Fabrizio Rovati

Frame concealment for H.264/AVC decoders

The H.264/AVC offers a high video coding efficiency and is the first standard that provides an explicit support for the transmission of multimedia content over a packed switched network, specifying a network abstraction layer (NAL). If we consider the transmission of a low resolution video sequence over a wireless LAN network or a UMTS link, we can usually observe that a coded picture typically fits the packet size, therefore a transmission error produces the loss of a whole frame. In this paper, we propose a novel technique to perform the concealment of a whole frame for H.264/A VC video decoders.

Scalable Video Coding for IPTV Services

Scenarios for the use of the recently approved scalable video coding (SVC) extension of H.264/MPEG4-AVC in IPTV services are presented. For that, a brief technical overview of SVC when deployed in IPTV services is provided. The coding efficiency of the various scalability types of SVC is demonstrated followed by an analysis of the complexity of the various SVC tools. Based on this technical characterization, it is described how the different SVC features such as efficient methods for graceful degradation, bit rate adaptation, and format adaptation, can be mapped to application requirements of IPTV services. It is discussed how such mappings can lead to improved content portability, management and distribution as well as an improved management of access network throughput resulting in better quality of service and experience for the users of IPTV services.

Dynamic control of motion estimation search parameters for low complex H.264/AVC video coding

This paper presents a novel technique to reduce the motion estimation (ME) complexity in H.264/AVC video coding. A low complexity context-aware controller is added to a basic search engine; at coding time the controller extracts from the search engine partial results information on the input signal statistics, using them to dynamically configure the ME search parameters, such as number of reference frames, valid block modes and search area. Unnecessary computations and memory accesses can be avoided, decreasing ME complexity while keeping unaltered coding efficiency for a wide range of applications: bit-rates from tens of kbits/s to tens of Mbits/s and video formats from QCIF to CCIR. The context-aware control can be used with any ME search engine and in the paper is successfully applied to full search and fast ME, as EPZS and UMHS, in the JM10 software model of H264/AVC

Peer-to-peer streaming of scalable video in future Internet applications

Scalable video delivery over peer-to-peer networks appears to be key for efficient streaming in emerging and future Internet applications. Contrasting the conventional server-client approach, here, video is delivered to a user in a fully distributed fashion. This is, for instance, beneficial in cases where a high demand for a particular video content is imposed, as different users can receive the same data from different peers. Furthermore, due to the heterogeneous nature of Internet connectivity, the content needs to be delivered to a user through networks with highly varying bandwidths. Moreover, content needs to be displayed on a variety of devices featuring different sizes, resolutions, and computational capabilities. If video is encoded in a scalable way, it can be adapted to any required spatio-temporal resolution and quality in the compressed domain, according to a peer bandwidth and other peers¿ context requirements. This enables efficient low-complexity content adaptation and interoperability for improved peer-to-peer streaming in future Internet applications. An efficient piece picking and peer selection policy enables high quality of service in such a streaming system.

An innovative, high quality and search window independent motion estimation algorithm and architecture for MPEG-2 encoding

This paper describes an innovative, pipelined, cache-based architecture for a motion estimation coprocessor. The coprocessor is based on a predictive/recursive algorithm whose computational complexity is low and not dependent on the search window. The synergies between the architecture and algorithms features allow a high picture quality, low-area, low-bandwidth, unlimited search window implementation.

Performance analysis of the scalable video coding standard

The emerging Scalable Video Coding extends the H.264/AVC video coding standard with new tools designed to efficiently support temporal, spatial and SNR scalability. This paper gives a comprehensive overview of the new features of the SVC standard, providing at the same time an evaluation of their Rate-Distortion performance as well as of the computational complexity.

Low-complexity standard-compatible robust and scalable video streaming over lossy/variable bandwidth networks

We propose a robust and scalable transmission scheme based on multiple description coding (MDC). Each description is encoded using a standard video codec such as MPEG-2 or H.264. This scheme provides equal or better robustness with respect to other solutions such as forward error correction (FEC), at lower system complexity; also, it provides scalability by selectively dropping descriptions.

An innovative, programmable architecture for ultra-low power motion estimation in reduced memory MPEG-4 encoder

This paper describes an ultra-low power, cache based, and programmable motion estimator with memory reduction for MPEG-4 video encoding. It exploits a low complexity motion estimation algorithm, achieving a quality comparable to the full search approach with only 1% of the computation and the power consumption.

Wireless adaptive video streaming by real-time channel estimation and video transcoding

A system composed of an MPEG-2 video transcoder to change bitrate, frame rate and frame size and a cross layer controller gathering information from physical, MAC, driver, and RTCP layers, calculating instantaneous network throughput, to optimize real-time adaptive A/V streaming over IEEE 802.11 is presented.

An interoperable multimedia delivery framework for scalable video coding based on MPEG-21 Digital Item Adaptation

In this paper we present an interoperable multimedia delivery framework for scalable video coding based on MPEG-21 digital item adaptation (DIA). In can be used to transmit scalable video contents within heterogeneous usage environments where the properties of the usage environment (e.g., terminal/network capabilities) may change dynamically during the streaming session. The usage environment is signaled by interoperable description formats provided by the DIA standard. Additionally, the adaptation itself is done by exploiting the standardpsilas generic adaptation approach, i.e., independent of the actual coding format. Thus, the overall framework is also applicable for other scalable coding formats.