A video frame arithmetical context adaptive encoding and decoding scheme is presented which is based on the finding, that, for sake of a better definition of neighborhood between blocks of picture samples, i.e. the neighboring block which the syntax element to be coded or decoded relates to and the current block based on the attribute of which the assignment of a context model is conducted, and when the neighboring block lies beyond the borders or circumference of the current macroblock containing the current block, it is important to make the determination of the macroblock containing the neighboring block dependent upon as to whether the current macroblock pair region containing the current block is of a first or a second distribution type, i.e., frame or field coded.

Video frame encoding and decoding

Compressed bitstreams are, in general, very sensitive to channel errors. For instance, a single bit error in a coded video bitstream may cause severe degradation on picture quality. When bit errors occur during transmission and cannot be corrected by an error correction scheme, error concealment is needed to conceal the corrupted image at the receiver. Error concealment algorithms attempt to repair damaged portions of the picture by exploiting both the spatial and the temporal redundancies in the received and reconstructed video signal. We discuss several temporal, spatial, and transform-domain error concealment techniques for MPEG coded pictures, and propose a new scheme based on directional interpolation. We also compare the performance of these techniques by computer simulation.

Error concealment based on directional interpolation

An apparatus and method for encoding of a video picture is disclosed. The video picture has a plurality of pictures. The pictures each have a plurality of macroblocks. The macroblocks each have a plurality of sub-blocks. The apparatus comprising a first module configured to generate a transform coefficient C ij for each of the sub-blocks of the macroblock. The apparatus further comprises a second module configured to variably quantize the transform coefficient by a scaling factor Q p based on the complexity of the picture and any rate control requirements.

An apparatus and method for motion video encoding employing an adaptive quantizer

Binarization a data value comprises binarizing the minimum of the data value and a predetermined cut-off value in accordance with a first binarization scheme, in order to yield a primary prefix. If the data value is greater than the cut-off value, binarizing a difference of the data value minus the predetermined cut-off value in accordance with a second binarization scheme to obtain a binary suffix, the first binarization scheme being different from the second binarization scheme, and appending the primary suffix to the primary prefix is performed. A very effective compression of data values may be achieved by using the binarization scheme for preparing the syntax elements for the arithmetic coding, the binarization scheme substantially being a combination of two different binarization schemes, and by using binary arithmetic coding instead of m-ary arithmetic coding for coding the binarized syntax elements.

Method and apparatus for binarization and arithmetic coding of a data value

A method and an arrangement for coding transform coefficients in picture and/or video coders and decoders and a corresponding computer program and a corresponding computer-readable storage medium are provided, which can particularly be employed as a novel efficient method for binary-arithmetic coding transform coefficients in the field of video coding. For this, it is suggested that, for blocks of (video) pictures containing significant transform coefficients, coding of the transform coefficients takes place in such a way that, for each block in a scan process, the positions of significant transform coefficients in the block and subsequently, in a reverse scan order—starting from the last significant transform coefficient within the block—the values (levels) of the significant transform coefficients are determined and coded.

Method and arrangement for coding transform coefficients in picture and/or video coders and decoders and a corresponding computer program and a corresponding computer-readable storage medium

We describe a motion compensated hybrid DCT/DPCM video compression scheme, which has been proposed for the storage of compressed digital video. The scheme, an extension of a current CCITT/ISO proposal for compressing still-frame images, differs from other hybrid DCT proposals in several ways. (1) Reduction of DCT block-artifacts by implementing inverse AC-quantizers which are of finer granularity than the corresponding encoder quantizers. This process, which we label ‘AC-Correction’, is applied to intraframe coded frames. (2) Entropy coding by means of an adaptive binary arithmetic coder. Arithmetic coding results in better compression efficiency than Huffman coding, thus improving image quality when a fixed bandwidth channel is available. (3) Non-linear loop filtering that preserves edge definition. (4) Tight tolerances in the rate control of groups of frames.

DCT coding for motion video storage using adaptive arithmetic coding

Stack filters are generalizations of median filters; a stack filter is a composition of local minimum and maximum operators. A major question in the study of these filters is whether a particular stack filter will make any signal of finite extent converge to an invariant signal--i.e. whether it will "filter out all the noise." Here, we consider the class of stack filters that reduce to symmetric threshold functions for binary inputs. We show that, if we surround an n-dimensional signal with an arbitrary fixed boundary, then any n-dimensional stack filter from the class will make the signal converge to an invariant signal, or a cycle of period 2, in a finite number of iterations. If we make the stack filter recursive, it will always filter the signal to an invariant signal, no matter how the filter moves over the signal. Our results follow from similar theorems on the convergence of neural networks. Many known useful filters are governed by our results. They include all 1-dimensional ranked-order filters with symmetric windows, and all 2-dimensional ranked-order filters with windows that are invariant under a 180° rotation.

Convergence properties of multidimensional stack filters

We have implemented three different video codecs in software for IBM's RISC System/6000 family of UNIX workstations. The codecs are Motion JPEG (M-JPEG), Intel's Indeo 3.1 codec, and IBM's Ultimotion Matinee codec. We implemented the codecs entirely in high-level languages. Here, we discuss and compare the performance of the three codecs. We consider both the characteristics of the encode/decode algorithms, and the speed of our decoder implementations on various models in the RISC System/6000 family. We especially wanted to examine each decoder's frame rate performance, using a common video sequence, across a range of different processors. Our tests showed that Motion JPEG provides the best image quality for a given bit-rate, while Ultimotion Matinee provides the fastest decode frame rate of the three decoders. For each decoder, the displayed frame rate tracks CPU performance. In general, software video decoders yield acceptable frame rates for most video sequences.

Peter Wendt

Papers

DCT coding for motion video storage using adaptive arithmetic coding

Convergence properties of multidimensional stack filters

A performance comparison of three software video codecs for IBM RISC System/6000 workstations