TRANSCODING BETWEEN DIFFERENT DCT-BASED IMAGE COMPRESSION STANDARDS

摘要

An input encoded video bitstream conforming to a first DCT-based image compression standard (e.g., MJPEG or DV) is converted into an output encoded video bitstream conforming to a second DCT-based image compression standard (e.g., MPEG) without having to fully decode the first bitstream according to the first image compression standard and without having to fully encode according to the second image compression standard in order to generate the output bitstream. Rather, a partial video decoder of a transcoding system applies steps of the first image compression standard to the input bitstream to generate dequantized DCT coefficient data. A DCT data converter of the transcoding system then processes the dequantized DCT coefficient data in the DCT domain as necessary to enable a partial video encoder of the transcoding system to apply steps of the second image compression standard to the converted DCT coefficient data in order to generate the output bitstream.