沒什麼內容的 VP8 簡介

1. Introduction to VP8
郭至軒 (KuoE0)
kuoe0.tw@gmail.com

2. Latest update: Jun 13, 2013
Attribution-ShareAlike 3.0 Unported
(CC BY-SA 3.0)
http://creativecommons.org/licenses/by-sa/3.0/

3. Situation

4. web m

5. web m

6. Video Codec
VP8

7. An
Open
Source
Codec

8. Developed by
On2 Technology

9. Developed by
On2 Technology
February, 2010

10. Acquired by
Google
February, 2010

11. Patent

12. web m

13. March, 2013
web m

14. Royalty-Free TermsMarch, 2013
web m

15. Successor
VP9

16. Successor
VP9
May 15, 2013

17. Feature

18. focus on
Internet
web-based
application

19. Low Bandwidth Requirement
Image Quality:
watchable (PSNR: ~30dB)
visually lossless (PSNR: ~45dB)

20. Heterogeneous Client Hardware

21. Heterogeneous Client Hardware

22. Heterogeneous Client Hardware
Efficient
Implementations

23. Web Video Format
YUV 420 color sampling
8 bit per channel depth
Up to 16383 × 16383 pixels

24. Processing Flow

25. Coding
Predict
Transform + Quantize
Entropy Code
Loop Filter

26. Decoding
Entropy Decode
Predict
Dequantize+Inverse Transform
Loop Filter

27. Reference Frame

28. Golden
Frame
Last Frame
Alternate
Frame
Reference
Frame

29. Golden
Frame
Last Frame
Alternate
Frame
At most 3 reference frames in VP8.

30. Last Frame

31. Last Frame

32. Last Frame

33. Last Frame Current Frame

34. Golden Frame
Choose an arbitrary frame in the past.
Define a number of flags to notify decoder
when and how to update this buffer.

35. Golden Frame
Choose an arbitrary frame in the past.
Define a number of flags to notify decoder
when and how to update this buffer.

38. set as the golden frame

39. Golden Frame
Golden Frame

40. Golden Frame
Golden Frame

41. Golden Frame
Golden Frame

42. Golden Frame
Golden Frame

43. Golden Frame
Golden Frame

44. Golden Frame
Golden Frame

45. Golden Frame
Golden Frame

46. Golden Frame
Golden Frame

47. Golden Frame
Golden Frame

48. Reconstruct
moving object
background

49. Alternate Frame
Other
Frame
Alternate
Frame

50. Alternate Frame
Other
Frame
Alternate
Frame
decode
show

51. Alternate Frame
Other
Frame
Alternate
Frame
decode
show
decode show

52. Alternate Frame
Other
Frame
Alternate
Frame
decode
show
decode show
store beneficial information

53. Construct from multi-frame

54. Construct from multi-frame

55. Construct from multi-frame

56. Construct from multi-frame
Alternate
Frame

57. Typical Frame
I B B P B B P B B I B B P

58. VP8
L G
A
G G G G G L G G G
A
G L

59. Prediction

60. Intra Prediction
Inter Prediction
use data within a single video frame
use data from previously encoded frames

61. Intra Prediction
Luma
Luma
Chroma

62. Intra Prediction
Luma
Luma
Chroma
16 4 8

63. H_PRED (horizontal prediction)
V_PRED (vertical prediction)
DC_PRED (DC prediction)
TM_PRED (TrueMotion prediction)
Four Prediction Modes:

64. Horizontal Prediction
Fills each column of the block with
a copy of the left column.
a b c d e
f g h i j
k l m n o
p q r s t
u v w x y
A B C D E
F G H I J
K L M N O
P Q R S T
U V W X Y

65. Horizontal Prediction
Fills each column of the block with
a copy of the left column.
a b c d e
f g h i j
k l m n o
p q r s t
u v w x y
A B C D E
F G H I J
K L M N O
P Q R S T
U V W X Y
e
j
o
t
y

