Treffer: Distributed and compressed multimedia transmission using a discrete backprojection operator

To meet QoS for multimedia transmission over packet-lossy network such as IP networks, two ways can be followed, either the source scalability is extended to packets, or multiple description schemes are used. In this case, equivalence between packets is assumed and forward error correction is needed. In this paper the proposed solution allows multiple description of a scalable bitstream source using a backprojection operator. This operator belongs to the class of the Mojette transforms, already presented in ITCom2001. In this scheme a redundant projections set is firstly computed for different angles. In a second step only few projections are selected to check the reconstructibility (quantization step). Third an entropic coding on remaining projections is applied. The Mojette transform is an exact discrete Radon transform generating bins from ixels (information elements) computed as XOR or standard additions. This transform is linear (in number of ixels and number of projections) both for coding and decoding. In this new scheme we propose, sub flows (when assuming source scalability) issued from the application output bitstreams are mapped into buffers. The projections issued from these buffers meet both the compression of the bitstreams and the multiple descriptions constraints.