Claims:We Claim:
Claim 1: A video decoding apparatus for performing, with respect to blocks of spatial frequency data, frequency-transformation by applying a frequency transformation to generate blocks of video data samples which are each scaled, by a common scaling factor, with respect to the video data samples which would result from a normalized frequency-transformation of that block of spatial frequency data, and to dequantize according to a quantization step size, comprising:
circuitry configured to:
apply an n-bit shift to divide data processed by the apparatus by a factor of 2n, where n is an integer;
detect a residual scaling factor, being the common scaling factor divided by 2n;
modify the quantization step size according to the residual scaling factor to generate a modified quantization step size;
multiply each data sample for dequantizing by a value dependent upon the modified quantization step size; and
apply the frequency transformation.

Claim 2: The apparatus according to claim 1, wherein the circuitry is configured to select a quantization index, the quantization index defining a respective entry in a table of quantization step sizes.

Claim 3: The apparatus according to claim 2, wherein the circuitry is configured to change the quantization index so as to select a different quantization step size, such that the ratio of the different quantization step size to the originally selected quantization step size is substantially equal to the residual scaling factor.

Claim 4: The apparatus according to claim 3, wherein the circuitry is configured to select a quantization index in respect of luminance samples and to generate a quantization index offset, relative to the quantization index selected for the luminance samples, for samples of each or both chrominance components; and is configured to change the quantization index offset according to the residual scaling factor.

Claim 5: The apparatus according to claim 2, wherein successive values of the quantization step sizes in the table are related logarithmically, so that a change in quantization index of m (where m is an integer) represents a change in quantization step size by a factor of p (where p is an integer greater than 1).

Claim 6: The apparatus according to claim 5, wherein m = 6 and p = 2.

Claim 7: The apparatus according to claim 6, wherein the data modifier is configured to modify the quantization index by +/- 3.

Claim 8: The apparatus according to claim 6, wherein in which the quantization index is associated with the quantization step and its inverse by one or more tables comprising 1.5m entries.

Claim 9: The apparatus according to claim 8, wherein the quantization index is associated with the quantization step and its inverse by one or both of the following tables:
Index 0 1 2 3 4 5 6 7 8
inverseQStep 26214 23302 20560 18396 16384 14564 12945 11523 10280
scaledQStep 40 45 51 57 64 72 81 91 102

Index -3 -2 -1 0 1 2 3 4 5
inverseQStep 36158 32768 29127 26214 23302 20560 18396 16384 14564
scaledQStep 29 32 36 40 45 51 57 64 72

Claim 10: The apparatus according to claim 1, wherein the data modifier is configured to multiply the quantization step size by a factor dependent upon the residual scaling factor.

Claim 11: Apparatus according to claim 1, in which at least some of the blocks of video data samples comprise MxN samples, where the square root of N/M is not equal to an integer power of 2.

Claim 12: The apparatus according to claim 11, wherein the at least some of the blocks are blocks of chrominance samples.

Claim 13: The apparatus according to claim 12, wherein the video data samples are in a 4:2:2 format.

Claim 14: The apparatus according to claim 1,
wherein the circuitry is configured to matrix-multiply a block of spatial frequency data by a transform matrix and the transposition of the transform matrix, in which the transform matrix comprises an array of integer values which are each scaled by the common scaling factor with respect to respective values of a normalized transform matrix.

Claim 15: The apparatus according to claim 14, wherein the transform matrix comprises an array of integer values which are each scaled with respect to respective values of a normalized transform matrix by an amount dependent upon a dimension of the transform matrix.

Claim 16: The apparatus according to claim 1, wherein
the dequantizing is configured to operate with respect to the blocks of quantized spatial frequency data to generate blocks of dequantized spatial frequency data; and
the circuitry is configured to operate with respect to the blocks of dequantized spatial frequency data to generate blocks of video data samples.

Claim 17: A video coding apparatus for generating blocks of spatial frequency data by performing frequency-transformation on blocks of video data samples and to quantize according to a selected quantization step size, the apparatus comprising:
circuitry configured to:
frequency-transform a block of video data samples to generate a block of spatial frequency coefficients which are each scaled, by a common scaling factor, with respect to the spatial frequency coefficients which would result from a normalized frequency-transformation of that block of video data samples;
select a quantization step size for quantizing; and
apply an n-bit shift to divide by a factor of 2n, where n is an integer;
detect a residual scaling factor, being the common scaling factor divided by 2n;
modify the quantization step size according to the residual scaling factor to generate a modified quantization step size; and
divide each data value for quantizing by a value dependent upon the modified quantization step size and rounding the result to an integer value.

Claim 18: A video decoding method, comprising:
performing with respect to blocks of spatial frequency data, frequency-transformation by applying a frequency transformation to generate blocks of video data samples which are each scaled, by a common scaling factor, with respect to the video data samples which would result from a normalized frequency-transformation of that block of spatial frequency data, and to quantize according to a quantization step size;
applying an n-bit shift to divide data being processed by a factor of 2n, where n is an integer;
detecting a residual scaling factor, being the common scaling factor divided by 2n;
modifying the quantization step size according to the residual scaling factor to generate a modified quantization step size; and
multiplying each of the data samples for dequantizing by a value dependent upon the modified quantization step size; and
applying the frequency-transformation.

