| 摘要 |
A layered audiovisual packet data stream (CNT'), such as one obtained by a JPEG2000 encoder (810), is received together with information (metadata) about the contribution of each packet to the reduction of image distortion. The distortion-to-rate ratio for each packet is calculated (710) and the packets are ordered (720) is descending ratio. The non-encrypted packet having the highest ratio is encrypted (730) until the target distortion is obtained. Also provided is an apparatus (800). In a variant, the data in the packets are substituted by dummy data instead of encrypted. |
