Patent ID: 8155195

Claim:
A method comprising, during motion estimation: determining a distortion metric selection criterion for motion estimation, wherein the distortion metric selection criterion is based at least in part on initial results of the motion estimation; determining a selection threshold that is based at least in part on a frequency transform to be used in subsequent encoding of motion-compensation residuals, wherein the selection threshold is set to a value below which the motion-compensation residuals will have no non-zero-value quantized frequency transform coefficients and above which the motion-compensation residuals may have non-zero-value quantized frequency transform coefficients; selecting a distortion metric based at least in part on the selection threshold and the distortion metric selection criterion, including choosing between plural available distortion metrics to trade off computational complexity, versus accuracy of approximation of rate-distortion cost, wherein the plural available distortion metrics include a sample-domain distortion metric and a transform-domain distortion metric, the sample-domain distortion metric being characterized by lower computational complexity but worse accuracy of approximation of rate-distortion cost, and the transform-domain distortion metric being characterized by better accuracy of approximation of rate-distortion cost but higher computational complexity, wherein the selecting includes comparing the distortion metric selection criterion to the selection threshold, wherein if the distortion metric selection criterion is below the selection threshold, then the sample-domain distortion metric is selected, and wherein if the distortion metric selection criterion is above the selection threshold, then the transform-domain distortion metric is selected; using the selected distortion metric in the motion estimation; and outputting final results of the motion estimation.