Abstract: Methods and transcoders are disclosed for video transcoding input macroblocks to an output macroblock. One of the methods estimates an output macroblock mode for the video transcoding. A spatial weight is determined based on size of overlapping areas of each of the input macroblocks with a correlation area that is correlated with the output macroblock. A discrete cosine transform (DCT) weight is determined based on a number of zero DCT coefficients of each of the input macroblocks that overlap the correlation area. The output macroblock mode is estimated based on the spatial weight and the DCT weight.

Abstract: A method of estimating output motion vector includes generating a group of candidate motion vectors, selecting two or more reference vectors, variably establishing a search window, and estimating an output motion vector by performing a motion vector refinement on the search window. The method selects the two or more reference vectors from the group of the candidate motion vectors and the search window is established according to a relativity among the reference vectors. A transcoder using the method includes an encoding parameter estimator configured to select the two or more reference vectors and to variably establish the search window according to the relativity between the reference vectors. Therefore, the search window may be efficiently established without increasing calculation time, so that the output motion vector may be more correctly estimated.

Abstract: A method of estimating output motion vector includes generating a group of candidate motion vectors, selecting two or more reference vectors, variably establishing a search window, and estimating an output motion vector by performing a motion vector refinement on the search window. The method selects the two or more reference vectors from the group of the candidate motion vectors and the search window is established according to a relativity among the reference vectors. A transcoder using the method includes an encoding parameter estimator configured to select the two or more reference vectors and to variably establish the search window according to the relativity between the reference vectors. Therefore, the search window may be efficiently established without increasing calculation time, so that the output motion vector may be more correctly estimated.

Abstract: Methods and transcoders are disclosed for video transcoding input macroblocks to an output macroblock. One of the methods estimates an output macroblock mode for the video transcoding. A spatial weight is determined based on size of overlapping areas of each of the input macroblocks with a correlation area that is correlated with the output macroblock. A discrete cosine transform (DCT) weight is determined based on a number of zero DCT coefficients of each of the input macroblocks that overlap the correlation area. The output macroblock mode is estimated based on the spatial weight and the DCT weight.