Abstract: An Orthogonal Frequency Division Multiplexing (OFDM) receiver that compensates for FFT window drift by extracting a training symbol from a fast Fourier transformed OFDM signal, and processing the extracted training symbol to derive an FFT window adjustment factor and an associated equalizer tap initialization value. The OFDM receiver controls the position of an FFT window and the initialization of equalizer taps using the FFT adjustment factor and equalizer tap initialization value. The OFDM receiver preferably filters the fast Fourier transformed OFDM signal to remove additive channel noise and increase the likelihood of reliable equalizer tap initialization in a low SNR environment.

Abstract: Described is a TV system that uses a single pixmap across multiple video rasters having different raster sizes. In general, the TV system uses at least two headers to select different portions of a single pixmap to be displayed based on different raster sizes. Specifically, each of the two headers points to a single pixmap. In the TV system, the size of the central portion is fixed while the size of the sidepanel portion can be adjusted depending on the displaying mode. In response to different displaying modes, the TV system selectively invokes one of the two headers to select a respective portion to be displayed in the pixmap. By doing so, a single pixmap can be used across multiple video rasters having different raster sizes.

Abstract: The object of the invention is to provide a system for encoding grey levels which makes it possible to reduce the problems of contouring by increasing the number of subscans using subscans common to several rows, thereby remedying the error due to the difference between the grey levels of simultaneously scanned cells. The invention provides a method and a device which make row groupings dynamically according to the content of the image.

Abstract: An Orthogonal Frequency Division Multiplexing (OFDM) receiver detects and corrects sampling offsets in the time domain. The OFDM receiver oversamples a training sequence or symbol in a received OFDM signal, correlates the oversampled training sequence with a stored copy of a truncated version of the training sequence, locates a correlation peak, and derives a sampling offset by calculating a difference in magnitude of correlation samples in the vicinity of the correlation peak.

Abstract: An Orthogonal Frequency Division Multiplexing (OFDM) receiver that detects and corrects a carrier frequency offset of a received signal is provided. The OFDM receiver samples an incoming signal in the time domain and correlates the samples with a stored version of a training or reference symbol to generate a correlation sequence. A correlation peak is detected in the correlation sequence and the index of the correlation peak is set as a reference point. The OFDM receiver acquires a sample of the incoming signal that is a predetermined distance from the reference point. Next, the phase difference between the acquired sample and the local oscillator is computed. Afterwards, the frequency of the local oscillator is adjusted to reduce the computed phase difference. The acquired sample has a known phase that is equal to the phase of the local oscillator in the absence of a carrier frequency offset.

Abstract: An Orthogonal Frequency Division Multiplexing (OFDM) receiver that compensates for FFT window drift by extracting pilots from a fast Fourier transformed and equalized OFDM signal, and processing the extracted pilots to derive an FFT window adjustment factor and an associated equalizer tap adjustment value. The OFDM receiver simultaneously controls the position of an FFT window and the phase of equalizer taps using the derived FFT adjustment factor and equalizer tap adjustment value.

Abstract: The present invention is directed towards detecting contouring artifacts in a received video signal and reducing the detected artifacts by dithering and/or by adding least significant bits to selected pixels in the video signal. The contouring artifacts are detected by applying a magnitude difference test and/or an averaging test to a predetermined pixel span. The artifacts are reduced by substituting a replacement pixel for a selected pixel in the pixel span. A replacement pixel is generated by calculating an average pixel value for the predetermined pixel span, by reducing (e.g., rounding or truncated) the average pixel value to a bit resolution that is greater than the bit resolution of the pixels in the predetermined pixel span, or by adding a dither signal to the average pixel value.

Abstract: A memory management process for buffering progressive, interlaced, CCIR 601/656 compliant, and MPEG compliant video signals in a video memory that is partitioned into first and second buffers. The process includes identifying the format of a received video signal, buffering the received video signal in the video memory in accordance with a standard buffering mode if the video signal is in an interlaced, CCIR 601/656 compliant, or MPEG compliant format, and buffering the received video signal in the video memory in accordance with an override buffering mode if the video signal is in a progressive format such as a 240p signal generated by a game console, VCR, cable text generator, and the like.

