Method and apparatus for adaptively selecting context model for entropy coding

• US 20060233254A1
• Filed: 04/18/2006
• Published: 10/19/2006
• Est. Priority Date: 04/19/2005
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Kyo-hyuk, Cha, Sang-chang, Han, Woo-jin, Lee, Bae-keun
• Granted Patent: US 8,351,502 B2
• Time in Patent Office: Days
• US Class Current: 375/240.160
• CPC Class Codes: H04N 19/13 Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC]
• CPC Class Codes: H04N 19/187 the unit being a scalable video layer
• CPC Class Codes: H04N 19/196 being specially adapted for the computation of encoding parameters, e.g. by averaging previously computed encoding parameters processing of motion vectors H04N19/513
• CPC Class Codes: H04N 19/30 using hierarchical techniques, e.g. scalability H04N19/63 takes precedence
• CPC Class Codes: H04N 19/31 in the temporal domain
• CPC Class Codes: H04N 19/33 in the spatial domain
• CPC Class Codes: H04N 19/34 Scalability techniques involving progressive bit-plane based encoding of the enhancement layer, e.g. fine granular scalability [FGS]
• CPC Class Codes: H04N 19/423 characterised by memory arrangements H04N19/433 takes precedence
• CPC Class Codes: H04N 19/593 involving spatial prediction techniques
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/70 characterised by syntax aspects related to video coding, e.g. related to compression standards

Abstract

A method and apparatus for adaptively selecting a context model for entropy coding and a video decoder are provided. A method of coding a residual prediction flag indicating whether residual data for an enhancement layer block of a multi-layered video signal is predicted from residual data for a lower layer block corresponding to the residual data for the enhancement layer block includes the steps of calculating the energy of the residual data for the lower layer block, determining a coding method for the residual prediction flag according to the energy, and coding the residual prediction flag using the determined coding method.

Claims

1. A method of coding a residual prediction flag indicating whether residual data for an enhancement layer block of a multi-layered video signal is predicted from residual data for a lower layer block corresponding to the residual data for the enhancement layer block, the method comprising:

calculating characteristic data for the lower layer block, wherein the characteristic data comprises at least one of energy of the residual data of the lower layer block and a value of a coded block pattern (CBP) of the lower layer block;

determining a coding method for the residual prediction flag according to the characteristic data; and

coding the residual prediction flag using the determined coding method.

2. The method of claim 1:

wherein if the characteristic data is smaller than a predetermined threshold, the coding of the residual prediction flag is skipped, and if the characteristic data is not smaller than the predetermined threshold, the coding of the residual prediction comprises coding a difference between a predicted value of the residual prediction flag and the residual prediction flag.

3. The method of claim 1, wherein if the characteristic data is not smaller than the predetermined threshold, the coding of the residual prediction flag comprises coding a value of ‘

1’

minus the residual prediction flag.

4. The method of claim 1, wherein if the characteristic data is smaller than the predetermined threshold, the coding of the residual prediction flag is skipped, and if the characteristic data is not smaller than the predetermined threshold, the coding of the residual prediction flag is performed using a context model biased to symbol ‘

1.’

5. The method of claim 1, wherein if the characteristic data is smaller than the predetermined threshold, the coding of the residual prediction flag is performed using a first context model, and if the characteristic data is not smaller than the predetermined threshold, the coding of the residual prediction flag is performed using a second context model, the first context model having higher probability of being ‘

0’

than being ‘

1’ and

the second context model having higher probability of being ‘

1’

than being ‘

0.’

6. The method of claim 1, wherein the lower layer comprises one of a base layer and a fine granularity scalability (FGS) layer.

7. The method of claim 1, wherein:

the energy of the residual data for the lower layer block comprises the number of non-zero pixels in the lower layer block; and

the value of the CBP of the lower layer block comprises the number of bits in the CBP having a value of ‘

1.’

8. The method of claim 1, wherein the value of the CBP comprises values of four (4) less significant bits of the CBP for luminance information called CodedBlockPatternLuma and two (2) more significant bits of the CBP for chrominance information called CodedBlockPatternChroma.