66. Horizontal Prediction
Fills each column of the block with
a copy of the left column.
a b c d e
f g h i j
k l m n o
p q r s t
u v w x y
A B C D E
F G H I J
K L M N O
P Q R S T
U V W X Y
e
j
o
t
y
e e e e e
j j j j j
o o o o o
t t t t t
y y y y y

67. Vertical Prediction
Fills each row of the block with a
copy of the above row.
a b c d e
f g h i j
k l m n o
p q r s t
u v w x y
A B C D E
F G H I J
K L M N O
P Q R S T
U V W X Y

68. Vertical Prediction
Fills each row of the block with a
copy of the above row.
a b c d e
f g h i j
k l m n o
p q r s t
u v w x y
A B C D E
F G H I J
K L M N O
P Q R S T
U V W X YU V W X Y

69. Vertical Prediction
Fills each row of the block with a
copy of the above row.
a b c d e
f g h i j
k l m n o
p q r s t
u v w x y
A B C D E
F G H I J
K L M N O
P Q R S T
U V W X YU V W X Y
U V W X Y
U V W X Y
U V W X Y
U V W X Y
U V W X Y

70. DC Prediction
Fills the block with a single value
using the average of the pixels in
the above row and the left column.
a b c d e
f g h i j
k l m n o
p q r s t
u v w x y
A B C D E
F G H I J
K L M N O
P Q R S T
U V W X Y

71. DC Prediction
Fills the block with a single value
using the average of the pixels in
the above row and the left column.
a b c d e
f g h i j
k l m n o
p q r s t
u v w x y
A B C D E
F G H I J
K L M N O
P Q R S T
U V W X YU V W X Y
e
j
o
t
y
Z = (U + V + W + X +
Y + e + j + o + t + y) ÷
10

72. DC Prediction
Fills the block with a single value
using the average of the pixels in
the above row and the left column.
a b c d e
f g h i j
k l m n o
p q r s t
u v w x y
A B C D E
F G H I J
K L M N O
P Q R S T
U V W X YU V W X Y
e
j
o
t
y
Z = (U + V + W + X +
Y + e + j + o + t + y) ÷
10
Z Z Z Z Z
Z Z Z Z Z
Z Z Z Z Z
Z Z Z Z Z
Z Z Z Z Z

73. * * * * L0
* * * * L1
* * * * L2
* * * * L3
* * * * L4
* * * * *
* * * * *
* * * * *
* * * * *
A0 A1 A2 A3 A4
TrueMotion Prediction
Horizontal differences
between pixels in
above row and vertical
differences between
pixels in left column are
propagated (starting
from C).
* * * * *
* * * * *
* * * * *
* * * * *
* * * * C

74. * * * * L0
* * * * L1
* * * * L2
* * * * L3
* * * * L4
* * * * *
* * * * *
* * * * *
* * * * *
A0 A1 A2 A3 A4A0 A1 A2 A3 A4
L0
L1
L2
L3
L4
TrueMotion Prediction
Horizontal differences
between pixels in
above row and vertical
differences between
pixels in left column are
propagated (starting
from C).
* * * * *
* * * * *
* * * * *
* * * * *
* * * * CC
Xij = Ai + Lj - C

75. * * * * L0
* * * * L1
* * * * L2
* * * * L3
* * * * L4
* * * * *
* * * * *
* * * * *
* * * * *
A0 A1 A2 A3 A4A0 A1 A2 A3 A4
L0
L1
L2
L3
L4
TrueMotion Prediction
Horizontal differences
between pixels in
above row and vertical
differences between
pixels in left column are
propagated (starting
from C).
* * * * *
* * * * *
* * * * *
* * * * *
* * * * CC
Xij = Ai + Lj - C
Xij Xij Xij Xij Xij
Xij Xij Xij Xij Xij
Xij Xij Xij Xij Xij
Xij Xij Xij Xij Xij
Xij Xij Xij Xij Xij

