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Q G 1 Aspect Ratio and Active Format Description How do we make it all fit? Gerry Field American Public Television St. Paul Public Television Quality Workshop.

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Presentation on theme: "Q G 1 Aspect Ratio and Active Format Description How do we make it all fit? Gerry Field American Public Television St. Paul Public Television Quality Workshop."— Presentation transcript:

1 Q G 1 Aspect Ratio and Active Format Description How do we make it all fit? Gerry Field American Public Television St. Paul Public Television Quality Workshop - July 8-9, 2010

2 Q G 2 Aspect Ratio  Television Aspect Ratio Defined: Picture frame: Ratio of image width to image height. Not directly tied to resolution.  HD Screens are typically 16:9.  SD Screens are both 4:3 and 16:9.  Programming is varied. 16:9, 4:3, 15:9, 14:9, 1.85:1, 2.39:1 etc. Mixed aspect ratio programs

3 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: 2.86.  U.S. homes with three or more TV sets: 54%

4 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 crop other formats  Upconversion, Downconversion

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

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

7 Q G 7 But…How do we make it all fit?  4:3 upconverted to 16:9 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.

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

9 Q G 9 But…How do we make it all fit?  16:9 downconverted 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.

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

11 Q G 11 But…How do we make it all fit?  16:9 can also be “Center Cut” Downconverted 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.

12 Q G 12 16:9 Image

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

14 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.  “Center Cut Safe” – Action and Titles

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

16 Q G 16 16:9 Image center cut to 4:3

17 Q G 17 Worst Case  4x3 Letterbox up converted to 16:9  Then down converted using a 16:9 to 4:3 down converter.  “Postage Stamp”.

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

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

20 Q G 20 Down converted 4:3 Letterbox

21 Q G 21 What is the proper way to treat this?  It depends.  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.

22 Q G 22 Anamorphic  Commonly defines 16:9 “squashed” into 4:3 (Can also apply to 4:3 “stretched” to 16:9)  Used as a distribution technique o Most common is SD widescreen on D-Beta  Must be properly handled prior to emission  If not, viewer sees “squashed” picture

23 Q G 23 Full Screen 16:9

24 Q G 24 Anamorphic 4:3

25 Q G 25 Anamorphic o Anamorphic or 16:9 SD programming may be upconverted to 16:9 HD and distributed (at a bandwidth cost). o Alternatively, 16:9 SD can be distributed with MPEG2 encoder flag set to 16:9. o 16:9 SD included in ATSC A/53 standard. o SD 16:9 can co-exist with SD 4:3 o Member station IRD will output correct format as desired.

26 Q G Source SD 16:9 Sencore IRD MRD3187 16:9 HD or 16:9 SD 4:3 SD Center Cut 4:3, 16:9 Letterbox SD If the MPEG2 flag is set to 16:9 at the MPEG2 Encoder, the Sencore IRD will properly recognize The format and provide properly formatted video

27 Q G 27 Down Converting  Some stations and channels are still SD only.  50 % of our viewers are still SD.  Most HD households still have 2 nd and 3 rd SD sets.

28 Q G 28 Active Format Description - AFD  A four bit code to define the active and protected image area.  Intended to guide professional video equipment, consumer receivers and set-top boxes to optimize the displayed image.  Very few ATSC receivers and consumer decoders act on AFD.

29 Q G 29 Active Format Description - AFD  May also be used for format conversion signaling in the post and pre-broadcast chain.  References: - SMPTE ST 2016-1:2009 - PBS TOS-1, 4.4 - PBS TOS-21, 4.3.7 - PBS Connect > Engineering/Compute > Technical Reference Library

30 Q G 30 AFD Codes  SMPTE ST 2016-1:2009 defines 17 AFD Codes.  Four are in common use:  1000 – Full Frame  1001 – Full 4:3 / Pillarbox  1010 – Protected 16:9  1111 – Center Cuts (14:9, 15:9, 2.35 etc. treated as 16:9)

31 Q G 31 AFD = ‘1000’ (Full Frame) In a 4:3 coded frameIn a 16:9 coded frame

32 Q G 32 AFD = ‘1001’ (Full 4:3 / Pillarbox) In a 16:9 coded frameIn a 4:3 coded frame In a 4:3 coded frame, AFD code ‘1001’ represents the same image display as AFD code ‘1000’. AFD code ‘1000’ is the preferred coding for a full frame 4:3 image

33 Q G 33 AFD = ‘1010’ (Protected 16:9) In a 4:3 coded frameIn a 16:9 coded frame

34 Q G 34 AFD = ‘1111’ (Center Cuts) In a 4:3 coded frameIn a 16:9 coded frame

35 Q G 35 Consumer Issues

36 Q G 36 Consumer Issues o Broadcasters cannot rely on consumers to maintain aspect. o AFD is not widely implemented on consumer devices.

37 Q G 37 So What do we do?  Educate.  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.

38 Q G 38 Questions? / Comments


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