Network Plans

Fox announces that it will go with 720p HDTV!

so progressive is slowly starting to win (as it should)

Progressives Do Very Well

Digital TV Scorecard:   Progressives vs Interlacers

From recent major announcements (see Details and Glossary and Analysis)

Analysis

The data above can be summarized as follows, for the four major networks (omit Department of Defense):

Or, again averaged over the four major networks:

It is important that Congressmen, who will be discussing these results, not pick on Fox for not "correctly" using their free digital spectrum [NB, with the recent news about Fox, 25 Jun 2003, this issue becomes moot].  Clearly, none of the major networks is using the new digital channels for "high definition", if by that they mean more than 480 lines per frame.

It is also important that Congressmen take progressive scan seriously, especially those who still believe - despite numerous strong technical arguments from leading scientists - that 1080i is the only "true" high definition system.  It is clear that the networks are voting for progressive after carefully learning the technologies and their associated costs.  And, by the way, the official ATSC definitions of video formats lists both 720p and 1080i as high definition (hence "true") - consistent with the fact that both deliver the same amount of information per second to the viewer (in other words, pixel count is an incomplete measurement).  See DTV Bandwidths for details - for example, that 720p actually delivers more information than 1080i as practiced.

We encourage Congressmen to please insist on seeing side-by-side demos of the different systems (720p, 1080i, 480p, 480i) to see why we claim that 720p is easily the equivalent of 1080i (actually better since interlace flickers), and that 480p is far superior to today's TV and hence perfectly adequate as a new digital standard for the US.  To call 480p "standard definition" is misleading (see Glossary below).  Again, the networks are voting with their choices.

To be a really good test, we would like for Congressmen to insist on seeing this demo AFTER COMPRESSION, which is what the American consumer will see, not what has been shown Congressmen so far which is BEFORE COMPRESSION.  What you see before compression is what is seen in the studio, not in the home.  It is the very narrow digital channel Congress has allotted to the networks that forces them to compress the signals so severely (about 50:1 for the two high-definition formats!), and this makes a major difference to the quality received in the home.  See DTV Bandwidths for details.

We have made the point again and again, but it is worth stating again:  We do not care what format is used for production, but we care mightily about the transmission format.  So we are still distressed - despite the impressive showing above for progressive scan - that there are ANY networks still seriously considering TRANSMITTING interlaced.  If even one network does, then the consumer is going to have to suffer the expense of conversion to receive all the networks. Again, we argue that conversion of interlace to progressive is, for the consumer, either prohibitively expensive, or of low quality - both of which are avoidable if interlaced TRANSMISSION is simply not used.  (For comparison, conversions between different progressive formats are straightforward, hence inexpensive and high quality). Networks that produce interlaced material should convert it to progressive prior to transmission, at which point they can do a very good job of this tough conversion and not "tax" the consumer.

Details

To make a consistent table of the following detailed facts, I have assumed a 24-hour broadcast day.

DoD = The US Department of Defense which, of course, is not a network.  It is included here because it was an important recent DTV announcement.

ABC and Fox want to be known as All Progressive Networks.

ABC will use 720/60p for 5% of the broadcast day, 7 days a week, as their Prime Time and Special Event format.  Initially this will be 720/24p movies that will be transmitted in a 720/60p "container".  The 480/60p for the remaining 95% will consist mainly of de-interlaced 480/30i obtained from their current main analog feed.  (Progressives approve of de-interlacing as a technique to obtain progressive material so long as it is prior to broadcast, as in this scheme.)

Fox initially announced 480/30p only, but have since discussed adding a 720p format on an experimental basis, probably 720/30p only. [New analysis, added 25 Jun 2003]: New York Times, p C5: "For its high-definition broadcasts, the network will use a 720p transmission, the same as that used by ABC. Proponents say this format, which sends a complete picture 60 times a second, does a better job of reproducing the fast movements of sports. Both NBC and CBS transmit their HDTV programs using the interlaced 1080i format, which alternates sending odd and even lines, and thus sends a complete picture 30 times a second." We highly approve of this decision. It is clear from this news item that Fox plans to use 720/60p.

NBC announced 5 hours per week at 1080/30i, the remainder at 480/60p.  The 480/60p will consist mainly of de-interlaced 480/30i obtained from their current main analog feed.  (See ABC above.)

NBC has consistently maintained that they will continue to evaluate other DTV formats - specifically 720p and 480p of various flavors - and reserve the right to change their preferred HDTV format at some future point, depending on market demand and technology evolution.

CBS has always been adamant about 1080/30i for their HDTV format.  They announced use of it during 5 hours per week.  Their most recent position for SDTV is 480/30i, but earlier reports indicated 480/60p de-interlaced from 480/30i main feed as announced by ABC and NBC.

CBS is also now reporting that they will continue to evaluate other DTV formats and reserve the right to change their definition of HDTV at some future point, depending on market demand and technology evolution.

NBC and CBS and the DoD have publicly maintained that their ultimate goal is to get to 1080/60p = 1080 lines presented progressively 60 times per second.

(Thanks to Tom McMahon, who has been on the front lines, for many of these details.)

Glossary

HDTV = "High Definition" TV = 720 or 1080 lines per frame, regardless of how often, or in what order, they are updated

SDTV = "Standard Definition" TV = 480 lines per frame, regardless of how often, or in what order, they are updated

720/60p = 720 lines presented progressively 60 times per second (one full frame every 1/60th second)

480/60p = 480 lines presented progressively 60 times per second (one full frame every 1/60th second)

480/30p = 480 lines presented progressively 30 times per second (one full frame every 1/30th second)

1080/30i = 540 lines presented interlaced 60 times per second = 1080 lines presented interlaced 30 times per second  (one half frame every 1/60th second, one full frame every 1/30th second)*

480/30i = 240 lines presented interlaced 60 times per second = 480 lines presented interlaced 30 times per second  (one half frame every 1/60th second, one full frame every 1/30th second)*

*These formats are often abbreviated 720p, 480p, 1080i, and 480i. These are misleading abbreviations since they omit the frame rate and tempt the unknowing to compare only the prefix numbers.  I have a proposal that suggests abbreviation 1080i be renamed 540i and 480i be renamed 240i to more faithfully reflect their true characteristics and make comparing only the prefix numbers approximately right.  For example, 540i is not obviously better than 720p (which it isn't) and 240i is easily seen to be poorer than 480p.  It is 240i which is "standard" - that is, like current analog TV - not 480p which is at least twice as good (perceived to be 4-5 times better, however).