摘要:
Error concealment apparatus for correcting errors in signals representing video images includes means for detecting image gradients in an area surrounding a lost block of image data. Circuitry responsive to these image gradients generates a plurality of blocks of directionally interpolated pixel values. The pixel values in the respective blocks of directionally interpolated pixel values are sorted according to amplitude, and then pixel values from mutually exclusive positions in the respective blocks are selected to form a block of pixel values for error concealment.
摘要:
Image reproduction is improved in an MPEG-like television receiver by inclusion of post-processing adaptive error concealment. Compressed video signal is examined to determine blocks of video signal containing errors, and error tokens are generated for identifying corresponding blocks of decompressed pixel values. Pixel values adjacent the decompressed blocks of pixel values containing errors are examined to generate estimates of the relative image motion and image detail in the area of such blocks. The block of pixel values is replaced with temporally displaced co-located blocks of pixel values or interpolated data depending upon whether the estimate of image motion is lesser or greater than the estimate of image detail.
摘要:
A dynamically configurable video signal processing system including an encoder and decoder processes data in the form of hierarchical layers. The system partitions data between hierarchical layers and allows variation in the number of layers employed. Data is automatically partitioned into one or more hierarchical layers as a function of one or more parameters selected from available system bandwidth, input data rate, and output signal quality. In addition, the image resolution and corresponding number of pixels per image of the data may be varied as a function of system parameters.
摘要:
An apparatus and concomitant method for selecting a macroblock coding mode based upon the quantization scale selected for the macroblock. The total number of bits needed to code each macroblock consists of two parts, bits needed for coding motion vectors and bits for coding the predictive residual. The number of bits for coding the motion vectors is generally obtained from a look-up table. The number of bits for coding the predictive residual is obtained by an estimation which assumes that the number of bits for encoding the predictive residuals is directly proportional to the value of its variance and inversely proportional to the value of quantizer steps (quantizer scale). Using this estimation, the total number of bits necessary to code a macroblock is calculated and compared for each coding mode. By selecting the coding mode with the least number of bits, a near-optimal solution of low complexity for practical implementation is acquired.
摘要:
A method and apparatus for selecting a quantizer scale for each macroblock to maintain the overall quality of the video image while optimizing the coding rate. A quantizer scale is selected for each macroblock such that target bit rate for the picture is achieved while an optimal quantization scale ratio is maintained for successive macroblocks to produce a uniform visual quality over the entire picture. One embodiment applies the method to the frame level while another embodiment applies the method in conjunction with a wavelet transform.
摘要:
A method and apparatus for down-converting a digital video signal includes a synthesizer and a converter. The synthesizer receives a digital video signal including at least first and second DCT blocks of DCT coefficients, and synthesizes the first and second DCT blocks into a single synthesized DCT block having dimensions equal to the first and second DCT blocks. The converter converts the synthesized DCT block from the DCT domain to the spatial domain to produce an output digital video signal.
摘要:
A digital video signal processing system includes apparatus for concealing errors which might occur in reproduced images due to image data lost during signal transmission. The system includes circuitry for detecting transmitted video data, generating error signals if errors are present in segments (transport blocks) of the received data, and excising segments having errors from the data stream. The received data is applied to a decoder/decompressor system which decodes and decompresses the transmitted video data according to a predetermined sequence and applies the decompressed video data to a memory (for subsequent display or recording, etc.). The decompressor is responsive to the error signals for altering the predetermined sequence.