Patent ID: 8085854

Claim:
A decoder that decodes received macroblocks in a bitstream, a respective macroblock comprising up to four luminance blocks, the decoder comprising: a first module controlling a processor to determine a quantization parameter from quantization data in the bitstream; a second module controlling the processor to generate a luminance scalar according to a first piece-wise linear transformation of the quantization parameter, wherein: (i) the luminance scalar equals 8 whenever the quantization parameter falls within the values 1 through 4, inclusive; (ii) the luminance scalar equals 2 times the quantization parameter whenever the quantization parameter falls within the values 5 through 8, inclusive; (iii) the luminance scalar equals the quantization parameter plus 8 whenever the quantization parameter falls within the values 9 through 24, inclusive; and (iv) the luminance scalar equals 2 times the quantization parameter; a third module controlling the processor to inverse quantize a DC coefficient of a respective luminance block of the up to four luminance blocks by the luminance scalar to yield a respective inverse quantized DC coefficient; a fourth module controlling the processor to transform data of the up to four luminance blocks, including the respective inverse quantized DC coefficient, according to an inverse discrete cosine transform; and a fifth module controlling the processor to merge data of the up to four luminance blocks to generate image data associated with the respective macroblock.