Transcoding system using encoding history information

摘要

The present invention provides a transcoder having a MPEG decoder and a MPEG encoder, for changing a GOP structure and the bit rate of an encoded bitstream obtained as a result of an encoding process. The MPEG encoder receives a past encoding parameters generated at a past encoding process as a history information, and performs a present encoding process by using the past encoding parameters selectively so that the present encoding process is optimized. Furthermore, the encoder describe the past encoding parameters into the encoded bitstream as the history information so as to reuse the history information in advance encoding process. The picture quality of the video data does not deteriorate even if decoding and encoding processes are carried out repeatedly by the transcoder.

主权项

1. Decoding apparatus for decoding an encoded stream, comprising:
receiving means for receiving the encoded stream, history encoding parameters utilized in past encoding processes for the encoded stream and current encoding parameters utilized upon production of the encoded stream, wherein the current encoding parameters correspond to a most recent encoding process and the history encoding parameters correspond to more than two different successively performed encoding processes prior to the encoding process of the current encoding parameters; decoding means for decoding the received encoded stream utilizing the received current encoding parameters to produce image data; and output means for outputting the history encoding parameters, the current encoding parameters, and the image data produced by said decoding means so that, when the image data produced by said decoding means is re-encoded by a succeeding encoder, the received history encoding parameters and current encoding parameters are utilized for re-encoding by the succeeding encoder, wherein the history encoding parameters and the current encoding parameters are included in the encoded stream, and said receiving means acquires the history encoding parameters and the current encoding parameters from the encoded stream.