Claim 19: A video coding method, comprising:
generating blocks of spatial frequency data by performing frequency-transformation on blocks of video data samples to generate spatial frequency coefficients which are each scaled, by a common scaling factor, with respect to the coefficients which would result from a normalized frequency-transformation of that block of video data samples, and to quantize according to a selected quantization step size;
frequency-transforming a block of video data samples;
selecting a quantization step size for quantizing;
applying an n-bit shift to divide by a factor of 2n, where n is an integer;
detecting a residual scaling factor, being the common scaling factor divided by 2n;
modifying the quantization step size according to the residual scaling factor to generate a modified quantization step size; and
dividing each of the data values for quantizing by a value dependent upon the modified quantization step size and rounding the result to an integer value.

Claim 20: A non-transitory computer readable medium including computer program instructions, which when executed by a computer causes the computer to perform the method of claim 19.

Claim 21: The apparatus according to claim 8, wherein the table includes nine quantization index values each associated with the quantization step and its inverse.

Claim 22: The apparatus according to claim 21, wherein the table includes the following values of quantization index (index), quantization step (scaledQstep) and its inverse (inverseQstep):
Index 0 1 2 3 4 5
inverseQStep 26214 23302 20560 18396 16384 14564
scaledQStep 40 45 51 57 64 72

Claim 23. A video decoding apparatus comprising:
circuitry configured to:
perform with respect to video blocks of spatial frequency data, frequency transformation by applying a frequency transformation to generate blocks of video data samples which are each scaled, and
dequantize by selecting an index value in a table in which for an index value an index scale value is provided,
wherein the index value is selected by performing, by the circuitry, a modulo 6 operation on a quantization parameter, and
wherein the index scale values in the table include values 40, 45, 51, 57, 64 and 72.

Claim 24. The video decoding apparatus according to claim 23, wherein at least some of the values in the table are used for a video block which are not a power of 4 in size.

Claim 25. The video decoding apparatus according to claim 23, wherein the values are quantization step sizes.

Claim 26. The video decoding apparatus according to claim 23, wherein the index value is selected based on whether or not a video block is, or is not, a power of 4 in size and based on the quantization parameter.

Claim 27. A video receiver comprising the video decoding apparatus as claimed in claim 23.

Claim 28. A video capture device comprising a video encoding apparatus and the video decoding apparatus as claimed in claim 23.

Claim 29. A video decoding apparatus comprising:
circuitry configured to
perform, with respect to video blocks of spatial frequency data, frequency transformation by applying a frequency transformation to generate blocks of video data samples which are each scaled, and
dequantize by selecting an index value in a table of six values in which, for an index value, a corresponding index scale is provided,
wherein the index value is selected by performing, by the circuitry, a modulo 6 operation on a quantization parameter, and
wherein at least some of the values in the table are used for coefficients of a video block which are not a power of 4 in size.

Claim 30. The video decoding apparatus as claimed in claim 29, wherein the index scale values in the table include the values 57, 64, and 72.

Claim 31. The video decoding apparatus as claimed in claim 30, wherein the index scale values in the table further include the values 40, 45, and 51.

Claim 32. The video decoding apparatus as claimed in claim 29, wherein the table is stored in a non-transitory storage medium.

Claim 33. A video receiver comprising the video decoding apparatus as claimed in claim 29.

Claim 34. A video capture device comprising a video encoding apparatus and the video decoding apparatus as claimed in claim 29.

Claim 35. A video decoding method comprising:
performing, with respect to video blocks of spatial frequency data, frequency transformation by applying a frequency transformation to generate blocks of video data samples which are each scaled;
dequantizing by selecting an index value in a table in which, for an index value, an index scale value is provided; and
selecting the index value by performing via circuitry a modulo 6 operation on a quantization parameter,
wherein the index scale values in the table include values 40, 45, 51, 57, 64 and 72.

Claim 36. The video decoding method according to claim 35, wherein the values are quantization step sizes.

Claim 37. The video decoding method according to claim 35, further comprising:
selecting the index value based on whether or not a video block is, or is not, a power of 4 in size and based on the quantization parameter.

Claim 38. A non transitory storage medium comprising executable code components which when executed on a computer cause the computer to perform the method of claim 35.

Claim 39. A video decoding method comprising:
performing, with respect to video blocks of spatial frequency data, frequency transformation by applying a frequency transformation to generate blocks of video data samples which are each scaled;
dequantizing by selecting an index value in a table of six values in which, for an index value, a corresponding index scale is provided; and
selecting the index value by performing via circuitry a modulo 6 operation on a quantization parameter,
wherein at least some of the values in the table are used for coefficients of a video block in which are not a power of 4 in size.

Claim 40. The video decoding method as claimed in claim 39, wherein the index scale values in the table include the values 57, 64 and 72.

Claim 41. The video decoding method as claimed in claim 40, wherein the index scale values in the table further include the values 40, 45, and 51.

Claim 42. A non-transitory storage medium comprising executable code components which when executed on a computer cause the computer perform the method according to claim 40.

Dated this: February 18, 2022

[RITAM NARAYAN RAWAL]
IN/PA 2055
Of REMFRY & SAGAR
ATTORNEY FOR THE APPLICANT[S]
, Description:Enclosed