Enrico Baccaglini

Slice Sorting for Unequal Loss Protection of Video Streams

In this letter, we propose a novel unequal loss protection scheme, which allocates FEC codes to video slices according to their impact on the GOP distortion. This is evaluated taking the concealment procedure and the drift effect into account. Simulation results show that the proposed algorithm outperforms state-of-the-art approaches, reducing the gap with the error-free performance curve. Moreover, the complexity of the additional stage required to pilot the protection allocation stage is negligible with respect to traditional ULP schemes.

Unequal Protection of Video Data According to Slice Relevance

In this paper, we devise a procedure that mimics the behavior of a progressive video stream starting from a non progressive one such as H.264/AVC encoded video. This allows one to unequally protect the video data in an efficient way, according to their importance and the network state. The reported results demonstrate the superior performance of the proposed approach in comparison to state-of-the-art methods for resilient transmission of H.264/AVC data. Moreover, the flexibility in terms of redundancy insertion and achieved quality levels, allows one to span different applications, possibly including P2P video streaming.

A Flexible R-D-Based Multiple Description Scheme for JPEG 2000

Multiple description coding (MDC) is a good way to combat packet losses in error-prone networks subject to packet erasures. However, redundancy tuning is often difficult, and this makes the generation of descriptions with good redundancy-rate-distortion performance a hard job. Moreover, the complexity of generating more than two descriptions represents a strong limitation to MDC. In this letter, we propose a method that exploits the data rate-distortion characteristics to generate multiple descriptions for JPEG 2000 with tunable redundancy levels. The identification of the best number of descriptions as a function of the network conditions is also addressed

Multiple Descriptions Based on Multirate Coding for JPEG 2000 and H.264/AVC

Multiple description coding (MDC) makes use of redundant representations of multimedia data to achieve resiliency. Descriptions should be generated so that the quality obtained when decoding a subset of them only depends on their number and not on the particular received subset. In this paper, we propose a method based on the principle of encoding the source at several rates, and properly blending the data encoded at different rates to generate the descriptions. The aim is to achieve efficient redundancy exploitation, and easy adaptation to different network scenarios by means of fine tuning of the encoder parameters. We apply this principle to both JPEG 2000 images and H.264/AVC video data. We consider as the reference scenario the distribution of contents on application-layer overlays with multiple-tree topology. The experimental results reveal that our method favorably compares with state-of-art MDC techniques.

A Flexible Multi-Rate Allocation Scheme for Balanced Multiple Description Coding Applications

When transmitting multimedia information over non-prioritized networks subject to packet losses, multiple description coding with an arbitrary number of descriptions is an effective choice in order to minimize the end-to-end distortion. Such descriptions should be generated so that the quality obtained decoding a subset of them depends only on their number and not on the particular received subset. In this paper, we propose an encoding procedure to generate an arbitrary number of balanced descriptions using a multi-rate allocation scheme which exploits the R-D characteristic of the data

Image and video transmission: a comparison study of using unequal loss protection and multiple description coding

We present a performance comparison between multiple description coding (MDC) and unequal loss protection (ULP) as tools to deliver multimedia data to mobile users. Graceful-degradation encoding schemes are able to cope with packet losses due to time-variant channels as they allow the receivers to partially reconstruct the transmitted data with only a subset of received packets. We address a rate-distortion-based multiple description coding scheme and a state-of-the-art unequal loss protection algorithm based on Reed Solomon Forward Error Correction (FEC) codes. The comparison is performed using as a case study JPEG 2000 coded images and H.264/AVC video sequences transmitted over lossy packet networks. Complexity aspects are also considered. The simulation results show that both schemes allocate the same amount of redundancy for any given encoding output rate to protect the transmitted information. The main findings are that MDC, besides being computationally less intensive, achieves a smoother performance degradation, whereas, the ULP scheme yields superior performance in terms of the expected PSNR.

Network adaptive multiple description coding for JPEG2000

Despite multiple description coding (MDC) paradigm is effective to combat packet losses on networks, it is not included in any multimedia co-decoding standard. This can be justified by the complexity of the redundancy tuning task of many of the proposed methods. Moreover, the complexity of generating more than two descriptions represents a strong limitation to MDC. In this paper, we generalize the MDC scheme proposed for JPEG 2000 in T. Tillo and G. Olmo (2004) to more than two descriptions. Using this flexible MDC scheme, we show the importance of properly tuning both the redundancy and the number of descriptions to match the network condition. Finally, we derive the conditions in order to determine when it is better to use single description coding or MDC

Sensor aided H.264 Video Encoder for UAV applications

This paper presents a new low-complexity H.264 encoder for Unmanned Aerial Vehicles (UAV) applications. Standard video coding systems currently employed in UAV applications do not rely on some peculiarities in terms of scene 3D model and correlation among successive frames. In particular, the observed scene is static, i.e. the camera movement is dominant, and it can often be well approximated with a plane. Moreover, camera position and orientation can be obtained from the navigation system. Therefore, correspondent points on two video frames are linked by a simple homography. The encoder employs a new motion estimation scheme which make use of the global motion information provided by the onboard navigation system. The homography is used in order to initialize the block matching algorithm allowing a more robust motion estimation and a smaller search window, and hence reducing the complexity. Experimental results show that the proposed scheme ouperforms standard H.264 in terms of PSNR and throughput. The results are relevant in low frame rate video coding, which is a typical scenario in UAV behind line-of-sight (BLOS) missions. Experiments open new drections in developing new sensor aided video coding standards.

A study of an hybrid CDN-P2P system over the PlanetLab network

In this work we propose an hybrid CDN-P2P architecture for video contents delivery based on the NextShare platform. Experiments were conducted over the PlanetLab network using a number of peers which encompass real network behaviors. Results show that although the NextShare is based on the original BitTorrent file sharing mechanism, the implemented tools can efficiently deliver video over a heterogeneous and time varying network if peers can rely on an intermediate distribution layer between the CDN and the final users. Among the other benefits, CDN edge servers are significantly offloaded and peers can experience low start-up delays. Architecture design and simulation results are taking place in the context of the European FP7 project COAST.

Slice-level rate-distortion optimized multiple description coding for H.264/AVC

We propose a novel standard-compliant multiple description coding (MDC) method that exploits the H.264/AVC redundant slice tool, performing rate-distortion optimization at the slice level. The strategy to allocate redundancy to each slice jointly takes into account its contribution to distortion, its position in the GOP, the effect of decoder error concealment, and the transmission conditions. This makes the algorithm more accurate with respect to previous frame-based solutions, and experimental results show that it compares favorably with other state-of-the-art standard-compliant MDC techniques.