9. The method of claim 1, wherein the calculating of the energy of the residual data comprises summing together the energy of a lower layer that is referred to by the enhancement layer.

10. The method of claim 1, wherein the calculating of the CBP of the lower layer block comprises determined whether each bit of the CBP in the lower layer block has a value of 1.

11. A method of decoding a residual prediction flag indicating whether residual data for an enhancement layer block of a multi-layered video signal is predicted from residual data for a lower layer block corresponding to the residual data for the enhancement layer block, the method comprising:

calculating characteristic data for the lower layer block, wherein the characteristic data comprises at least one of energy of the residual data of the lower layer block and a value of a coded block pattern (CBP) of the lower layer block;

determining a decoding method for the residual prediction flag according to the characteristic data; and

decoding the residual prediction flag using the determined decoding method.

12. The method of claim 11, wherein:

if the characteristic data is smaller than a predetermined threshold, the residual prediction flag is set to “

0”

without decoding the residual prediction flag; and

if the characteristic data is not smaller than the predetermined threshold, the residual prediction flag is set to a difference between a residual prediction difference flag and a predicted value of the residual prediction flag, wherein the residual prediction difference flag corresponds to a difference between the predicted value of the residual prediction flag and the residual prediction flag.

13. The method of claim 11, wherein if the characteristic data is greater than a predetermined threshold, the residual prediction flag is set to a value of ‘

1’

minus a reversed residual prediction flag.

14. The method of claim 11, wherein,

the characteristic data is smaller than a predetermined threshold, the decoding of the residual prediction flag is skipped;

and

if the characteristic data is not smaller than the predetermined threshold, the decoding of the residual prediction flag is performed using a context model biased to symbol ‘

1’

.

15. The method of claim 11, wherein, where the coding of the residual prediction flag has been performed using the context based adaptive binary arithmetic coding (CABAC):

if the characteristic data is smaller than a predetermined threshold, the residual prediction flag is decoded using a first context model; and

if the characteristic data is not smaller than the predetermined threshold, the residual prediction flag is decoded using a second context model, the first context model having higher probability of being ‘

0’

than being ‘

1’ and

the second context model having higher probability of being ‘

1’

than being ‘

0.’

16. The method of claim 11, wherein the lower layer comprises one of a base layer and a fine granularity scalability (FGS) layer.

17. The method of claim 11, wherein

the energy of the residual data for the lower layer block comprises the number of non-zero pixels in the lower layer block;

and

the value of the CBP of the lower layer block comprises the number of bits in the CBP having a value of ‘

1.’

18. The method of claim 11, wherein the value of the CBP comprises values of four (4) less significant bits of the CBP for luminance information called CodedBlockPatternLuma and two (2) more significant bits of the CBP for chrominance information called CodedBlockPatternChroma.

19. The method of claim 11, wherein the calculating of the energy of the residual data comprises summing together the energy of a lower layer that is referred to by the enhancement layer.

20. The method of claim 11, wherein the calculating of the CBP of the lower layer block comprises determining whether each bit of the CBP in the lower layer block that is referred to by the enhancement layer has a value of 1.

21. A method of decoding a residual prediction flag indicating whether residual data for an enhancement layer block of a multi-layered video signal is predicted from residual data for a lower layer block corresponding to the residual data for the enhancement layer block, the method comprising:

checking a value of a coded block pattern (CBP) in the lower layer block;

determining whether or not each bit of the CBP in the lower layer block has a value of ‘

1;

’

determining a decoding method for the residual prediction flag according to whether at least one bit of the CBP in the lower layer block has a value of ‘

1;

’ and

decoding the residual prediction flag according to the determined decoding method.

22. The method of claim 21, wherein the determining whether or not each bit of the CBP has a value of 1 comprises:

setting four (4) less significant bits of the CBP as a first parameter that is used to determine coding of luminance information and two (2) more significant bits as a second parameter that is used to determine coding of chrominance information;

performing a shift-right operation that shifts a bit of the first parameter to the right by an integer selected among ‘

0’

through ‘

3’

allocated to a macroblock address and performing an AND bit operation on ‘

1’

with a result of the shift-right operation, that is ‘

1’

AND the shift-right operation result; and

determining that at least one (1) bit of the CBP has a value of ‘

1’

if a result of the AND bit operation is not ‘

0.’

