More credit for 720p.....
"The 720p format has been regarded by some camps as the “annoying little brother” of 1080i since the transition to digital television started. Some have even implied that it's not really a true HD format. Only three major networks use it (ABC, Fox, and ESPN), while the rest of the HD world seems to favor 1080i for program acquisition as well as distribution.
But 720p is a Ôfrom scratch' HD format that took advantage of a change from SD to HD to enable progressive picture capture and display. In contrast, 1080i is a legacy format, adapted from the older Japanese 1125-line analog interlaced system.
While it wouldn't be a fair competition between 720p and a 1080-line progressive-scan format with fast picture refresh rates, the fact is that no such camera or broadcast format (1080p/60) exists right now – it would require too much bandwidth or lots of signal compression for distribution, and one heckuva bit rate (over 2 Gb/s uncompressed) for acquisition. (The current 1080p acquisition format uses a 24 Hz frame rate).
Basically, 720p/60 vs. 1080i/30 “shootouts” are pretty even. Consider that, in one frame of a 1080i/30 picture, there are 2,073,600 pixels of picture data. However, that frame consists of two interlaced fields, each refreshing at 1/60 and containing 1,036.800 pixels. A 720p/60 picture has 921,000 pixels refreshing each 1/60 of a second – only 11% less. You'd need a true 1080p display to see any difference.
What's more; 720p has none of the intraframe motion artifacts associated with an interlaced scanning picture capture system. That's one big reason that ABC and ESPN HD decided to use 720p for their live coverage of sporting events, and it's also a big reason why Fox opted to use the format when they started delivering HD programming.
Based on my observations of actual broadcasts and camera tests over the past six years, 720p/60 also tolerates MPEG-2 compression better without introducing such artifacts as mosquito noise and macroblocking that seem to plague 1080i content.
Keep in mind that 720p cameras use full-resolution CCDs with 1280x720 pixels, while 1080i cameras employ CCDs with only 1440x1080 pixels, requiring sub-sampling to pick up the additional 480 horizontal pixels.
Another factor that plays into 720p's favor is the abundance of monitors and TVs with native 720p resolution. Even the biggest proponents of 1080i are now selling flat-panel LCD and plasma monitors that only have 768 vertical lines of picture resolution – LCD monitors up to and including 42” designs are maxed-out at 1280x768 or 1366x768, while plasma monitors don't hit the 1080p count until they are over 65 inches in screen size.
In short, 720p represents a nice camera-to-screen HD solution, and it is exciting news indeed that JVC and Panasonic will have new 720p cameras with 24p, 30p, and ultimately 60p frame rates at the show. If you're attending NAB, try to look at the NAB-HD content on a variety of displays as close as you can get, and see if you think 1080i/30 still has the edge as a “serious” HD format. "
"The 720p format has been regarded by some camps as the “annoying little brother” of 1080i since the transition to digital television started. Some have even implied that it's not really a true HD format. Only three major networks use it (ABC, Fox, and ESPN), while the rest of the HD world seems to favor 1080i for program acquisition as well as distribution.
But 720p is a Ôfrom scratch' HD format that took advantage of a change from SD to HD to enable progressive picture capture and display. In contrast, 1080i is a legacy format, adapted from the older Japanese 1125-line analog interlaced system.
While it wouldn't be a fair competition between 720p and a 1080-line progressive-scan format with fast picture refresh rates, the fact is that no such camera or broadcast format (1080p/60) exists right now – it would require too much bandwidth or lots of signal compression for distribution, and one heckuva bit rate (over 2 Gb/s uncompressed) for acquisition. (The current 1080p acquisition format uses a 24 Hz frame rate).
Basically, 720p/60 vs. 1080i/30 “shootouts” are pretty even. Consider that, in one frame of a 1080i/30 picture, there are 2,073,600 pixels of picture data. However, that frame consists of two interlaced fields, each refreshing at 1/60 and containing 1,036.800 pixels. A 720p/60 picture has 921,000 pixels refreshing each 1/60 of a second – only 11% less. You'd need a true 1080p display to see any difference.
What's more; 720p has none of the intraframe motion artifacts associated with an interlaced scanning picture capture system. That's one big reason that ABC and ESPN HD decided to use 720p for their live coverage of sporting events, and it's also a big reason why Fox opted to use the format when they started delivering HD programming.
Based on my observations of actual broadcasts and camera tests over the past six years, 720p/60 also tolerates MPEG-2 compression better without introducing such artifacts as mosquito noise and macroblocking that seem to plague 1080i content.
Keep in mind that 720p cameras use full-resolution CCDs with 1280x720 pixels, while 1080i cameras employ CCDs with only 1440x1080 pixels, requiring sub-sampling to pick up the additional 480 horizontal pixels.
Another factor that plays into 720p's favor is the abundance of monitors and TVs with native 720p resolution. Even the biggest proponents of 1080i are now selling flat-panel LCD and plasma monitors that only have 768 vertical lines of picture resolution – LCD monitors up to and including 42” designs are maxed-out at 1280x768 or 1366x768, while plasma monitors don't hit the 1080p count until they are over 65 inches in screen size.
In short, 720p represents a nice camera-to-screen HD solution, and it is exciting news indeed that JVC and Panasonic will have new 720p cameras with 24p, 30p, and ultimately 60p frame rates at the show. If you're attending NAB, try to look at the NAB-HD content on a variety of displays as close as you can get, and see if you think 1080i/30 still has the edge as a “serious” HD format. "