76. Inter Prediction
As mentioned above...

77. Inter Prediction
Golden
Frame
Last Frame
Alternate
Frame

78. Motion Vector
Reusing vectors from neighboring
macroblocks.
Flexible partitioning of a macroblock into sub-
blocks.

79. Sub-pixel Interpolation
Quarter pixel accurate motion vectors for
luma pixels.
High performance six-tap interpolation
filters.
[3, -16, 77, 77, -16, 3]/128 for 1⁄2 pixel positions
[2, -11, 108, 36, -8, 1]/128 for 1⁄4 pixel positions
[1, -8, 36, 108, -11, 2]/128 for 3⁄4 pixel positions

80. Hybrid Transform
& Quantization

81. Divide into Macroblocks
One 16×16 block of luma pixels (Y)
Two 8×8 blocks of chroma pixels (U, V)
Typical Method

87. 16 8 8

88. Divide into blocks
VP8 Method
All blocks of luma and chroma are 4×4
blocks

91. 4 4 4

92. Discrete Cosine Transform
Fast implementation
Slightly worse in energy compaction
than KLT
Content-independency

93. Coding
2-D DCT
Decoding
4×4 variant of LLM
implementation

94. Coding
2-D DCT
Decoding
4×4 variant of LLM
implementation
Practical fast 1-D DCT algorithms with 11 multiplications

95. I1
I2
I3
I4
O1
O2
O3
O4
Inverse DCT Graph in VP8
y0
y1
x0
x1
y0 = √2(x0×sin(π/8)-x1×cos(π/8))
y1 = √2(x0×cos(π/8)+x1×sin(π/8))

96. H.264/AVC
use multiplication-less integer transform
slightly better than
Energy compaction is

97. It is efficient in processors with
SIMD capability.

98. Walsh-Hadamard Transform
Y = HXHT
H =
1 1 1 1
1 1 -1 -1
1 -1 1 -1
1 -1 -1 1
[ ]HT is the transpose of H.
Take advantage of
the correlation to
reduce redundancy.

99. Adaptive Quantization
128 quantization level.
Different quantization level in single frame.
1st order luma DC
1st order luma AC
2st order luma DC
2st order luma AC
2st order chroma DC
2st order chroma AC

100. Entropy Coding

101. Supports distribution updates on a per-frame
basis
Boolean arithmetic coder
Stable probability distributions within one
frame
Keyframes reset the probability values to the
defaults

102. Adaptive Loop Filter

103. Removing blocking artifacts introduced by
quantization and transformation.

104. Removing blocking artifacts introduced by
quantization and transformation.

105. Removing blocking artifacts introduced by
quantization and transformation.
Slight Filtering

106. Removing blocking artifacts introduced by
quantization and transformation.
Slight Filtering
Strong Filtering

107. Removing blocking artifacts introduced by
quantization and transformation.
Slight Filtering
Strong Filtering
No Filtering

108. Parallel Processing

109. Data Partition
Compressed Data

110. Data Partition
Compressed Data
marcoblock code mode
& motion vector
transform coefficients

111. More Transform Coefficient Partition
transform coefficients
support up to 8 token partitions

112. More Transform Coefficient Partition
transform coefficients
support up to 8 token partitions

113. Compare to H.264

114. 100
120
140
160
180
200
220
240
260
280
300
Night 720p 2000kbps Sheriff 720p 2000kbps Tulip 720p 2000kbps
Deocding speed in Frame/second
VP8 H.264 High Profile
Intel Core i7 3.2GHz

115. 20
25
30
35
40
45
Night 720p 2000kbps Sheriff 720p 2000kbps Tulip 720p 2000kbps
Deocding speed in Frame/second
VP8 H.264 High Profile
Intel Atom N270 1.66GHz

116. Any Questions?

117. Thanks for your listening :)