AVS Forum banner
Status
Not open for further replies.
1 - 1 of 1 Posts

· AVS Forum Special Member
Joined
·
11,140 Posts
Discussion Starter · #1 ·
Noticed watching Fox's Star Wars episode last week that images look noticeably better than such films via digital cable (non-HDTV). The next episode, "The Return of the Jedi," is tomorrow night. I tune in Fox's ~480pX704 Star Wars broadcasts using my RPTV's built-in ATSC tuner, which delivers component video internally (see ATSC formats table 2.1 ). And I watch digital cable from a Scientific Atlanta 2000HD's S-video output, deinterlaced by my RPTV to ~480pX720.


Rarely watch 480p OTA here--or progressive DVDs due to an avalanche of premium movies via cable. Curious if others notice similar differences, or differ with this analysis.


With 480X720 digital cable I'm presumably seeing MPEG-2-delivered video with a black-and-white horizontal resolution up to 720 pixels full width on my 16X9 screen. Filtering along the path likely reduces that 720 figure. While cable's S-video and MPEG-2 ensure separated brightness (luminance) and color (chroma) signals, the color portion of the signal is encoded so that it delivers less detail than OTA 480p (next paragraph).


With 480pX704 ATSC from Fox or elsewhere, the horizontal resolution (B&W signal) seems essentially the same as cable's 720 pixels. Overscan on most sets would lop off a fair number of pixels from either source, in addition to possible filtering losses. But the different color encoding of component video (YPrPb) provides considerably more bandwidth than S-video's color. I cited a "Perfect Vision" article in a 8/30/01 post , referring to DVD MPEG-2, indicating component color may have a color bandwidth up to 3 MHz, equating to some 320 color changes on a line across the screen width. Filtering for S-video, the authors said, often shrinks color bandwidth to about 0.5 MHz, or only some 50 color changes per screen width. They describe a means of verifying this using a test DVD.


This all translates, to my eyes, into richer, better-contrasting colors and images when I watch Fox's 480p broadcasts compared to most digital cable. The one non-HDTV exception is CBS's non-HDTV 1080i via the component outputs of my 2000HD cable converter. CBS's daytime broadcasts carried by cable are mostly all upconverted by Snell & Wilcox hardware. This doesn't match 480p sources, IMO, but it's clearly better looking than the analog CBS broadcasts converted to 480p by my RPTV's Genesis circuit. A better enhancement, often prescribed here, is for Fox to begin 720p or 1080i HDTV broadcasts ASAP. -- John
 
1 - 1 of 1 Posts
Status
Not open for further replies.
Top