23. The method of claim 21, wherein the determining of the decoding method comprises setting a context model for decoding the residual prediction flag and the decoding of the residual prediction flag is performed by entropy decoding of the set context model, wherein the entropy decoding is an inverse operation of the CABAC.

24. The method of claim 21, wherein the entropy decoding is performed by context-based adaptive binary arithmetic coding (CABAC).

25. The method of claim 21, wherein the determining of the decoding method comprises:

setting a parameter for selecting a context model to ‘

1’

if there is at least one (1) bit of the CBP having a value of ‘

1;

’ and

setting a parameter for present a context model to ‘

0’

if there is no bit of the CBP having a value of ‘

1.’

26. The method of claim 25, wherein, in the decoding of the residual prediction flag, the residual prediction flag is decoded using:

a first context model having a higher probability of being ‘

0’

than being ‘

1’

if the parameter for selecting the context model is set to ‘

0;

’ and

a second context model having a higher probability of being ‘

1’

than being ‘

0’

if the parameter is set to 1.

27. The method of claim 21, wherein the lower layer comprises one of a base layer and a fine granularity scalability (FGS) layer.

28. The method of claim 21, wherein in the confirming of the CBP of the lower layer block, it is determined whether each bit of the CBP of the lower layer block that is used to predict the enhancement layer has a value of 1.

29. A method of decoding an enhancement layer of a multi-layered video signal comprising:

determining a decoding method for a residual prediction flag indicating whether the enhancement layer is predicted from a lower layer using a value of a coded block pattern (CBP) of a lower layer; and

decoding the residual prediction flag using an entropy decoding method selected according to the decoding method and decoding the enhancement layer using the residual prediction flag.

30. A video encoder for coding a residual prediction flag indicating whether residual data for an enhancement layer block of a multi-layered video signal is predicted from residual data for a lower layer block corresponding to the residual data for the enhancement layer block, the encoder comprising:

a lower layer encoding unit which generates characteristic data for the lower layer block, wherein the characteristic data comprises at least one of energy of the residual data of the lower layer block and a value of a coded block pattern (CBP) of the lower layer block;

an enhancement layer encoding unit which codes the residual prediction flag using a coding method for the residual prediction flag, wherein the method is determined according to the characteristic data.

31. The video encoder of claim 30:

wherein if the characteristic data is smaller than a predetermined threshold, the coding of the residual prediction flag is skipped, and if the characteristic data is not smaller than the predetermined threshold, the coding of the residual prediction comprises coding a difference between a predicted value of the residual prediction flag and the residual prediction flag.

32. The video encoder of claim 30, wherein if the characteristic data is not smaller than the predetermined threshold, the coding of the residual prediction flag comprises coding a value of ‘

1’

minus the residual prediction flag.

33. The video encoder of claim 30:

wherein the coding of the residual prediction flag is performed using the context based adaptive binary arithmetic coding (CABAC); and

wherein if the characteristic data is smaller than the predetermined threshold, the coding of the residual prediction flag is skipped, and if the characteristic data is not smaller than the predetermined threshold, the coding of the residual prediction flag is performed using a context model biased to symbol ‘

1.’

34. The video encoder of claim 30:

wherein the coding of the residual prediction flag is performed using the context based adaptive binary arithmetic coding (CABAC); and

wherein if the characteristic data is smaller than the predetermined threshold, the coding of the residual prediction flag is performed using a first context model, and if the characteristic data is not smaller than the predetermined threshold, the coding of the residual prediction flag is performed using a second context model, the first context model having higher probability of being ‘

0’

than being ‘

1’ and

the second context model having higher probability of being ‘

1’

than being ‘

0.’

35. The video encoder of claim 30, wherein the lower layer comprises one of a base layer and a fine granularity scalability (FGS) layer.

36. The video encoder of claim 30, wherein:

the energy of the residual data for the lower layer block comprises the number of non-zero pixels in the lower layer block; and

the value of the CBP of the lower layer block comprises the number of bits in the CBP having a value of ‘

1.’

