Encoding device, decoding device, encoding method, and decoding method for coding efficiency
According to an embodiment, an encoding device includes a deriving unit and an encoding unit. The deriving unit is configured to derive a first reference value based on fixed point precision representing roughness of a weighting factor that is used for multiplying a reference image. The encoding unit is configured to encode a first difference value that is a difference value between the weighting factor and the first reference value and the fixed point precision. The weighting factor is included in a first range of predetermined bit precision having the first reference value at approximate center. The first difference value is in the predetermined range.
1. An electronic apparatus, comprising:
encoder circuitry configured to:
encode a first denom (denominator) for a luma weighting factor;
encode a first difference value that is equal to a value of a difference between the first denominator and a second denominator for a chroma weighting factor;
encode a second difference value of the luma weighting factor, wherein the second difference value is equal to a value of a difference between the luma weighting factor and a first reference value, and the first reference value is equal to a value obtained by left shift of “1” by at least one binary digit specified by the first denominator, and the second difference value is in a fixed range of 128 to +127 regardless of the first denominator;
encode a third difference value of the chroma weighting factor, wherein the third difference value is equal to a value of a difference between the chroma weighting factor and a second reference value, the second reference value is equal to a value obtained by left shift of “1” by at least one binary digit specified by the second denominator, and the third difference value is in a fixed range of 128 to +127 regardless of the second denominator; and
encode a fourth difference value of a chroma offset, wherein the fourth difference value is equal to a value of a difference between the chroma offset and a third reference value, the fourth difference value is in a fixed range of −2 n to +2 n −1, and the third reference value is equal to a value obtained by subtracting a value obtained by both multiplying a median value of a maximum pixel value by the chroma weighting factor and shifting to right for the at least one binary digit specified by the second denominator, from the median value.
2. The electronic apparatus according to claim 1 , wherein:
the value obtained by left shift of “1” by the at least one binary digit specified by the first denominator is equal to a specific luma weighting factor used if a target image had no difference in luma from a reference image.
3. The electronic apparatus according to claim 1 further comprising:
a buffer configured to temporarily store at least part of encoded data; and,
a transmitter configured to transmit the encoded data via a communication link,
wherein the encoder circuitry is a Central Processing Unit (CPU).
4. The electronic apparatus according to claim 1 further comprising:
a buffer configured to temporarily store at least part of encoded data; and,
a transmitter configured to transmit the encoded data via a communication link,
wherein the encoder circuitry is a Digital Signal Processor (DSP) or a Field Programmable Gate Array (FPGA).
5. A encoding method, comprising:
encoding a first denom (denominator) for a luma weighting factor;
encoding a first difference value that is equal to a value of a difference between the first denominator and a second denominator for a chroma weighting factor;
encoding a second difference value of the luma weighting factor, wherein the second difference value is equal to a value of a difference between the luma weighting factor and a first reference value, and the first reference value is equal to a value obtained by left shift of “1” by at least one binary digit specified by the first denominator, and the second difference value is in a fixed range of −128 to +127 regardless of the first denominator;
encoding a third difference value of the chroma weighting factor, wherein the third difference value is equal to a value of a difference between the chroma weighting factor and a second reference value, the second reference value is equal to a value obtained by left shift of “1” by at least one binary digit specified by the second denominator, and the third difference value is in a fixed range of −128 to +127 regardless of the second denominator; and
encoding a fourth difference value of a chroma offset, wherein the fourth difference value is equal to a value of a difference between the chroma offset and a third reference value, the fourth difference value is in a fixed range of −2 n to +2 n −1, and the third reference value is equal to a value obtained by subtracting a value obtained by both multiplying a median value of a maximum pixel value by the chroma weighting factor and shifting to right for the at least one binary digit specified by the second denominator, from the median value.
6. The encoding method according to claim 5 , wherein:
the value obtained by left shift of “1” by the at least one binary digit specified by the first denominator is equal to a specific luma weighting factor used if a target image has no difference in luma from a reference image.
7. The encoding method according to claim 5 , wherein the method further comprises:
temporarily storing, by a buffer, at least part of encoded data; and
transmitting the encoded data via a communication link, and
the encoding of the first denominator, the first difference value, the second difference value, the third difference value, and the fourth difference value are performed by a Central Processing Unit (CPU).
8. The encoding method according to claim 5 , wherein the method further comprises:
temporarily storing, by a buffer, at least part of encoded data; and
transmitting the encoded data via a communication link, and
the encoding of the first denominator, the first difference value, the second difference value, the third difference value, and the fourth difference value are performed by a Digital Signal Processor (DSP) or a Field Programmable Gate Array (FPGA).
9. A non-transitory computer readable medium storing computer executable instructions that, when executed by encoder circuitry, cause the encoder circuitry to:
encode a first denom (denominator) for a luma weighting factor;
encode a first difference value that is equal to a value of a difference between the first denominator and a second denominator for a chroma weighting factor;
encode a second difference value of the luma weighting factor, wherein the second difference value is equal to a value of a difference between the luma weighting factor and a first reference value, and the first reference value is equal to a value obtained by left shift of “1” by at least one binary digit specified by the first denominator, and the second difference value is in a fixed range of −128 to +127 regardless of the first denominator;
encode a third difference value of the chroma weighting factor, wherein the third difference value is equal to a value of a difference between the chroma weighting factor and a second reference value, the second reference value is equal to a value obtained by left shift of “1” by at least one binary digit specified by the second denominator, and the third difference value is in a fixed range of −128 to +127 regardless of the second denominator; and
encode a fourth difference value of a chroma offset, wherein the fourth difference value is equal to a value of a difference between the chroma offset and a third reference value, the fourth difference value is in a fixed range of −2 n to +2 n −1, and the third reference value is equal to a value obtained by subtracting a value obtained by both multiplying a median value of a maximum pixel value by the chroma weighting factor and shifting to right for the at least one binary digit specified by the second denominator, from the median value.
10. The non-transitory computer readable medium according to claim 9 , wherein:
the value obtained by left shift of “1” by the at least one binary digit specified by the first denominator is equal to a specific luma weighting factor used if a target image had no difference in luma from a reference image.