Transcoding of MPEG video using lattice vector quantization

We propose a new transcoding method for MPEG video bit-streams. In our implementation, instead of using scalar quantization in the transcoder, a lattice vector quantizer (LVQ) is applied to exceed the MPEG compression capabilities while providing acceptable quality. In this way, the transcoded video is not MPEG-compatible anymore, hence a low cost user interface is needed prior to the MPEG decoding. However, the decoded pictures have higher subjective quality compared to those transcoded by an MPEG-compatible transcoder at the same bit-rate. Due to the LVQ the quantization noise is more uniform on the pictures, and less artifacts are visible around the edges. Beside this, a slight improvement in the PSNR was also experienced by using certain LVQ parameters.