37. The video encoder of claim 30, wherein the value of the CBP comprises values of four (4) less significant bits of the CBP for luminance information called CodedBlockPatternLuma and two (2) more significant bits of the CBP for chrominance information called CodedBlockPatternChroma.

38. A video decoder for decoding a residual prediction flag indicating whether residual data for an enhancement layer block of a multi-layered video signal is predicted from residual data for a lower layer block corresponding to the residual data for the enhancement layer block, the decoder comprising:

a base layer decoding unit which generates characteristic data for the lower layer block, wherein the characteristic data comprises at least one of energy of the residual data of the lower layer block and a value of a coded block pattern (CBP) of the lower layer block; and

an enhancement layer decoding unit which decodes the residual prediction flag using a decoding method for the residual prediction flag, wherein the method is determined according to the characteristic data.

39. The video decoder of claim 38:

if the characteristic data is smaller than a predetermined threshold, the residual prediction flag is set to “

0”

without decoding the residual prediction flag; and

if the characteristic data is not smaller than the predetermined threshold, the residual prediction flag is set to a difference between a residual prediction difference flag and a predicted value of the residual prediction flag, wherein the residual prediction difference flag corresponds to a difference between the predicted value of the residual prediction flag and the residual prediction flag.

40. The video decoder of claim 38, wherein if the characteristic data is greater than a predetermined threshold, the residual prediction flag is set to a value of ‘

1’

minus a reversed residual prediction flag.

41. The video decoder of claim 38, wherein, where the coding of the residual prediction flag has been performed using the context based adaptive binary arithmetic coding (CABAC):

the characteristic data is smaller than a predetermined threshold, the decoding of the residual prediction flag is skipped; and

if the characteristic data is not smaller than the predetermined threshold, the decoding of the residual prediction flag is performed using a context model biased to symbol ‘

1’

.

42. The video decoder of claim 38, wherein, where the coding of the residual prediction flag has been performed using the context based adaptive binary arithmetic coding (CABAC):

if the characteristic data is smaller than a predetermined threshold, the residual prediction flag is decoded using a first context model; and

if the characteristic data is not smaller than the predetermined threshold, the residual prediction flag is decoded using a second context model, the first context model having higher probability of being ‘

0’

than being ‘

1’ and

the second context model having higher probability of being ‘

1’

than being ‘

0.’

43. The video decoder of claim 38, wherein the lower layer comprises one of a base layer and a fine granularity scalability (FGS) layer.

44. The video decoder of claim 38, wherein

the energy of the residual data for the lower layer block comprises the number of non-zero pixels in the lower layer block;

and

the value of the CBP of the lower layer block comprises the number of bits in the CBP having a value of ‘

1.’

45. The video decoder of claim 38, wherein the value of the CBP comprises values of four (4) less significant bits of the CBP for luminance information called CodedBlockPatternLuma and two (2) more significant bits of the CBP for chrominance information called CodedBlockPattemChroma.

46. A decoder for decoding a residual prediction flag indicating whether residual data for an enhancement layer block of a multi-layered video signal is predicted from residual data for a lower layer block corresponding to the residual data for the enhancement layer block, the decoder comprising:

a parser which parses a value of a coded block pattern (CBP) for the lower layer block; and

a decoding unit which determines a decoding method for the residual prediction flag according to the value of the CBP and decodes the residual prediction flag using the determined decoding method.

47. The decoder of claim 46, wherein the parser sets four (4) less significant bits of the CBP as a first parameter that is used to determine coding of luminance information and two (2) more significant bits as a second parameter that is used to determine coding of chrominance information, performs a shift-right operation that shifts a bit of the first parameter to the right by an integer selected among ‘

0’

through ‘

3’

allocated to a macroblock address and performs an AND bit operation on ‘

1’

with a result of the shift-right operation, that is ‘

1’

AND the shift-right operation result, and determines that at least one (1) bit of the CBP has a value of ‘

1’

if the result of the AND bit operation is not ‘

0.’

48. The decoder of claim 46, wherein the parser sets a context model for decoding the residual prediction flag and the decoding unit performs entropy decoding using the set context model.

