the coming high-definition DVD HD and Blu-ray Disc formats. I believe anything less would not be acceptable (like 1080i/30). With the clout of your magazine and on behalf of our readers, could we push/petition the studios to select 1080p/24sf as the native resolution? It would also be smart for the manufacturers of displays/scalers/players to include a capability to treat the signals in 1080p/72hz (in addition to 1080p/50Hz and 60Hz). This would allow a perfect 3:3 pulldown of the native 1080p/24sf signals.
Two suggestions: Could you explain in a future issue why was 1920 x 1080 selected as the Common Display Format (which, by the way, was a great decision) with the event of D-Cinema and now that a common set of norms have been agreed upon, it may be very relevant that Widescreen Review adds a section on D-Cinema on a regular basis covering the technical and non-technical aspects of it and its implications for non-professional home theatres.
Hervé Girsault, Paris, France
mailto:herve.girsault@wanadoo.fr
Video Technical Editor Greg Rogers Comments:
Thank you for your complimentary remarks about the November issue and my Sony VPL-VW100 review in particular. The answer to your first question is that the Sony KDS-R60XBR1 (reviewed by Bill Cruce in Issue 102) does not accept any 1080p signals.
I like your suggestion for a future article on the 1920 x 1080 Common Image Format, and perhaps it could be expanded into the history of HDTV development, although entire books can be devoted to that subject. But let me give you a brief, simplified answer now about why 1920 x 1080 was an appropriate HDTV format choice.
Two of the goals for HDTV were to provide a wider picture aspect ratio and twice the spatial resolution of existing NTSC, PAL, and SECAM analog broadcast standards. As HDTV standards evolved from analog to digital video, the HDTV format became related to the ITU Rec. 601 standard-definition digital video standard. There are 720 active pixels in each Rec. 601 video line, so 1440 active pixels per line were required to double the horizontal spatial resolution. The 16:9 HDTV aspect ratio (approximately 1.78:1) was selected because it was close to the common 1.85:1 motion picture aspect ratio, and it was mathematically related to the existing 4:3 standard-definition aspect ratio. The 16:9 aspect ratio is exactly 4/3 wider than the 4:3 aspect ratio. Therefore, to maintain the 2x increase in horizontal resolution the number of active pixels per line is 4/3 * 1440 = 1920 pixels per line. It was also decided that HDTV standards should have square pixels (which the standard-definition formats do not have), which means the image aspect ratio is exactly equal to the ratio of the number of horizontal pixels per line to the number of lines. Hence, the number of horizontal lines must be 1920 * 9 / 16 = 1080 lines of pixels.
Note that the 16:9 video aspect ratio is defined by an exact ratio of integers, and digital video and MPEG compression utilize the integer relationships. Therefore, unlike film aspect ratios, the video aspect ratio should be referred to as 16:9 and never 1.78:1. Note that the 1280 x 720 HDTV format is related to the 1920 x 1080 format by the integer ratio 2/3.
Editor-In-Chief and Publisher Comments: I agree with you that the studios should select 1080p/24sf as the native resolution for Blu-ray Disc and HD DVD. We have suggested this approach in previous issues.
While D-Cinema is an important topic, I cannot promise that we will extensively cover it in Widescreen Review.
You can E-mail Widescreen Review @ mailto:editorgary@widescreenreview.com