Film-Tech Forum ARCHIVE: HDTV Specs

This is topic HDTV Specs in forum The Afterlife at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=12;t=000180

Posted by Joe Redifer (Member # 3) on 08-07-2003, 09:26 PM:

-How many frames per second can 480p display?

-How many frames per second can 720p display?

-How many fields per second can 1080i display?

-Will there be stupid differences in HDTV from country to country like there is with NTSC, PAL, and SECAM (Suck 'em?)?

Posted by Ron Lacheur (Member # 1126) on 08-08-2003, 03:48 AM:

720p can run at 24, 30 and 60 fps.

1080i can run at 24 and 30 fps.

Posted by Paul Mayer (Member # 355) on 08-08-2003, 04:00 AM:

Well let's see... This is all from the ATSC standards namely the
Digital Televison Standard - Doc. A/53 Rev. B amended 19 May 2003

First here's the Standardized Video Input Formats for ATSC:

Standard ==> Active lines x Active samples/line
SMPTE 274M ==> 1080 (1088) x 1920
SMPTE 296M ==> 720 x 1280
ITU-R BT.601-4 ==> 483 (480) x 720

Then here are the compression format contraints:

V-Size x H-Size | AR Info | Frame Rate | Progressive

1080 x 1920 | 16:9 | 23.976 | Progressive
1080 x 1920 | 16:9 | 24 | Progressive
1080 x 1920 | 16:9 | 29.97 | Progressive
1080 x 1920 | 16:9 | 30 | Progressive
1080 x 1920 | 16:9 | 29.97 | Interlace
1080 x 1920 | 16:9 | 30 | Interlace

720 x 1280 | 16:9 | 23.976 | Progressive
720 x 1280 | 16:9 | 24 | Progressive
720 x 1280 | 16:9 | 29.97 | Progressive
720 x 1280 | 16:9 | 30 | Progressive
720 x 1280 | 16:9 | 59.94 | Progressive
720 x 1280 | 16:9 | 60 | Progressive

480 x 704 | 4:3 or 16:9 | 23.976 | Progressive
480 x 704 | 4:3 or 16:9 | 24 | Progressive
480 x 704 | 4:3 or 16:9 | 29.97 | Progressive
480 x 704 | 4:3 or 16:9 | 30 | Progressive
480 x 704 | 4:3 or 16:9 | 59.94 | Progressive
480 x 704 | 4:3 or 16:9 | 60 | Progressive

480 x 704 | 4:3 or 16:9 | 29.97 | Interlace
480 x 704 | 4:3 or 16:9 | 30 | Interlace

480 x 640 | 4:3 | 23.976 | Progressive
480 x 640 | 4:3 | 24 | Progressive
480 x 640 | 4:3 | 29.97 | Progressive
480 x 640 | 4:3 | 30 | Progressive
480 x 640 | 4:3 | 59.94 | Progressive
480 x 640 | 4:3 | 60 | Progressive

480 x 640 | 4:3 | 29.97 | Interlace
480 x 640 | 4:3 | 30 | Interlace

As you can see there are lots of video format and compression possibilities within the US ATSC standard. Content providers are free to choose from any of these, though market forces and present cost structures have limited the actual choices to a small subset of this list.

As for over-the-air RF modulation standards, the ATSC has gone with 8-VSB (8-level Vestigial Side Band) modulation whereas most of the rest of the world has gone with the European DVB-T's COFDM (Coded Orthogonal Frequency Division Modulation). So the resulting receivers, tuner cards, and STBs (Set Top Box) are incompatible. There was an attempt spearheaded by Sinclair a couple of years back to modify the ATSC standard to allow either 8-VSB or COFDM, based on their tests which showed that 8-VSB wasn't as robust as COFDM in multipath-prone environments (like cities). A couple of manufacturers even started to provide dual-technique STBs and tuner cards in anticipation of this change. But the FCC ultimately rejected the dual technique approach, so 8-VSB is now the only game in the US. Cable uses yet another technique, namely some form of QAM (Quadrature Amplitude Modulation).

Posted by Joe Redifer (Member # 3) on 08-08-2003, 04:36 AM:

Thanks for the detailed info!

Another question (actually two):

-On shows like Jay Leno which are videotaped (and broadcast in some areas) in HDTV, do the sides just get chopped off for standard def TVs?

-I see a lot of letterboxed commercials on TV. Do these automatically zoom or fill the screen when watching on an HDTV or Widescreen SDTV?

Posted by Paul Mayer (Member # 355) on 08-08-2003, 12:41 PM:

Can't answer your second question since I haven't seen enough OTA HDTV to catch that situation. I don't own an HDTV yet, and it will be quite a while before I can afford one.

As to your first question, yes on The Tonight Show the sides of the 16:9 HD image are simply cropped off to create the 4:3 SD image. This is the producer's choice since so many people apparently dislike seeing a 16:9 image letterboxed into a 4:3 display. The camera viewfinders have the 4:3 safe area displayed on them so the operators can frame shots that will work for both formats. Until 16:9 becomes the majority AR for viewers, the sides of the this show's 16:9 image will be used just for fall off.

A quick story. When The Tonight Show began HD production, the SMPTE Hollywood Section organized a tour of the show's new HD facilities. A short presentation about the 14-month project to switch over to HD while still shooting SD was given by the show's Technical Director. During the TD's presentation, Leno decided to crash our little meeting, which was being held on the sound stage. Leno also mentioned all of the efforts spent getting his show ready for HD, and questioned whether the effort had been really worth it. He then asked for a show of hands--how many of us had HD sets at home? Everyone started looking around (there were about 300 of us in there, SMPTE members and guests)--and not one hand went up! The whole room started laughing, since everyone expected to see at least a few hands from this technical crowd. But there were no hands. Leno looked around the room in mock disgust and said "Thank you! I rest my case!" During the tours afterward, the line commonly heard was "We're engineers. We can't afford those HDTV sets!" [Smile]

[ 08-08-2003, 04:00 PM: Message edited by: Paul Mayer ]

Posted by John Pytlak (Member # 331) on 08-13-2003, 09:38 AM:

Links to HDTV information:

http://www.bkprecision.com/docs/hdtv%20standards%20info.pdf

http://www.atsc.org/document_map/video.htm

http://www.atsc.org/standards/a_54.pdf

http://www.shibasoku.co.jp/products/av/hd/tg35bx/atsc-e.html

http://www.miranda.com/library.en/Digital%20Standards/Std_Poster.pdf

Confused? You can always shoot film, which is easily transferred to any video format you need. [Cool]