The encoder arrangement, apart from the generally used circuitry consisting of a transform circuit (DCT), a quantizer (Q) and dequantizer (Qi) circuit, a packetizer/encoder (VLC), a substraction circuit (SUB) to determine the difference between a current and a previous image block, an adder circuit (AD) to add the above difference to a previous image block and a memory module (M) to memorize the mentioned previous image block, includes a selection circuit (SE) to select only part of the image block for memorization and a supplementing circuit (SU) to supplement the thus partly memorized image block with zeros to obtain a complete previous image block. In this way the memory capacity for memorization of the image blocks can be reduced.

Hybrid encoder arrangement for an image processing system

A video signal is coded by intraframe coding. The coded video signal is then decoded by intraframe/field decoding. While, a decoded local video signal is generated, which corresponds to a specific region in one frame of a video signal coded one frame prior to the video signal. A first motion signal is generated, which indicates motion of pictures in both the decoded video signal and the decoded local video signal. The motion signal is then subtracted from the video signal to generate a predictive error signal which is then coded by intraframe coding. The coded video signal and the coded predictive error signal are decoded by intraframe/field-decoding. A second motion signal is generated, which indicates motion of pictures in both the decoded video signal and a video signal decoded one frame prior to a video signal to be reproduced. The decoded predictive error signal and the second motion signal are added to each other to reproduce the video signal.

Video signal coding apparatus and decoding apparatus

Techniques are described that can be used to store macroblocks to memory and retrieve macroblocks from memory. In some cases, macroblocks can be stored in memory in memory addressable locations with column and row addresses flipped. Because macroblocks are stored in columns but retrieved across rows, portions of multiple macroblocks can be retrieved in a single read burst. The portions can be Golomb decoded and stored so that macroblocks can be re-assembled from the portions. In some cases, macroblocks of encoded video can be stored in continuous memory addressable locations.

Techniques for storing and retrieving pixel data

A mixture model for the connection holding times in the video-on-demand service

/pdf/extrapolation-of-wideband-speech-from-the-telephone-band-37ckv3mq94.pdf

Extrapolation of wideband speech from the telephone band

Coder-decoder of television pictures for transmission and/or reception via digital low-speed channel. In transmission, it first carries out the bidimensional transform of digital sample blocks of the television signal and then a dichotomic quantization thus obtaining quantized coefficients with variable length as a function of the coefficient index; in reception, it first carries out a quantization for quantized coefficients re-assignment of suitable quantization levels, and then the bidimensional antitransform for obtaining again the digital television signal samples. An optimized configuration of digital sample memory in transmission and in reception is shown in FIG. 1.

Coder-decoder for transmission and/or reception of television pictures via digital low-speed channel

The paper is presenting a sketch of the main results achieved in the recent years and of the ongoing activities (mainly within the Standardization Bodies) in the areas of audio and video coding for bandwidth reduction. The evolution of the telecommunication Field and the needs which originate the different standards are also considered.



The paper is organized in two main chapters: the first one is dealing with the techniques for audio and speech coding while the second presents the main achievements in terms of Recommendations and consolidate algorithms for image coding. Concerning speech and audio coding the paper presents and overview of the coding techniques and then examines the different environments of transmissions (network and mobile communication), the bandwidths required to satisfy the considered applications and the defined speech quality evaluation methods. A similar approach has been used for video coding and the evolution of the coding techniques appearing in the CCITT Recommendations is presented. The ongoing activities within CCIR, CMIT, CCITT and ISO towards new worldwide standards are also outlined providing indications on the areas which will require further developments.

Speech and image coding for digital communications

This paper describes the architecture implemented in five different countries to validate, by means of tests carried out with expert users, a service architecture for the interactive retrieval of multimedia information. The service architecture definition (which corresponds to the DAVIC 1.0 Specifications) and all activities for the set-up and running of the experiments, have been carried out within the RACE R2120 Multimedia Audiovisual Retrieval Services (MARS) project. A unique server and terminal architecture has been developed and put in operation at each site, while a combination of different public network solutions were used for the terminal access side. All national experiments made use of an ATM-based transport network. The interconnections between the five countries were provided by the European ATM Pilot (EAP). The minimal testbed configuration implemented in each country consisted of one server and two terminals. After the integration and test phases, this configuration was extensively tested within the national environment to obtain the users' perception of the service.

RACE “MARS” project for the experimentation of multimedia interactive services: Architecture solutions and results

The MPEG-2 standard has allowed Digital Television to become a reality at reasonable costs. The introduction of MPEG-4 will allow content and service providers to enrich MPEG-2 content with new 2D and 3D scenes capable of a high degree of interactivity even in broadcast environments. While ensuring compatibility with existing terminals, the user of the new terminal will be provided with other applications, such as Electronic Program Guides, Advanced Teletext, but also a new non-intrusive kind of advertisements. For these reasons, a scalable device opened both to the consolidated past (MPEG-2) and to the incoming future (MPEG-4) is considered a key issue for the delivery of new services. The presence of a Java Virtual Machine and a set of standard APIs is foreseen in the current terminal architecture, to give extended programmatic capabilities to content creators. This paper covers the application areas, the design and the implementation of a prototype for this terminal, which has been developed in the context of the ACTS SOMMIT project.

SOMMIT Project: Enabling New Services for the Next Generation of Digital TV Receivers

This paper considers one of the problems encountered in the definition of video coding algorithms for moving and still pictures due to the finite length arithmetic in the computation of orthonormal transforms. In particular two aspects are taken into account: mismatch and reversibility. The different causes which influence the final representation of the reconstructed video samples are examined and a formula is given, expressing said final error as a function of the errors introduced at the different stages of the computation. From an upper bound of said final error the minimum number of bits required for the representation of the quantities appearing at the different stages of the computation are derived for two cases of particular interest. Alternatively, assigning the length of the arithmetic registers, it is possible to know the worst case error. With some care the results are valid for any type of fast algorithms and not only for the matrix multiplication case which is used here to attain the widest validity of the results.

Mario Guglielmo

Papers

Coder-decoder for transmission and/or reception of television pictures via digital low-speed channel

Speech and image coding for digital communications

RACE “MARS” project for the experimentation of multimedia interactive services: Architecture solutions and results

SOMMIT Project: Enabling New Services for the Next Generation of Digital TV Receivers

On the arithmetic required in the computation of orthonormal transforms