Method and apparatus to encode a moving image with fixed computational complexity

An apparatus to encode a moving image, comprising:

• a discrete cosine transform (DCT) unit performing a DCT process on input video data on a block-by-block basis;
• a quantizer quantizing the input video data on which the DCT process is performed and generating a quantization parameter;
• a motion estimation (ME) unit calculating a motion vector and a sum of absolute difference (SAD) per macro block, using the input video data and video data of a previous frame;
• a DCT computational complexity calculator calculating a computational complexity of the ME unit, estimating a difference between the ME computational complexity and a target ME computational complexity, and updating a target DCT computational complexity based on the estimated difference;
• and
• a DCT skipping unit setting a threshold value to determine whether to skip performing the DCT process on the input video data, based on the target DCT computational complexity updated by the DCT computational complexity calculator, comparing the SAD per macro block and the quantization parameter with the threshold value, and determining whether to allow the DCT unit to perform the DCT process on the input video data.

An apparatus to encode a moving image, comprising:

• a DCT unit performing a DCT process on video data in an 8×8 block-by-block unit or processing the video data not to be coded;
• a motion estimation (ME) unit estimating a motion vector (MV) and a sum of absolute difference (SAD) per macro block using the video data of a current frame and the video data of a previous frame;
• a motion estimation (ME) computational complexity calculator averaging or adding search points per macro block to calculate an overall or total ME computational complexity S(n) of the current frame;
• and
• a target DCT computational complexity calculator comparing the overall ME computational complexity S(n) with a target ME computational complexity St, calculating a difference therebetween, and adding the difference to a target DCT computational complexity Ct to change the target DCT computational complexity Ct to obtain an updated DCT computational complexity C′t.

An apparatus to encode a moving image, comprising:

• a discrete cosine transform (DCT) skipping unit generating a DCT skipping control signal;
• a DCT unit performing a DCT process on video data in an 8×8 block-by-block unit or processing the video data not to be coded in response to the DCT skipping control signal;
• a motion estimation (ME) unit estimating a motion vector (MV) and a sum of absolute difference (SAD) per macro block using the video data of a current frame and the video data of a previous frame;
• and
• a DCT computational complexity calculator calculating an overall ME computational complexity of the previous frame to estimate a difference between the overall ME computational complexity and a target ME and applying the difference to the DCT skipping unit to maintain an amount of overall DCT computation close to a target DCT computational complexity.

A computer readable storage controlling a computer to estimate a motion of a moving image and comprising a process of encoding a moving image, comprising:

• calculating motion estimation (ME) computational complexity of video data, and estimating a difference between the calculated ME computational complexity and a target ME computational complexity;
• updating a target discrete cosine transform (DCT) complexity based on the difference between the calculated ME computational complexity and the target ME computational complexity;
• setting a threshold value in order to determine whether to skip performing a DCT process on the video data based on the updated target DCT complexity;
• and
• skip performing the DCT process or performing the DCT process on video data according to the set threshold value.