| 摘要 |
An MPEG2 encoded signal comprising intra-encoded pictures I and inter-encoded pictures B is decoded (70-74) to baseband and re-encoded (76) to I-pictures. The quantisation levels Qv and the motion vectors Mv of the B pictures are retained unchanged and maintained in association with the corresponding pictures re-encoded as I-pictures. The I-pictures can be decoded to baseband, processed, and re-encoded as I-pictures without degradation. The I-pictures can then be re-encoded back to e.g. I, B pictures with minimal degradation. Alternatively, some of the I-pictures are decoded and converted to B pictures retaining unchanged the quantisation levels thereof. |