49. The decoder of claim 48, wherein the entropy decoding is context-based adaptive binary arithmetic coding (CABAC).

50. The decoder of claim 46, wherein the parser sets a parameter for selecting a context model to ‘

1’

if there is at least one bit of the CBP having a value of ‘

1’

in the determining of whether each bit of the CBP has a value of ‘

1’

or sets the parameter to ‘

0’

if there is no bit of the CBP having a value of ‘

1.’

51. The decoder of claim 50, wherein the decoding unit decodes the residual prediction flag using:

a first context model having a higher probability of being ‘

0’

than being ‘

1’

if the parameter for selecting the context model is set to ‘

0;

’ and

a second context model having a higher probability of being ‘

1’

than being ‘

0’

if the parameter is set to ‘

1.’

52. The decoder of claim 46, wherein the lower layer comprises one of a base layer and a fine granularity scalability (FGS) layer.

53. The decoder of claim 46, wherein the parser determines whether each bit of the CBP of the lower layer block that is referred to by the enhancement layer has a value of 1.

54. A decoder for decoding an enhancement layer of a multi-layered video signal comprising:

a parser which parses a value of a coded block pattern (CBP) for a lower layer;

an entropy decoding unit which determines a decoding method for a residual prediction flag indicating whether the enhancement layer is predicted from the lower layer using the value of the CBP and performing entropy decoding on the residual prediction flag according to the decoding method and then the enhancement layer;

an inverse quantizer which inversely quantizes the enhancement layer; and

an inverse transformer which performs inverse transform on the inversely quantized enhancement layer according to the residual prediction flag.

55. A coding method performed by a multi-layered video encoder, the coding method comprising:

obtaining a base layer frame from an input frame;

obtaining data for an enhancement layer by referring to reference data comprising at least one of data for the base layer frame, data for a second enhancement layer at a different temporal position and data for a different region of the enhancement layer; and

coding the data for the enhancement layer according to a result of determining whether the data for the enhancement layer is to be predicted from the reference data.

56. The coding method of claim 55, wherein the data for the base layer frame comprises residual data for a base layer frame comprising a residual between the base layer frame and a second frame temporally different from the base layer frame and a motion vector of the base layer frame.

57. The coding method of claim 56, further comprising obtaining energy of the residual data, wherein:

if the energy is smaller than a predetermined threshold, the coding of the data for the enhancement layer comprises coding the data for the enhancement layer without prediction information about whether the data for the base layer frame is to be referred to by the data for the enhancement layer; and

if the energy is not smaller than a predetermined threshold, the coding of the data for the enhancement layer comprises coding the data for the enhancement layer data with the prediction information.

58. The coding method of claim 57, wherein the predetermined threshold is a value obtained when the energy of the residual data is ‘

0.’

59. The coding method of claim 55, further comprising obtaining energy of the residual data, wherein, if the energy of the residual data is not smaller than a predetermined threshold, the coding of the data for the enhancement layer comprises:

calculating a difference between the motion vector of the base layer frame and a motion vector of the enhancement layer;

setting determination information used to predict whether the residual data is to be referred to by the data for the enhancement layer according to the difference between the motion vector of the base layer and the motion vector of the enhancement layer; and

coding the data for the enhancement layer with the determination information and a difference between the determination information and information about whether the residual data is to be referred to by the data for the enhancement layer.

60. The coding method of claim 55, further comprising obtaining a difference between the motion vector of the base layer frame and a motion vector of a spatially adjacent region, wherein:

if the difference is smaller than a predetermined threshold, the coding of the data for the enhancement layer comprises coding the data for the enhancement layer without prediction information about whether the data for the base layer frame is to be referred to by the data for the enhancement layer; and

if the difference is not smaller than a predetermined threshold, the coding of the data for the enhancement layer comprises coding the data for the enhancement layer data with the prediction information.

61. The coding method of claim 60, wherein the predetermined threshold is a value obtained when the residual between the two motion vectors is ‘

0.’

