Encoder and Decoder Side Global and Local Motion Estimation for Distributed Video Coding

International audienceIn this paper, we propose a new Distributed Video Coding (DVC) architecture where motion estimation is performed both at the encoder and decoder, effectively combining global and local motion models. We show that the proposed approach improves significantly the quality of Side Information (SI), especially for sequences with complex motion patterns. In turn, it leads to rate-distortion gains of up to 1 dB when compared to the state-of-the-art DISCOVER DVC codec

GLOBAL MOTION GUIDED ADAPTIVE TEMPORAL INTER- / EXTRAPOLATION FOR SIDE INFORMATION GENERATION IN DISTRIBUTED VIDEO CODING

The ongoing research on Distributed Video Coding (DVC) is focused on flexibility and increased rate distortion (RD) performance. Besides Slepian-Wolf (SW) coding and coder control, a good side information (SI) quality is essential for high RD performance. The SI is typically extracted by temporal inter-/extrapolation. Fast motion is still a challenge. Two global motion guided adaptive temporal inter-/extrapolation (GTIE/GpTIE) schemes are proposed. They incorporate fast camera motion by global motion estimation and subsequent refinement. The issue of occlusion and revelation at the frame border is solved by an adaptive temporal inter-/extrapolation method. Simulation results show an RD performance increase of up to 3.1 dB

Fusion of Global and Local Motion Estimation Using Foreground Objects for Distributed Video Coding

International audienceThe side information in distributed video coding is estimated using the available decoded frames, and exploited for the decoding and reconstruction of other frames. The quality of the side information has a strong impact on the performance of distributed video coding. Here we propose a new approach that combines both global and local side information to improve coding performance. Since the background pixels in a frame are assigned to global estimation and the foreground objects to local estimation, one needs to estimate foreground objects in the side information using the backward and forward foreground objects, The background pixels are directly taken from the global side information. Specifically, elastic curves and local motion compensation are used to generate the foreground objects masks in the side information. Experimental results show that, as far as the rate-distortion performance is concerned, the proposed approach can achieve a PSNR improvement of up to 1.39 dB for a GOP size of 2, and up to 4.73 dB for larger GOP sizes, with respect to the reference DISCOVER codec. Index Terms A. ABOU-ELAILAH, F. DUFAUX, M. CAGNAZZO, and B. PESQUET-POPESCU are with the Signal and Image Processin

Distributed video coding with feedback channel constraints

Many of the distributed video coding (DVC) systems described in the literature make use of a feedback channel from the decoder to the encoder to determine the rate. However, the number of requests through the feedback channel is often high, and as a result the overall delay of the system could be unacceptable in practical applications. As a solution, feedback-free DVC systems have been proposed, but the problem with these solutions is that they incorporate a difficult trade-off between encoder complexity and compression performance. Recognizing that a limited form of feedback may be supported in many video-streaming scenarios, in this paper we propose a method for constraining the number of feedback requests to a fixed maximum number of N requests for an entire Wyner-Ziv (WZ) frame. The proposed technique estimates the WZ rate at the decoder using information obtained from previously decoded WZ frames and defines the N requests by minimizing the expected rate overhead. Tests on eight sequences show that the rate penalty is less than 5% when only five requests are allowed per WZ frame (for a group of pictures of size four). Furthermore, due to improvements from previous work, the system is able to perform better than or similar to DISCOVER even when up to two requests per WZ frame are allowed. The practical usefulness of the proposed approach is studied by estimating end-to-end delay and encoder buffer requirements, indicating that DVC with constrained feedback can be an important solution in the context of video-streaming scenarios

Ein Beitrag zur Pixel-basierten Verteilten Videocodierung: Seiteninformationsgenerierung, WZ-Codierung und flexible Decodierung

Moderne Anwendungsszenarien, wie die individuelle Übertragung von Videodaten zwischen mobilen Endgeräten, stellen neue Herausforderungen an das Videoübertragungssystem. Hierbei liegt ein besonderer Fokus auf der geringen Komplexität des Videoencoders. Diese Anforderung kann mit Hilfe der Verteilten Videocodierung erfüllt werden. Im Fokus der vorliegenden Arbeit liegen die sehr geringe Encoderkomplexität sowie auch die Steigerung der Leistungsfähigkeit und die Verbesserung der Flexibilität des Decodierungsprozesses. Einer der wesentlichen Beiträge der Arbeit bezieht sich auf die Verbesserung der Seiteninformationsqualität durch temporale Interpolation

Towards Computational Efficiency of Next Generation Multimedia Systems

To address throughput demands of complex applications (like Multimedia), a next-generation system designer needs to co-design and co-optimize the hardware and software layers. Hardware/software knobs must be tuned in synergy to increase the throughput efficiency. This thesis provides such algorithmic and architectural solutions, while considering the new technology challenges (power-cap and memory aging). The goal is to maximize the throughput efficiency, under timing- and hardware-constraints