Videokarma.org

Go Back   Videokarma.org TV - Video - Vintage Television & Radio Forums > Television Broadcast Theory

We appreciate your help

in keeping this site going.
Reply
 
Thread Tools Display Modes
  #16  
Old 02-11-2018, 02:38 AM
ppppenguin's Avatar
ppppenguin ppppenguin is offline
VideoKarma Member
 
Join Date: Oct 2009
Location: London, UK
Posts: 236
As old_tv_nut has said, there are so many other variables in the transmission chain it's almost impossible to compare the relative performance of 720p and 1080i in the home.

Interlace was once a wonderful system to reduce bandwidth but it's now just a curse. It's difficult if not impossible to undo it accurately for progressive displays. All flat panel displays are progressive. The best one can say is that receivers have got better, the days of the 2 field splitting apart to give comb shpaed edges on moving objects have largely gone.

[rant] Another curse is the old USA frame rates of 29.97Hz etc. Except they don't affect the home user, only programme makers/distributors. First introduced to cope with NTSC colour (they either had to move the sound subcarrier or frame/line rate to make it work OK) it was a valid choice at the time. That was before timecode. It's been a total PITA ever since, as timecode has to be frigged to make it work with these frame rates. (I'm in a 50Hz country where everything works just fine - I just happen to design kit that has to cope with all standards in the studio.

When HD came in why on earth were the 29.97 etc standards retained? If you needed to re-use old material in a true 30Hz/60Hz standard environment you just played it in 0.1% fast. The madness has been retained in the 4K era, where the SMPTE standards documents still allow for these wretched frame rates. [/rant]
__________________
Jeffrey Borinsky www.borinsky.co.uk
Reply With Quote
  #17  
Old Yesterday, 06:08 PM
Adlershof Adlershof is offline
VideoKarma Member
 
Join Date: Feb 2015
Posts: 19
Quote:
Originally Posted by ppppenguin View Post
Interlace was once a wonderful system to reduce bandwidth but it's now just a curse. It's difficult if not impossible to undo it accurately for progressive displays.
And for this reason public broadcasters in Germany have abandoned production in 720p, in favour of 1080i which they then convert to 720p...

Thus the mentioned discussion.
Reply With Quote
  #18  
Old Today, 12:22 PM
andy's Avatar
andy andy is offline
VideoKarma Member
 
Join Date: Jul 2002
Location: Austin, TX
Posts: 3,949
Quote:
Originally Posted by ppppenguin View Post
...
When HD came in why on earth were the 29.97 etc standards retained? If you needed to re-use old material in a true 30Hz/60Hz standard environment you just played it in 0.1% fast. The madness has been retained in the 4K era, where the SMPTE standards documents still allow for these wretched frame rates. [/rant]
I believe the main reason they don't do that is because of the audio, and for compatibility when editing. You can't just playback digital audio off speed without creating problems, and resampling would be a nightmare (particularly for DD and dts). It would also cause problems when editing since you can't easily make a VCR or other old source play faster.
__________________
Wanted list:
RCA CTC-5
RCA CTC19 or 27
Sony KV-7010U
Reply With Quote
  #19  
Old Today, 04:30 PM
old_tv_nut's Avatar
old_tv_nut old_tv_nut is offline
See yourself on Color TV!
 
Join Date: Jul 2004
Location: Rancho Sahuarita
Posts: 4,424
Digital came in to use piecemeal with islands of digital processing in essentially analog facilities. The digital gear had to mesh with NTSC rates for a long time.
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 06:44 PM.



Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
ęCopyright 2012 VideoKarma.org, All rights reserved.