Abstract: The process is characterized in that it stores a position of the write pointer PW on receipt of the synchronization signal S1 relating to the input signal so as to provide a value PW-IN, and on receipt of the synchronization signal S2 relating to the output signal so as to provide a value PW-OUT, in that it dynamically calculates an interpolation phase &agr; (12, 13, 14, 15) such that: α = P W ⁢   ⁢ _OUT - P W ⁢   ⁢ _IN Δ ⁢  

Abstract: An OFDM (orthogonal frequency division multiplexing) receiver that detects and corrects a sampling frequency offset of a sampled signal. The OFDM receiver samples an incoming signal in the time domain, multiplies the sampled data by a window function to widen the main lobe of each of the predetermined subcarriers' frequency domain spectrum, takes an FFT (fast Fourier transform) of the sampled signal to analyze the frequency domain samples of each predetermined subcarrier, detects a difference in magnitude of the frequency domain samples for each predetermined subcarrier, and generates a sampling frequency error based on the detected changes in magnitude.

Abstract: A transcoding method for inserting a visual element into an encoded bit stream with minimal decoding of the encoded bit stream. The transcoding method includes the steps of receiving an encoded bit stream containing a picture, partially decoding a copy of the bit stream, determining if a segment of the picture in the bit stream is affected by the insertion of the visual element, re-encoding the segment if the segment is affected by the insertion of the visual element, and outputting the re-encoded bit stream. The encoded and re-encoded bit streams may be MPEG-encoded bit streams. The re-encoded bit stream may be output using a bit rate control process that randomly selects an initial processing point within the re-encoded bit stream, requantizes the re-encoded bit stream using a modified quantization table, and/or utilizes a slice-level stopping criteria for selectively starting or ending bit rate control.

Abstract: The invention relates to a method of image compression, especially of the MPEG2 type, in which the images are coded according to groups (GOPs) each of which comprises N images, with an I image coded in intra mode, P images predicted as a function of the intra image I or of the preceding P image, each P image being preceded and followed by n bidirectionally predicted B images, n possibly being zero. The number M=n+1 represents the structure of the group. At least one parameter characterizing the source images which are to be coded according to a group is determined using a test coding (70), and the numbers N and M are made to depend on this parameter or these parameters. In the course of the test coding, defined values are conferred on N, M, and on the quantisation interval Q.

Abstract: The process is characterized in that the second data stream is modified before transmission, by replacing coding information for the first inter pictures of bidirectional type following the intra picture of the first GOP of the second sequence after the switching point, when considering the order of coding of the pictures, with predefined picture coding information whose coding cost is less than or equal to that of the initial pictures. Applications relate to the transmission and storage of programs, editing, etc.

Abstract: A seat belt adjuster which can be attached to the lap and shoulder belts of a conventional seat belt assembly so a passenger can adjust the positioning of the shoulder belt with respect to the passenger's upper torso. The seat belt adjuster includes a base and first and second pairs of flexible straps extending from the base. Each pair of straps can be interlocked to form first and second channels which slidably permit passage of the lap and shoulder belts therethrough. Each pair of straps can also be tighten to restrict the movement of the lap and shoulder belts through the first and second channels. In a preferred embodiment the first and second pair of straps are interlocked using Velcro strips. In an alternative embodiment a secondary locking loop, integral with one of the first or second pair of straps, is provided to strengthen the engagement of the first and second pairs of straps with the lap and shoulder belts.

Abstract: The process is characterized in that the pilot signals (10) generated upstream of the device (11) whose non-linearity it is desired to measure pass through a known non-linear device (15) delivering intermodulation products of known characteristics and in that at least one of the known intermodulation products is harnessed in order to modulate, with the aid of synchronous detection circuits (17), at least one of the signals relating to the components of the intermodulation products of the device to be measured.The applications pertain to the analog transmission of television signals over optical fibers.

Abstract: A transcoding method is performed by receiving a first bitstream of compressed image data having identifiable coding parameters. These parameters may relate to the GOP structure of pictures represented in the first bitstream, the size of the pictures represented in the first bitstream, whether the pictures represented in the first bitstream are field or frame pictures, and/or whether the pictures represented in the first bitstream define a progressive or interlaced sequence. First motion information is obtained from the first bitstream, and is used to extrapolate second motion information for a second bitstream of compressed image data. The second bitstream, which has one or more parameters different from the parameters of the first bitstream, is provided as a transcoded output.