Q G 1 Aspect Ratio and Active Format Description How do we make it all fit? San Francisco Public Television Quality Workshop

Q G 2 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 ????.  16:9, 4:3, 15:9, 14:9, 1.85:1, 2.39:1 etc.

Q G 3 How do we make it all fit?  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:  Percentage of U.S. homes with three or more TV sets: 54.

Q G 4 How do we make it all fit?  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.

Q G 5 4:3 Image in a 4:3 Display

Q G 6 16:9 Image in a 16:9 Display

Q G 7 But…How do we make it all fit?  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.

Q G 8 4:3 Image in a 16:9 Frame

Q G 9 But…How do we make it all fit?  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.

Q G 10 16:9 Image “Letterboxed” in 4:3 Frame

Q G 11 But…How do we make it all fit?  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.

Q G 12 16:9 Image

Q G 13 16:9 Center Cut in 4:3 Frame

Q G 14 However…..  Center Cut is only feasible if all active elements and graphics are maintained in the 4:3 center of the 16:9 image.

Q G 15 16:9 Image in a 16:9 Display

Q G 16 16:9 Image Center cut Artifacting

Q G 17 Worst Case  Letterbox up converted to 16:9 as a 4:3.  Then down converted using a 16:9 to 4:3 down converter.  “Postage Stamp”.

Q G 18 16:9 Image in a 4:3 Display

Q G 19 Up Converted to 16:9 as 4:3

Q G 20 Down converted 4:3 Letterbox

Q G 21 What is the proper way to do this?  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.

Q G 22 Full Screen 16:9

Q G 23 Anamorphic 4:3

Q G 24 Anamorphic  Full 16:9 “squashed” into a 4:3 frame.  Unacceptable method of distributing HD material.  Unacceptable as a distribution format.

Q G 25 Anamorphic  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.

Q G 26 Down Converting  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 2 nd and 3 rd SD sets.

Q G 27 Active Format Description - AFD  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.

Q G 28 Active Format Description - AFD  May also be used for format conversion signaling in the post and pre-broadcast chain.

Q G 29 AFD Codes  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.

Q G – Full Frame into 16:9 Letterbox As the coded frame Letter-box 16:9 into 4:3 scan

Q G – 16:9 Center Cut into 4:3 Pillar-box 4:3 (center) Center cut-out 4:3 from 16:9

Q G – 16:9 Into 4:3 Protected Letterbox 16:9 (center) Letter-box 16:9 into 4:3 scan

Q G –16:9 image with alternate 4:3 center 16:9 (with shoot & protect 4:3 centre) Centre cut-out 4:3 from 16:9

Q G 34 Consumer Issues

Q G 35 Consumer Issues  Broadcasters cannot rely on consumers to maintain aspect.  AFD is not widely implemented on consumer devices.

Q G 36 So What do we do?  Implement AFD.  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.

Q G 37 Questions? / Comments