US OTA DTV Resolutions, 480i/p is?

Archived from groups: alt.tv.tech.hdtv (More info?)

"news.cup.hp.com" <thomasDELME_gilgDELME@hpDELME.com> wrote in message
news:MVaRd.285$%9.0@news.cpqcorp.net...
>
> For US over-the-air DTV, talk of "720p" safely means 1280x720, and "1080i"
> safely means 1920x1080.
>
> Question. For 480i and 480p broadcasts, I swear I'm seeing 720x480,
> 704x480 and 640x480 often, and when analyzing the SD subchannel of the
> recent FOX SuperBowl broadcast, I saw 544x480. The ATSC spec shows 640x480
> and 704x480, so I'm mostly wondering why I'm seeing 720x480 and seemingly
> 544x480 in US OTA DTV broadcasts. What gives? How many issues are arising
> out of non-standard OTA resolutions?
>
> Thomas Gilg
>
Before switching to 720p HD Fox used to distribute a widescreen 480i DTV
format to its stations with the widescreen portion compressed. Stations
could expand the widescreen portion in some programs (480p WS), or broadcast
the video at 4:3. Some stations upconverted to 1080i or 720p. Lots of
variations. For more details, visit avsforum.com and use its search feature
to find relevant posts by foxeng, a fox engineer who has detailed Fox's
formats many times there.
John