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So just what is 16:9 SD video anyway?
Greetings,
I have a question (or assumption really) regarding the way 16:9 video is handled in the the Standard Def world, particularly in broadcast. First, my limited understanding in the edit world is that 16:9 or “widescreen” video for standard def is really anamorphic video with a raster of 720×480 pixels but with a pixel aspect ratio of 1.2. Therefore the each pixel gets stretched by 1.2 times along the horizontal and the 720 pixels fills a viewable frame size that would be 864×480 (720×1.2=864) if the pixels were square. This concept comes from the cinemascope days of film where the projecting lens had to have the same anamorphic qualities as the taking lens.
My assumption is that the standard def broadcast world is currently operating this way when it sends 16:9 standard def video to my TV set. My tv senses the aspect ratio and switches itself accordingly. I have a 16:9 TV. In other words there is NO BROADCAST standard def format that is 864×480 native with SQUARE PIXELS. Or to put it another way, all broadcast standard def wide screen video is by it’s nature ANAMORPHIC. I know quicktime can do 864×480 square pixels but that’s not my question.
So is my assumption correct or have I made an arse out of you and me!
Many happy returns.
Nate
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4 Replies
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“all broadcast standard def wide screen video is by it’s nature ANAMORPHIC” – Nate
Correct
“standard def is really anamorphic video with a raster of 720×480 pixels” – Nate
Correct for DV output. But… For broadcast the raster size is actually 720 x 486.
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[Dave LaRonde] “There is no such thing as SD widescreen. SD is 4×3. How on earth would you see a complete 16×9 image on a 4×3 screen? See above.”
Fox actually broadcast for a while in Enhanced-Definition Fox Widescreen, which debuted with Super Bowl XXXVI, on its digital broadcasts in 16:9 at 480p ED (even including Dolby Digital 5.1) before offering its current 720p HD format. A show would be run from an anamorphic master, encoded as 16:9 square pixels into an MPEG-2 transport stream, and beamed to your digital 16:9 TV set where the images actually filled the screen!
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Much (but far from all) standard definition analogue PAL in the UK has been broadcast widescreen (or sort-of widescreen) for the last several years by all of the major broadcasters over here, and there have been many widescreen PAL (standard definition) TVs on the market here for a similarly long time.
The UK is in the process of dropping analogue broadcasts. The problem will remain for a while, though, that there’s a mix of TV sets in use, with many (mostly newer) 16×9 screens but still a sizeable number of (mainly older) 4×3 screens. So broadcasters have to find a way to make their output look OK on either type.
To cope with the legacy of lots of 4×3 TV sets, the BBC introduced a policy of originating in 16×9 and passing programmes through an aspect ratio converter to produce a 14×9 programme (with thin black bars top and bottom). A widescreen standard definition TV may need manually setting to 14×9 to view the pictures as intended. Other channels have followed this 14×9 lead.
It took me a while with one US customer to realise he was using “standard definition” to mean “4×3” – not at all a synonym over here!
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My tv senses the aspect ratio and switches itself accordingly.
Your smart TV senses it only if the smart producer/broadcaster has embedded the correct anamorphic signal designator. Sometimes this isn’t done, which is very frustrating.
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