62. The coding method of claim 55, further comprising obtaining a difference between the motion vector of the base layer frame and a motion vector of a spatially adjacent region, wherein, if the difference between the motion vector of the base layer and the other motion vector of the spatially adjacent region is not smaller than a predetermined threshold, the coding of the data for the enhancement layer data comprises:

setting determination information used to predict whether the motion vector of the base layer frame is to be referred to by the enhancement layer data according to the difference between the motion vector of the base layer and the motion vector of the spatially adjacent region; and

coding the data for the enhancement layer with the determination information and a difference between the determination information and information about whether the motion vector of the base layer frame is to be referred to by the data for the enhancement layer.

63. The coding method of claim 55, wherein the data for the enhancement layer comprises determination information used to predict whether the data for the base layer frame is to be referred to by the data for the enhancement layer, and a difference between the determination information and prediction information about whether the data for the base layer frame is to be referred to.

64. The coding method of claim 55, wherein the coding of the data for the enhancement layer data is performed by entropy coding.

65. The coding method of claim 55, wherein the data for the enhancement layer is data for one of a macroblock, a slice, and a frame.

66. A decoding method performed by a multi-layered video decoder, the decoding method comprising:

decoding an input base layer frame;

determining whether data for the base layer frame is needed to predict data for an enhancement layer; and

decoding the data for the enhancement layer according to a result of the determination.

67. The decoding method of claim 66, wherein the data for the base layer frame comprises at least one of residual data for the base layer frame comprising a residual between the base layer frame and a second frame temporally different from the base layer frame and a motion vector of the base layer frame.

68. The decoding method of claim 67, further comprising obtaining energy of the residual data, wherein, in the determining of whether the data for the base layer frame is needed to predict the enhancement layer data:

if the energy is smaller than a predetermined threshold, the decoding of the data for the enhancement layer comprises;

setting first prediction information as indicating that data for the base layer frame was not referred to by the data for the enhancement layer when the data for the enhancement layer was encoded; and

decoding the data for the enhancement layer using the first prediction information; and

if the energy is not smaller than a predetermined threshold, the decoding of the data for the enhancement layer comprises;

setting second prediction information as indicating that the data for the base layer frame was referred to by the data for the enhancement layer when the data for the enhancement layer was encoded; and

decoding the data for the enhancement layer using the second prediction information.

69. The decoding method of claim 68, wherein the predetermined threshold is a value obtained when the energy of the residual data is ‘

0.’

70. The decoding method of claim 67, further comprising obtaining energy of the residual data, wherein, if the energy of the residual data is not smaller than a predetermined threshold, the decoding of the data for the enhancement layer data comprises:

calculating a difference between the motion vector of the base layer frame and a motion vector of the enhancement layer;

setting determination information used to predict whether the residual data is to be referred to by the data for the enhancement layer according to the difference between the motion vector of the base layer and the motion vector of the enhancement layer; and

decoding the determination information and a difference between the determination information and prediction information about whether the residual data is to be referred to by the data for the enhancement layer.

71. The decoding method of claim 67, wherein the decoding of the enhancement layer data comprises:

calculating a motion vector predicted from the data of the base layer frame;

calculating a motion vector predicted from a spatially adjacent region; and

decoding the enhancement layer data by setting prediction information indicating that the enhancement layer data is not predicted from the data of the base layer frame if a residual between the motion vectors is smaller than a predetermined threshold.

72. The decoding method of claim 67, further comprising obtaining a difference between the motion vector of the base layer and a motion vector of an adjacent region, wherein, in the determining of whether the data for the base layer frame is needed to predict the data for the enhancement layer:

if the difference is smaller than a predetermined threshold, the decoding of the data for the enhancement layer comprises;

setting first prediction information as indicating that data for the base layer frame was not referred to by the data for the enhancement layer when the data for the enhancement layer was encoded; and

decoding the data for the enhancement layer using the first prediction information; and

if the difference is not smaller than a predetermined threshold, the decoding of the data for the enhancement layer comprises;

setting second prediction information as indicating that the data for the base layer frame was referred to by the data for the enhancement layer when the data for the enhancement layer was encoded; and

decoding the data for the enhancement layer using the second prediction information.

73. The decoding method of claim 66, wherein the predetermined threshold is a value obtained if the residual between the two motion vectors is ‘

0.’

