Method and apparatus for transcoding bit streams with video data

US6081295A · kind A · utility

Assignee

• Deutsche Thomson-Brandt GmbH · DE

Inventors

• Dirk Adolph · Ronnenberg, DE
• Dietrich Westerkamp · Hannover, DE
• Carsten Herpel · Bad Driburg, DE
• Ingo Hütter · Celle, DE

Key dates

• Filing date: Apr 21, 1995
• Grant date: Jun 27, 2000
• Expiry date: Apr 21, 2015

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04N19/40
• WIPO field: Audio-visual technology
• WIPO sector: Electrical engineering

Abstract

The coding or decoding of video data with the associated audio and/or other data can be performed, for example, on the basis of the standards ISO/IEC 11172 (MPEG1) or ISO/IEC 13818 (MPEG2). Such coding and decoding can include the conversion of a primary bit stream coded on the basis of such standards into a secondary bit stream with a different data rate. Since the information content of the motion vectors from the primary bit stream retain their validity in the secondary bit stream, it is not necessary to recalculate motion vectors for transcoding. Instead, encoding of the secondary bit stream is performed with the aid of the motion vectors from the primary bit stream which are reused. In such a case, the encoding of the secondary bit stream is carried out in a restricted prediction mode, i.e. only those prediction modes which are described by respective block type or the motion information of the primary bit stream are allowed in the secondary bit stream.