Unequal error protection of embedded multimedia objects for packet-erasure channels

Abstract

The application of forward-error-correcting codes to the data. The most straightforward approach to FEC protection data organized as multiple, independent multimedia objects and is that of equal loss protection (ELP) in which the strength of erencoded with modern embedded coders is investigated. Capital-ror protection is applied equally to all portions of the data to be izing on the strict importance-ordering characteristic of emhedded the strength of the proteetion is optimized transmitted. Alternatively, unequal-error-protection (UEP) alsuch that data that is more important to the reconstructed qual-gorithms assign unequal amounts OfFEC Protection to the data ity of the dataset is assigned stronger protection. The focus of the in an effort to vary protection strength according to the imporinvestigation is on providing this optimization while maintaining tance of portions of the data. When UEP FEC codes are the ability to independently access the individual multimedia oh-applied to data that has subjected to lossy compression, the jects. Experimental results are presented for still-image objects a in reconstruction quality, and that this cost increases as the UEP redundancy is usually the quality of the reconstruction. In channel-loss conditions actually experienced degrade from those general terms, the UEP approach tends to perform better than for which the optimal protection arrangement was designed.ELP in terms of quality, since one can better optimize the UEP placement so as to maximize the quality of the reconstruction of the data. UEP is particularly suited to embedded coding since that illustrate the desired independent-access ability comes at measure of "importance" in determining the application of the T T . r . , . -n n n . r r T r n n 1. I , Y '~V " " C I 1 V 1 * Multimedia scenes are commonly represented as compositions of multiple, distinct objects so as to permit access and manipulation of one object independently of others. For this reason, objects in a multimedia dataset are encoded independently along with information on size and position within the dataset, so that, at the decoder, users can both decode an object of interest and also interactively manipulate object composition without the need to decode the entire scene. The recent MPEG-4 standard relies heavily on object-based representation of scenes, and the standard includes definitions for arbitrarily shaped video objects and arbitrarily shaped still-image texture .. .the coded bitstream in this case is arranged in order of decreasing importance during the encoding process. The work presented here investigates the FEC protection of object-based embedded coding. Specifically, we explore the assignment of UEP to objects of a multimedia dataset with the goals that each object 1) is protected within itself according to the importance of each of its bits to the reconstruction quality of the object, 2) has an object-level amount of error protection proportional to the object's importance to the reconstruction quality of the scene, and 3) can be ...

Proactive Retransmission and Buffer Management for Layered Video Transmission over Wireless Channel

“…This is because the amount of data FEC can recover is pre-determined with the estimate of the packet loss probability. The unequal error protection scheme [3], [5], [7] dynamically determines FEC redundancy according to the importance of bits or frames, however, this scheme cannot adapt FEC redundancy to ongoing loss process.…”