Patent ID: 7924919
Filing Date: 2011-04-12
Classification: H04N

Abstract:
1. A transcoder for decoding a motion picture stream encoded by using a first coding scheme, which provides intraframe coding and interframe predictive coding, and encoding the decoded motion picture stream by using a second coding scheme, the transcoder comprising: a decoder for decoding an input motion picture stream and detecting sub-information indicating whether an intraframe coding scheme or an interframe predictive coding scheme is used, wherein the sub-information is attached to each decoding process unit within a frame; and an encoder for changing the frame to be referenced at the time of coding depending on whether the sub-information indicates the use of the intraframe coding scheme or the interframe predictive coding scheme, wherein a reference frame for motion compensation can be selected from a plurality of decoded frames in units of an encoding process unit in the second coding scheme, when a frame to be encoded in the second coding scheme used the interframe predictive coding scheme in the first coding scheme and the sub-information attached to encoding process unit within the frame to be encoded indicates the use of the intraframe coding scheme, a decoded frame which was not referenced in the first coding scheme is selected as a reference frame for the encoding process unit in the second coding scheme.