A new class of codes for robust compression of heterogeneous data: Multiplexed Codes
نویسندگان
چکیده
Compression systems of real signals (images, video, audio) generate sources of information with diierent levels of priority which are then encoded with variable length codes (VLC). This paper addresses the issue of robust transmission of such VLC encoded heterogeneous sources over error-prone channels. VLCs are very sensitive to channel noise: when some bits are altered, synchronization losses can occur at the receiver. This paper describes a new family of codes, called multiplexed codes, that allow to connne the de-synchronization phenomenon to low priority data while allowing to reach asymptotically the entropy bound for both (low and high priority) sources. The idea consists in creating xed length codes for high priority information and in using the inherent redundancy to describe low priority data, hence the name multiplexed codes. Theoritical and simulation results reveal a very high error resilience at almost no cost in compression eeciency. Herv JJgou is with IRISA/ENS Cachan, Christine Guillemot is with IRISA/INRIA Une nouvelle classe de codes pour la compression robuste de donnnes hhttroggnes: les Codes Multiplexxs RRsumm : Les systtmes de compression de signaux rrels (images, viddo, son) produisent des sources d'informations de prioritts diiirentes, qui sont encoddes en utilisant des codes longueur variable (VLC). Cet article traite du probllme de la transmission de telles sources sur des canaux sujets erreurs. Les codes longueur variable sont trrs sensibles au bruit de transmission: lorsque des inversions de bits se produisent, la synchronisation est perdue au ddcodeur. Une nouvelle famille de codes, les codes multiplexxs, permettent de connner le phhnommne de ddsynchronisation des donnnes moins prioritaires, tout en permettant d'atteindre la borne entropique pour l'ensemble des donnnes. Le principe consiste crrer un code longueur xe pour la source de donnnes prioritaires et d'utiliser la redondance intrinssque de ce code pour ddcrire les donnnes moins prioritaires. Les rrsultats de simulations et thhoriques ddmontrent une rrsistance aux erreurs trrs importante pour une perte d'eecacitt en compression trrs faible.
منابع مشابه
Robust codes and joint source-channel codes for multimedia transmission over mobile channels. (Codes robustes et codes joints source-canal pour transmission multimédia sur canaux mobiles)
Compression systems of real signals (images, video, audio) generate sources of information with different levels of priority which are then encoded with variable length codes (VLC). This chapter addresses the issue of robust transmission of such VLC encoded heterogeneous sources over error-prone channels. VLCs are very sensitive to channel noise : when some bits are altered, synchronization los...
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