1,824,166 research outputs found
Mode refinement algorithm for H.264 inter frame requantization
Full text linkThe latest video coding standard H.264 has been recently approved and has already been adopted for numerous applications including HD-DVD and satellite broadcast. To allow interconnectivity between different applications using H.264, transcoding will be a key factor. When requantizing a bitstream the incoming coding decisions are usually kept unchanged to reduce the complexity, but it can have a major impact on the coding efficiency. This paper proposes a novel algorithm for mode refinement of inter prediction in the case of requantization of H.264 bitstreams. The proposed approach gives a comparable quality to a full search for a fraction of its complexity by exploiting the statistical properties of the mode distribution and motion vector refinementThe latest video coding standard H.264 has been recently approved and has already been adopted for numerous applications including HD-DVD and satellite broadcast. To allow interconnectivity between different applications using H.264, transcoding will be a key factor. When requantizing a bitstream the incoming coding decisions are usually kept unchanged to reduce the complexity, but it can have a major impact on the coding efficiency. This paper proposes a novel algorithm for mode refinement of inter prediction in the case of requantization of H.264 bitstreams. The proposed approach gives a comparable quality to a full search for a fraction of its complexity by exploiting the statistical properties of the mode distribution and motion vector refinemen
Performance evaluation of transcoding algorithms for H.264
Full text linkThe latest video coding standard H.264 has been recently approved and has already been adopted for numerous applications including HD-DVD and satellite broadcast. To allow interconnectivity between different applications using H.264, transcoding will be a key factor. This paper assesses the existing requantization techniques developed for previous MPEG standards once adapted to H.264 together with a new technique. The proposed transcoding algorithm is based on a mixed requantization technique which gives a good compromise between complexity and quality. Those tests were used to define a plausible approach for a consumer oriented transcoder. © 2006 IEEE.The latest video coding standard H.264 has been recently approved and has already been adopted for numerous applications including HD-DVD and satellite broadcast. To allow interconnectivity between different applications using H.264, transcoding will be a key factor. This paper assesses the existing requantization techniques developed for previous MPEG standards once adapted to H.264 together with a new technique. The proposed transcoding algorithm is based on a mixed requantization technique, which gives a good compromise between complexity and quality. Those tests were used to define a plausible approach for a consumer oriented transcoder
Codificação de vídeo H.264: estudo de codificação mista de macroblocos
Full text linkDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Elétrica.Esta dissertação trata da codificação e compressão de vídeo digital, particularmente focando o recente padrão de codificação H.264. O interesse em tal padrão tem crescido bastante ultimamente, principalmente para o uso em novos sistemas de armazenamento e de transmissão de vídeo digital. O H.264 é um padrão de vídeo atual que possui muito bom desempenho - taxa de bits 50% menor do que a do seu antecessor MPEG?2, mantendo o mesmo desempenho de qualidade. Nesta dissertação, são abordadas duas extensões (aprimoramentos) ao padrão H.264, visando melhorar ainda mais o desempenho de tal padrão, isto é, aumentar a qualidade do sinal comprimido (mantendo a mesma taxa de bits), ou reduzir a taxa de bits (mantendo a mesma qualidade). As extensões fundamentam?se no fato de que alguns tipos de macroblocos (segmentos do sinal de vídeo) possuem uma pequena região distinta que geralmente tem influência negativa na taxa de bits. Inicialmente, são apresentadas as principais características da codificação de vídeo e do padrão H.264. Em seguida, um detalhamento dos diversos processos que estão relacionados aos aprimoramentos são considerados, principalmente nos processos de codificação de macroblocos, predição e otimização da taxa?distorção Lagrangiana. Para avaliar os novos modos de codificação, o código do modelo de referência (JM) de implementação do padrão H.264 é modificado para incluir tais extensões (tanto na codificação quanto na decodificação). Os resultados obtidos decorrentes das modificações propostas são avaliados através do uso de diversas seqüências?padrão de teste. Tais resultados indicam que os aprimoramentos conseguidos são passíveis de serem incluídos no referido padrão
Evolutionary strategy based improved motion estimation technique for H.264 video coding
No full textIn this paper we propose an improved motion estimation algorithm based on evolutionary strategy (ES) for H.264 video codec applied to video. The proposed technique works in a parallel local search for macroblocks. For this purpose (mu+lambda) ES is used with an initial population of heuristically and randomly generated motion vectors. Experimental results show that the proposed scheme can reduce the computational complexity up to 50% of the motion estimation algorithm used in the H.264 reference codec at the same picture quality. Therefore, the proposed algorithm provides a significant improvement in motion estimation in the H.264 video codec
Complexity adaptation in H.264/AVC video coder for static cameras
Full text linkH.264/AVC uses variable block size motion estimation (VBSME)
to improve coding gain. However, its complexity is significant
and fixed regardless of the required quality or of the
