Embedded indexing in scalable video coding

Effective encoding and indexing of audiovisual documents are two key aspects for enhancing the multimedia user experience. In this paper we propose the embedding of low-level content descriptors into a scalable video-coding bitstream by jointly optimizing encoding and indexing performance. This approach provides a new type of bitstream where part of the information is used for both content encoding and content description, allowing the so called "Midstream Content Access". To support this concept, a novel technique based on the appropriate combination of Vector Quantization and Scalable Video Coding has been developed and evaluated. More specifically, the key-pictures of each video Group Of Pictures (GOP) are encoded at a first draft level by using a suitable visual-codebook, while the residual errors are encoded using a conventional approach. The same visual-codebook is also used to encode all the key-pictures of a video shot, where boundaries are dynamically estimated. In this way, the visual-codebook is freely available as an efficient visual descriptor of the considered video shot. Moreover, since a new visual-codebook is introduced every time a new shot is detected, also an implicit temporal segmentation is provided.