| 摘要 |
A coding apparatus that codes video data using an arithmetic coding scheme such as the AVC standard includes an orthogonal transformation unit, a quantizer, an arithmetic coder, and a controller. The arithmetic coder includes a binarization unit, a binary arithmetic coder, and a code length predictor. The code length predictor outputs a predicted number of bits by evaluating a predictive function using, as the argument of the function, the bin size of the binary symbols generated from input data during coding. The controller controls the coding bit rate by changing the quantization scale of the quantizer on the basis of the predicted number of bits. The predictive function is defined such that the predicted number of bits increases as the bin size increases, and furthermore such that the polynomial degree of the function changes when the bin size exceeds a predefined threshold value.
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