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A presentation I've created @ RADVISION - Video Conference Solutions. what is between HD and SD conversions? why do objects look fat in HD TV devices? How does your HDTV upscale old SD format? What is the best conversion: stretch/crop/black-bars?
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All you need to know aboutresolutions, PAR, FAR, etc..
Gilad Barkan
SD ? HD ? What is all about?
SD– QCIF– CIF– 4CIF
HD– 720p– 1080p– 480p– 352p– ….
Don’t be confused! HD does not imply bigger than SD!– 352p (HD: 624x352) < 4CIF (SD: 704x576)
4 : 3
16 : 9
FAR = Frame Aspect Ratio
SD ? HD ? What is all about?
SD
– CIF4 : 3
352
288
3
4
288
352
SD ? HD ? What is all about?
SD
– CIF
3
4
9
11
288
352
4 : 3
352
288
SD ? HD ? What is all about?
SD
– CIF
9
11
288
352
PAR = Pixel Aspect Ratio
3
4
11
12
9
11
4 : 3
352
288
Pixel Aspect Ratio = Pixel’s Geometry
SD: PAR = 12:11
1112
100
100
A 100x100 pixels square = A physical 120x110 square
Pixel Aspect Ratio = Pixel’s Geometry
HD : PAR = 1:1
1
1
100
100
A 100x100 pixels square = A physical 100x100 square
The magic formula
FARPAR H
W
9
16
1
1
720
1280
3
4
11
12
288
352CIF 720p
Without PAR handling
Exercise No. 1
Help ?
?
SD HD
A. B. C. D.
Without PAR handling
Exercise No. 1 - Solution
4 .3
6
4 .3
6
SD HD
With PAR handling
Exercise No. 2
A. B. C.
SD HD
?
With PAR handling
Exercise No. 2
SD HD
So how do we convert between them?
352
288
1280
720
SD (4:3) HD (16:9)
5.2288
720 ; 63.3
352
1280
scaling
1. width height
2. 12:11 1:1
Solution 1: Stretch
No loss of data
but No PAR preservation (‘fat’ objects)
352
288
1280
720upscale
SD (4:3) HD (16:9)
Solution 2: Crop
1280
720
352
288
Loss of data
but Preserve PAR
upscale
SD (4:3) HD (16:9)
Solution 3: Black-Bars
No loss of data
and Preserve PAR
but Black in the eyes
1280
720
352
288upscale
SD (4:3) HD (16:9)
Down Scale – Are you still with me?
1280
720
352
288
SD (4:3)HD (16:9)
Solution 1: Stretch
352
288
1280
720
SD (4:3)HD (16:9)
Solution 2: Crop
352
288
1280
720
SD (4:3)HD (16:9)
Solution 3: Black-Bars
352
288
1280
720
SD (4:3)HD (16:9)
Before you leave
FAR– 4:3 (SD)– 16:9 (HD)
PAR– 12:11 (SD)– 1:1 (HD)
Scaling– Down– Up– Modes: stretch / crop / black-bars
FARPAR H
W
Thank You
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