A video decompression system includes block error concealment means for generating substitute data for lost blocks of pixel data. An interpolator generates both spatially and temporally interpolated or predicted blocks of data for concealing a lost block. Pixel data in the respective blocks of spatially and interpolated data are transformed to coefficients representing frequency spectra. A substitute block of coefficients is assembled from coefficients from both the transformed blocks, according to a predetermined criteria. The substitute block is transformed back to the spatial domain for substitution of lost pixel values.
A video decoder is provided with robust error handling and concealment. In one embodiment, the video decoder detects syntactic, semantic, and coding errors in encoded slices of macroblocks. An error handler determines the number of remaining un-decoded macroblocks in the corrupted slice and replaces these corrupted macroblocks using substitute DCT coefficient matrices and motion vectors. The zero-frequency DCT coefficient of each substitute matrix is set equal to the zero-frequency DCT coefficient of the last uncorrupted macroblock, while the higher frequency DCT coefficients are set equal to zero. The substitute motion vectors are provided from a concealment vector memory which buffers the motion vectors of the previous macroblock row. In this way, intelligent approximations are made for the missing macroblocks, effectively masking the video bitstream error.
Motion correlation is a way of analyzing movement in image sequences such as television signals. The estimation of movement in television pictures is essential to enable the use of motion compensated processing techniques. These techniques yield improved quality video processing and moving image compression. Motion correlation would be used as part of a video motion estimation system. This invention describes a number of enhancements to, and a simplfied, efficient implementation of, the basic motion correlation algorithm. It is shown how to produce motion correlation surfaces co-timed with output, rather than input, pictures. It is also shown how to average power spectra to obtain improved noise performance, and hence improved accuracy, in motion correlation. Finally it is shown that separate correlation surfaces can be produced relating to `future` and `past` pictures.
The present invention provides a device (200, 300), system (400, 500) and method for real-time streaming of a multimedia file stored in a remote server over a packet network to a multimedia client connected to the same network via a low-speed access link such as an analog telephone line. The invention operates to provide significantly improved QoS with respect to both quality and delay.
An apparatus for use in a video signal decoding system for concealing errors in a video signal first detects a lost block in the video signal, the lost block having errors, and then provides pixel values of neighboring blocks for the lost block in the video signal based on information for the lost block. Subsequently, The apparatus computes edge gradients of neighboring pixels included in a predetermined range of pixels surrounding the lost block based on the pixel values of the neighboring blocks and determines a pixel interpolation direction based on the edge gradients of neighboring pixels. A spatially interpolated block is produced based on the pixel values of the neighboring blocks and the pixel interpolation direction and it is provided as a substitution block for compensating the lost block.
