Robust MAC-lite and soft header recovery for packetized multimedia transmission

Abstract

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Robust critical data recovery for MPEG-4 AAC encoded bitstreams

“…Data are segmented in transport-level frames, according to the network protocol [3]. It is assumed that, at the receiver side, reliability information at the output of the PHY layer reaches the APL layer and may be used by the source decoder [19,22]. This assumption is reasonable because all processing is performed inside the receiver terminal.…”

“…Taking into account the observations y, the knowledge of k, p, and , as well as the CRC properties, one may obtain the maximum a posteriori estimatê u = arg max u∈Ω (u|k, p, , y , y , y ) for u. After some derivations detailed in [22], one obtainŝ…”

“…This results in many cases to an unmanageable computational complexity. A trellis decoding inspired from [24] has been proposed in [22]. This techniques allows to reduce the evaluation of (2) to (2 ℓ ) operations.…”

Joint Exploitation of Residual Source Information and MAC Layer CRC Redundancy for Robust Video Decoding

“…These changes require some information to be available everywhere inside the receiver and are compatible with the usual transmission structure: only the receiver has to be modified, and both the transmitter operations and the signal sent are unchanged. As outlined above, they are facilitated by using the robust header recovery and permeable layer mechanisms presented in [10], [20]. Here, the headers are assumed to be available without errors at all layers.…”

“…Obviously, this does not correspond to a classical structure of the decoder, and requires the use of some additional tools, some of which being proposed elsewhere by the same authors. In particular, we proposed a header recovery technique exploiting the intra-layer and inter-layer redundancies along with the CRCs or checksums in [20]. With this technique, the header is very likely to be correctly decoded even for poor SNRs, and the payload may be forwarded to the upper layers, resulting in a permeable protocol stack.…”