Aspect Ratio and Active Format Description How do we make it all fit?. San Francisco Public Television Quality Workshop. Aspect Ratio. Television Aspect Ratio Defined: Ratio of the width of an image to its height. HD Screens are 16:9. SD Screens are 4:3. Programming is ????.
San Francisco Public Television Quality Workshop
Television Aspect Ratio Defined:
Ratio of the width of an image to its height.
HD Screens are 16:9.
SD Screens are 4:3.
Programming is ????.
16:9, 4:3, 15:9, 14:9, 1.85:1, 2.39:1 etc.
We must deal with two display sizes 16:9 and 4:3.
16:9 Sets have over 50% household Penetration.
Number of TV sets in the average U.S. household: 2.86.
Percentage of U.S. homes with three or more TV sets: 54.
There are two programming sizes 16:9 and 4:3.
Treat all widescreen as 16:9 unless we wish to side crop other formats such as 15:9, 14:9, 1.85:1 2.39:1 etc.
4:3 SD up converted to HD Fills the height of the 16:9 frame but leaves blank “pillar boxes” on the sides.
Not a real problem if original quality is high.
16:9 HD Down Converted to 4:3 Fills the width of a 4:3 frame but leaves blank spaces on Top and Bottom.
“Letterboxed” Not perfect for 4:3 but may be acceptable.
16:9 HD can also be “Center Cut” Down Converted to 4:3. This fills the height and width of a 4:3 frame but omits material on the left and right of the original image.
Center Cut is only feasible if all active elements and graphics are maintained in the 4:3 center of the 16:9 image.
Letterbox up converted to 16:9 as a 4:3.
Then down converted using a 16:9 to 4:3 down converter.
There is no incorrect method.
Commercial Networks Up Convert 4:3 with side panels. Down Convert 16:9 by Center Cut.
PBS Stations Up Convert primarily 4:3 with side panels and Down Convert by Center Cutting or Letterboxing.
Full 16:9 “squashed” into a 4:3 frame.
Unacceptable method of distributing HD material.
Unacceptable as a distribution format.
Anamorphic programming must be up converted to 16:9 HD then distributed.
Distributor up converts once as opposed to stations each having to deal with an additional format.
We don’t have to, ATSC is 16X9 HD !
Some stations are still SD only.
50 % of our viewers are still SD.
Most HD households still have 2nd and 3rd SD sets.
A four bit code to define the active and protected image area.
Intended to guide receivers and set-top boxes to optimize the displayed image.
Very few ATSC receivers and consumer decoders act on AFD.
May also be used for format conversion signaling in the post and pre-broadcast chain.
There are 16 AFD Codes.
Realistically only four will be used.
1000 – Full Frame into 16:9 Letterbox.
1001 – 16:9 Center Cut into 4:3 Pillarbox.
1010 – 16:9 Into 4:3 Protected Letterbox
1111 –16:9 image with alternate 4:3 center
14:9, 15:9, 2.35 etc. treat as 16:9.
Letter-box 16:9 into 4:3
As the coded frame
Center cut-out 4:3 from
Letter-box 16:9 into 4:3
(with shoot & protect 4:3 centre)
Centre cut-out 4:3 from
Broadcasters cannot rely on consumers to maintain aspect.
AFD is not widely implemented on consumer devices.
Discuss with Cable and Satellite providers to Implement AFD on their SD Down convert.
Produce when appropriate 16X9 Center cut safe material.
If necessary up convert Letterbox to 16X9 Full frame.