74. The decoding method of claim 66, further comprising obtaining a difference between the motion vector of the base layer and a motion vector of a spatially adjacent region, wherein, if the difference between the motion vector of the base layer and the motion vector of the spatially adjacent region is not smaller than a predetermined threshold, the decoding of the data for the enhancement layer data comprises:

setting determination information used to predict whether the motion vector of the base layer is to be referred to by the data for the enhancement layer according to the difference between the motion vector of the base layer and the motion vector of the spatially adjacent region; and

decoding the data for the enhancement layer with the determination information and a difference between the determination information and prediction information about whether the data for the enhancement layer is predicted from the motion vector of the base layer frame.

75. The decoding method of claim 66, wherein the data for the enhancement layer comprises determination information used to predict whether the data for the base layer frame is to be referred to by the enhancement layer data, and a difference between the determination information and prediction information about whether the data for the base layer frame is to be referred to.

76. The decoding method of claim 66, wherein the decoding of the data for the enhancement layer is performed by entropy decoding.

77. The decoding method of claim 66, wherein the data for the enhancement layer is data for one of a macroblock, a slice, and a frame.

78. A video encoder comprising:

a base layer encoder which obtains a base layer frame from an input frame; and

an enhancement layer encoder which generates data for an enhancement layer predicted from reference data comprising at least one of data for the base layer frame, data for a second enhancement layer at a different temporal position and data for a different region of the enhancement layer,

wherein the enhancement layer encoder comprises a transformer which codes the data for the enhancement layer according to a result of determining whether the data for the enhancement layer is predictable from the reference data.

79. The encoder of claim 78, wherein the data for the base layer encoder comprises at least one of residual data for the base layer frame comprising a residual between the base layer frame and a second frame temporally different from the base layer frame and a motion vector of the base layer frame.

80. The encoder of claim 79:

wherein the base layer encoder obtains energy of the residual data; and

wherein;

if the energy is smaller than a predetermined threshold, the transformer codes the data for the enhancement layer without prediction information about whether the data for the base layer frame is to be referred to by the data for the enhancement layer; and

if the energy is not smaller than a predetermined threshold, the transformer codes the data for the enhancement layer with the prediction information.

81. The encoder of claim 80, wherein the predetermined threshold is a value obtained when the energy of the residual data is ‘

0.’

82. The encoder of claim 78, wherein the base layer encoder obtains energy of the residual data, and, if the energy of the residual data is not smaller than a predetermined threshold, the transformer:

calculates a difference between the motion vector of the base layer frame and a motion vector of the enhancement layer;

sets determination information used to predict whether the residual data is to be referred to by the data for the enhancement layer according to the difference between the motion vector of the base layer and the motion vector of the enhancement layer; and

codes the data for the enhancement layer data with the determination information and a difference between the determination information and information about whether the residual data is to be referred to by the data for the enhancement layer.

83. The encoder of claim 78:

wherein the transformer calculates a difference between the motion vector of the base layer frame and a motion vector of a spatially adjacent region; and

wherein;

if the difference is smaller than a predetermined threshold, the transformer codes the data for the enhancement layer without prediction information about whether the data for the base layer frame is to be referred to by the data for the enhancement layer

if the difference is not smaller than a predetermined threshold, the transformer codes the data for the enhancement layer with the prediction information.

84. The encoder of claim 83, wherein the predetermined threshold is a value obtained when the residual between the two motion vectors is ‘

0.’

85. The encoder of claim 79:

wherein the transformer obtains a difference between the motion vector of the base layer frame and a motion vector of a spatially adjacent region; and

wherein, if the difference between the motion vector of the base layer and the other motion vector of the spatially adjacent region is not smaller than a predetermined threshold, the transformer;

sets determination information used to predict whether the data for the base layer frame is to be referred to by the data for the enhancement layer according to the difference between the motion vector of the base layer and the motion vector of the spatially adjacent region; and

codes the data for the enhancement layer with the determination information and a difference between the determination information and information about whether the motion vector of the base layer frame is to be referred to by the data for the enhancement layer.