scene characteristics. In this paper, we propose an adaptive
complexity algorithm based on using the Walsh Hadamard
Transform (WHT). VBS automatic partition and skip mode
detection algorithms also are proposed. Experimental results
show that 70% - 5% of the computation of H.264/AVC is required
to achieve the same PSNR
A Novel H.264/AVC Based Multi-View Video Coding Scheme
Full text linkThis paper investigates extensions of H.264/AVC for compressing multi-view video sequences. The proposed technique re-sorts frames of sequences captured by multiple cameras looking at a person in a scene from different views and generates a single video sequence. The multi-frame referencing property of the H.264/AVC, which enables exploitation of the spatial and temporal redundancy contained in the multi-view sequences, is employed to implement several modes of operation in the proposed coding algorithm. To evaluate the performance of the proposed coding technique at different modes of operations, five multi-view video sequences at different frame rates were coded using the proposed and the simulcast H.264/AVC coding schemes. Experiments show the superior performance of the proposed coding scheme when coding the multi-view sequences at low and up to half of the original frame rates
The vanishing author in computer-generated works: a critical analysis of recent Australian case law
Full text linkAbstract
The use of software is ubiquitous in the creation of many copyright works, yet the requirement in copyright law that every work have a human author who engages in independent intellectual effort means that its use may prevent copyright subsistence. Several recent Australian cases have refocused attention on authorship as an essential criterion of copyright subsistence, and these cases suggest that much computer-produced output may be authorless and thus lack copyright protection. This article, the first in a two-part series, analyses how each case deals with the question of authorship of computer-produced works and why the use of software diminishes copyright protection for a significant number of computer-generated works. The article critiques the application of conventional notions of human authorship developed in the pre-computer age to modern productions and suggests alternative approaches to authorship that satisfy both the major objectives of copyright policy and the need to adapt to the computer age. The article argues that, without a broader judicial approach to authorship of computer-generated works, Parliament must remedy the lacuna in protection for these ‘authorless’ works. Possible solutions for reform are suggested. In a forthcoming article, the author comprehensively examines those reform proposals
Motion estimation and CABAC VLSI co-processors for real-time high-quality H.264/AVC video coding
Full text linkReal-time and high-quality video coding is gaining a wide interest in the research and industrial community for different applications. H.264/AVC, a recent standard for high performance video coding, can be successfully exploited in several scenarios including digital video broadcasting, high-definition TV and DVD-based systems, which require to sustain up to tens of Mbits/s. To that purpose this paper proposes optimized architectures for H.264/AVC most critical tasks, Motion estimation and context adaptive binary arithmetic coding. Post synthesis results on sub-micron CMOS standard-cells technologies show that the proposed architectures can actually process in real-time 720 × 480 video sequences at 30 frames/s and grant more than 50 Mbits/s. The achieved circuit complexity and power consumption budgets are suitable for their integration in complex VLSI multimedia systems based either on AHB bus centric on-chip communication system or on novel Network-on-Chip (NoC) infrastructures for MPSoC (Multi-Processor System on Chip
The 1895 Ljubljana earthquake: can the intensity data points discriminate which one of the nearby faults was the causative one?
No full textEfficient intra- and inter-mode selection algorithms for H.264/AVC
Full text linkH.264/AVC standard is one of the most popular video formats for the next generation video coding. It provides a better performance in compression capability and visual quality compared to any existing video coding standards. Intra-frame mode selection and inter-frame mode selection are new features introduced in the H.264/ AVC standard. Intra-frame mode selection dramatically reduces spatial redundancy in I-frames, while inter-frame mode selection significantly affects the output quality of P-/B-frames by selecting an optimal block size with motion vector(s) or a mode for each macroblock. Unfortunately, this feature requires a myriad amount of encoding time especially when a brute force full-search method is utilised. In this report, we propose fast mode-selection algorithms tailored for both intra-frames and inter-frames. The proposed fast intra-frame mode algorithm is achieved by reducing the computational complexity of the Lagrangian rate-distortion optimisation evaluation. Two proposed fast inter-frame mode algorithms incorporate several robust and reliable predictive factors, including intrinsic complexity of the macroblock, mode knowledge from the previous frame(s), temporal similarity detection and the detection of different moving features within a macroblock, to effectively reduce the number of search operations. Complete and extensive simulations are provided respectively in these two chapters to demonstrate the performances. Finally, we combine our contributions to form two novel fast mode algorithms for H.264/AVC video coding. The simulations on different classes of test sequences demonstrate a speed up in encoding time of up to 86% compared with the H.264/AVC benchmark. This is achieved without any significant degradation in picture quality and compression ratio
- …
