31.8.1 mips_h264_iqt

Description

Combined inverse quantization and inverse transform function. The input DCT coefficients are inverse quantized by multiplying them with corresponding elements of the inverse quantization matrix. The results are transformed by a 4x4¦-element integer inverse DCT as specified in the H.264 video compression standard.

Include

dsplib_video.h

Prototype

void
mips_h264_iqt
(
       uint8 b[4][4],
       int16 c[4][4],
       int16 iq[4][4]
);

Argument

b: Output 4x4-pixel array in 8-bit unsigned integer format.

c: Input 4x4-element array of DCT coefficients in signed 16-bit integer format.

iq: Inverse quantization matrix in signed 16-bit integer format.

Return Value

None.

Remarks

The pointers b, c, and iq must be aligned on 4-byte boundaries.

Notes

The mips_iqt_setup() function can be used to initialize the iq array.

Example:

uint8 b[4][4]
int16 dct_data[4][4];
int16 iq_matrix[4][4];

// quantization parameter
int QP = 28;

// initialize the inverse quantization matrix
mips_h264_iqt_setup(iq_matrix, mips_h264_iq_coeffs, QP);

...

// load DCT data into dct_data
   ...

mips_h264_iqt(b, dct_data, iq_matrix);