Daniele Alfonso

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

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.

Adaptive gop size control in h.264/avc encoding based on scene change detection

An efficient method is proposed to dynamically adapt the group of pictures (GOP) size in H.264/AVC encoding, by on-the-fly identification of scene changes in the input video signal. Intra coding picture decision is taken at the end of the pre-analysis phase of a fast motion estimation method based on spatial-temporal motion correlation. With negligible additional computation and memory requirements, the proposed method allows improving the compression of the whole coding process by up to 15%, without affecting the overall image quality

Bi-directionady motion-compensated frame-rate up-conversion for H.264/AVC decoders

We propose a technique to perform frame-rate up-conversion in baseline H.264/AVC compliant decoders. It exploits a low-complexity motion estimation algorithm including a novel method to enhance the consistency of motion fields. The final interpolation through adaptive median filtering provides excellent results in terms of objective and subjective visual quality

Detailed rate-distortion analysis of H.264 video coding standard and comparison to MPEG2/4

H.264 is an emerging video coding standard, providing significant improvements with respect to its ancestors, like MPEG-2 and MPEG-4. In this paper, we present an evaluation of the most important H.264 coding tools in terms of visual quality and compression efficiency

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.

Optimal rate adaptation with Integer Linear Programming in the scalable extension of H.264/AVC

Adaptation for scalable video is one of the recent challenges in video distribution over modern networks, which are heterogeneous both in terms of available bandwidth and user end terminal capability. Scalable Video Coding offers the possibility to adapt the content following the “quality layer” abstraction. In this work we present a new method to optimally define quality layers using Integer Linear Programming and distortion models. The performances of the proposed approach are comparable with the state-of-the-art methods, but they are obtained with strong complexity reduction and augmented flexibility.

Fast rate-distortion optimization in the H.264/AVC standard

Rate-Distortion Optimization (RDO) is a new feature of JVT H.264/AVC video encoder that enables a substantial enhanced efficiency with respect to all previous video coding standards. However, RDO causes a considerable increase in encoding computational complexity, proportional to the square of the search window size when the Full-Search motion estimation algorithm is applied. In this paper, a fast block-based predictive-recursive motion estimation algorithm is illustrated in combination with RDO algorithms. Extensive simulations show that, using the proposed algorithms, the time devoted to RDO is significantly reduced while keeping performance extremely close to JVT reference software JM8.6.

Hardware architecture for real time H.264 CABAC decoding for HDTV applications

H.264 or AVC (Advanced Video Coding) is a latest digital video codec standard which was developed as an answer to the growing demand for better compression in a wide range of applications and for improved network friendliness. H.264 is able to deliver a compression efficiency of up to 50% over a wide range of bit rates and video resolutions compared to previous standards (e.g. MPEG2 or H.263). The downside is that the H.264 decoder complexity is nearly four times higher than the previous standards. Hence a powerful hardware platform is required to provide real-time performance of H.264 in todays high-end applications like HDTV. We present an innovative Hardware architecture to perform real-time H.264 CABAC decoding using Finite State Machines (FSMs) for decoding of syntax elements. This architecture delivers a throughput of 1 bin per cycle @ 180MHz as reported by Synopsys Design Compiler.

Multiple description for robust Scalable Video Coding

Scalable Video Coding (SVC) was recently standardized as an extension of the H.264/AVC standard. A scalable coder allows to combine different layers of spatial, temporal and quality scalability, and is a viable solution for adaptation to user characteristics and network conditions. On the other hand, Multiple description coding (MDC) can provide error resilience and graceful quality degradation for transmission over error-prone channels. In this paper, we propose a video codec that combines the SVC and MDC coding paradigms. In particular, the enhancement data of the SVC coder are transmitted using MDC. The resulting fully compatible coder takes advantage of the efficiency of SVC and of the robustness of MDC techniques. The effectiveness of the proposed solution is confirmed by experiments.