Video signal coding apparatus and video signal coding method
Video signal coding apparatus includes a quantization unit which quantizes a luminance signal of each of a first picture and a second picture coded after the first picture, and quantizes a chrominance signal of each of the first picture and the second picture. A code amount obtainment unit obtains a luminance code amount and a chrominance code amount of each of the first picture and the second picture; and a rate calculation unit calculates a rate of the chrominance code amount with respect to the luminance code amount for each of the first picture and the second picture. A rate control unit changes a coefficient value of at least one of the first matrix and the second matrix used in quantizing the second picture, before the quantization unit quantizes the second picture, so that the rate for the second picture becomes smaller than the rate for the first picture.
1. A video signal coding apparatus which codes a video signal including a luminance signal and a chrominance signal, and outputs a coded signal, the video signal coding apparatus comprising:
a coding unit configured to perform coding of at least quantization on a picture included in the video signal, and an output of the coded signal;
a code amount obtainment unit configured to obtain a luminance code amount and a chrominance code amount which are two code amounts included in the coded signal output from the coding unit, the luminance code amount being a code amount related to the luminance signal, and the chrominance code amount being a code amount related to the chrominance signal;
a calculation unit configured to compare the luminance code amount with the chrominance code amount obtained by the code amount obtainment unit based on a ratio of the chrominance code amount to the luminance code amount; and
a rate control unit configured to change, based on a result of the comparison by the calculation unit, a coefficient value of at least one of a first quantization matrix for the luminance signal and a second quantization matrix for the chrominance signal which are to be used in the quantization by the coding unit.
2. The video signal coding apparatus according to claim 1 ,
wherein the rate control unit is configured to increase the coefficient value of the first quantization matrix for the luminance signal, when it is judged from the result of the comparison by the calculation unit that the luminance code amount is prioritized in the comparison with the chrominance code amount.
3. The video signal coding apparatus according to claim 2 ,
wherein the rate control unit is further configured to increase the coefficient value of the second quantization matrix for the chrominance signal, when it is judged from the result of the comparison by the calculation unit that the chrominance code amount is prioritized in the comparison with the luminance code amount.
4. The video signal coding apparatus according to claim 1 ,
wherein the rate control unit is configured to decrease the coefficient value of the second quantization matrix for the chrominance signal, when it is judged from the result of the comparison by the calculation unit that the luminance code amount is prioritized in the comparison with the chrominance code amount.
5. A video signal coding method which codes a video signal including a luminance signal and a chrominance signal, and outputs a coded signal, the video signal coding method comprising:
a coding step of coding of at least quantization on a picture included in the video signal, and an outputting of the coded signal;
a code amount obtainment step of obtaining a luminance code amount and a chrominance code amount which are two code amounts included in the coded signal output from the coding step, the luminance code amount being a code amount related to the luminance signal, and the chrominance code amount being a code amount related to the chrominance signal;
a calculation step of comparing the luminance code amount with the chrominance code amount obtained by the code amount obtainment step based on a ratio of the chrominance code amount to the luminance code amount; and
a rate control step of changing, based on a result of the comparison by the calculation step, a coefficient value of at least one of a first quantization matrix for the luminance signal and a second quantization matrix for the chrominance signal which are to be used in the quantization by the coding step.
6. An integrated circuit which codes a video signal including a luminance signal and a chrominance signal, and outputs a coded signal, the integrating circuit comprising:
a coding unit configured to perform coding of at least quantization on a picture included in the video signal, and an output of the coded signal;
a code amount obtainment unit configured to obtain a luminance code amount and a chrominance code amount which are two code amounts included in the coded signal output from the coding unit, the luminance code amount being a code amount related to the luminance signal, and the chrominance code amount being a code amount related to the chrominance signal;
a calculation unit configured to compare the luminance code amount with the chrominance code amount obtained by the code amount obtainment unit based on a ratio of the chrominance code amount to the luminance code amount; and
a rate control unit configured to change, based on a result of the comparison by the calculation unit, a coefficient value of at least one of a first quantization matrix for the luminance signal and a second quantization matrix for the chrominance signal which are to be used in the quantization by the coding unit.