86. The encoder of claim 78, wherein the data for the enhancement layer comprises determination information used to predict whether the data for the base layer frame is to be referred to by the data for the enhancement layer, and a difference between the determination information and prediction information about whether the data for the base layer frame is to be referred to.

87. The encoder of claim 78, wherein the transformer performs entropy coding.

88. The encoder of claim 78, wherein the data for the enhancement layer is data for one of a macroblock, a slice, and a frame.

89. A video decoder comprising:

a base layer decoder which decodes an input base layer frame; and

an enhancement layer decoder which decodes data for an enhancement layer by referring to the base layer frame,

wherein the enhancement layer decoder comprises an inverse transformer which decodes the data for the enhancement layer according to a result of determining whether data for the base layer frame is needed to predict the data for the enhancement layer.

90. The decoder of claim 89, wherein if the data for the base layer frame comprises at least one of residual data for the base layer frame comprising a residual between the base layer frame and a second frame temporally different from the base layer frame and a motion vector of the base layer frame.

91. The decoder of claim 89, wherein the base layer decoder obtains energy of the residual data, wherein:

if the energy is smaller than a predetermined threshold, the inverse transformer;

sets first prediction information as indicating that data for the base layer frame is not referred to by the data for the enhancement layer data when the data for the enhancement layer was encoded; and

decodes the data for the enhancement layer using the first prediction information; and

if the energy is not smaller than a predetermined threshold, the inverse transformer;

sets second prediction information as indicating that the data for the base layer frame is referred to by the data for the enhancement layer when the data for the enhancement layer was encoded; and

decodes the data for the enhancement layer using the second prediction information.

92. The decoder of claim 91, wherein the predetermined threshold is a value obtained when the energy of the residual data is ‘

0.’

93. The decoder of claim 89, wherein if the base layer decoder obtains energy of the residual data and the energy of the residual data is not smaller than a predetermined threshold, the inverse transformer:

calculates a difference between the motion vector of the base layer frame and a motion vector of the enhancement layer;

sets determination information used to predict whether the residual data is to be referred to by the data for the enhancement layer according to the difference between the motion vector of the base layer and the motion vector of the enhancement layer; and

decodes the determination information and a difference between the determination information and prediction information about whether the residual data is to be referred to by the data for the enhancement layer.

94. The decoder of claim 89, wherein the inverse transformer calculates a difference between the motion vector of the base layer frame and a motion vector of a spatially adjacent region, wherein:

if the difference is smaller than a predetermined threshold, the inverse transformer;

sets first prediction information as indicating that data for the base layer frame is not referred to by the data for the enhancement layer data when the data for the enhancement layer was encoded; and

decodes the data for the enhancement layer using the first prediction information; and

if the difference is not smaller than a predetermined threshold, the inverse transformer;

sets second prediction information as indicating that the data for the base layer frame is referred to by the data for the enhancement layer when the data for the enhancement layer was encoded; and

decodes the data for the enhancement layer using the second prediction information.

95. The decoder of claim 94, wherein the predetermined threshold is a value obtained when the residual between the two motion vectors is ‘

0.’

96. The decoder of claim 89:

wherein the inverse transformer obtains a difference between a motion vector of the base layer frame and a motion vector of a spatially adjacent region; and

wherein, if the difference between the motion vector of the base layer and the motion vector of the spatially adjacent region is not smaller than a predetermined threshold, the inverse transformer;

sets determination information used to predict whether the motion vector of the base layer is to be referred to by the data for the enhancement layer according to the difference between the motion vector of the base layer and the motion vector of the spatially adjacent region; and

decodes the data for the enhancement layer with the determination information and a difference between the determination information and prediction information about whether the data for the enhancement layer data is predicted from the motion vector of the base layer frame.

97. The decoder of claim 89, wherein the data for the enhancement layer comprises determination information used to predict whether the data for the base layer frame is to be referred to by the data for the enhancement layer, and a difference between the determination information and prediction information about whether the data for the base layer frame is to be referred to.

98. The decoder of claim 89, wherein the inverse transformer performs entropy decoding.

99. The decoder of claim 89, wherein the data for the enhancement layer is data for one of a macroblock, a slice, and a frame.