New DCT-domain transcoding using split and merge technique

For the conventional downscaling video transcoder. the video server would be to first decompress the video, perform the downscaling operation in the pixel domain. and then recompress it. This is computational intensive. However, i t is difiieult to perfonn video downscaling i n the DCT-donlain since the prediction errors of each frame are computed from its immediate past higher resolution frames. Besides, the motion vector need to resainple due to the size of the video is changed. Due to the mismatch of the resampled motion vector s’ith the incoming E T coeficients, the video transcoder need to recalculate the ncw DCT coetficient with lower resolution in pixel domaiir, this can create undesirable cotnplexity as well as introduce re-encoding error. In this paper, we propose a new’ architecture to obtain the new DCT coetlicients and the new motion \lector by reuse the incoming motion vector and DCT coefficients. Since our proposed transcoder is mainly pcrfarming in DCT domain. IOW computational complexity can he achieved as well as the re-encoding can he reduced. Experimental result show, that our proposed video downscaling transcoder can lead to significant computational savings as well as provide a high video quality compared to the conventional approach.