Abstract: A method of operating a receiver, comprising: determining a location of the receiver by analyzing a broadcast signal received by the receiver, determining information for a user, the information being dependent on the determined location, and presenting the information to the user.

Abstract: For synchronising the operation of first and second video devices referenced by respective timecodes and operable at different video rates in response to first and second timing references where the first video rate is a m/n times the second video rate, a predetermined phase relationship is established between the first timecodes from the first video device and second reference signals for the second video device and then target timecodes for synchronising the second video device are derived from the first timecodes and the second reference signals. In a first embodiment second timing reference signals are generated with a fixed, repeatable phase relationship with respect to the first timecodes by resetting the timing of the second timing reference signals in response to a first timecode which, when divided by m, gives a predetermined remainder.

Abstract: Apparatus for decoding an input digital signal by replacing successive n-bit groups of the input digital signal with respective ones from an ensemble of m-bit data words, each m-bit data word having an associated n-bit code word, where n is greater than m, comprises: means for determining the Hamming distance between an n-bit group of the input digital signal and each of the n-bit code words associated with the ensemble of m-bit data words; and means for replacing that n-bit group of the input digital signal with an m-bit data word from the ensemble of m-bit data words for which the Hamming distance between the n-bit code word associated with that m-bit data word and that n-bit group is the lowest.

Abstract: Lighting effects for a digital video effects system are provided through a write-side process. An array of pixel values from a source video image is mapped onto an object surface to produce an output image by storing the input image pixels in a memory and then selectively addressing the memory in accordance with a function defining the object surface to form output pixels representative of the source video image mapped onto the object surface. Before storage in the memory, a write side lighting processor modifies the intensity of the source pixels. The source images are logically divided into tiles, a tile mapper calculates a mapping of the corners of the tiles onto the object surface and a lighting factor generator uses the mapped corner points to compute normals for individual pixels using interpolation. The dot product of the interpolated normals are computed and mathematically combined with other factors to generate lighting intensity modification factors for each of the pixels of the source image.

Abstract: An image data processing apparatus generates output data representing an image in a spatial domain from a plurality of sets of input data, each representing in a spatial frequency domain a sub sampled version of the image in the spatial domain. An error detector detects any erroneous parts of the plurality of sets of input data in the spatial frequency domain. Each of the plurality of sets of input data is transformed from the spatial frequency domain into a sub sampled version of the image in the spatial domain. Any parts of the sub sampled versions that are dependent upon an erroneous part of a set of input data are interpolated from one or more spatially adjacent parts of one or more other sub sampled versions. The sub sampled versions are combined to form the output data.

Abstract: A method of processing an input 60 field/second video signal generated by 3232 pulldown to produce an output video signal, comprises producing from the input signal a series of progressive scan format frames, each frame corresponding to a respective one of the input fields, and comparing blocks of pixels in each progressive scan frame with blocks of pixels in the following frame to derive motion vectors representing the motion of the content of respective blocks between frames. The motion vectors are utilized to monitor the field sequence of the input signal, and fields or frames of the output video signal are produced using input fields or progressive scan frames selected in dependence upon the field sequence of the input signal, at least some of the output fields or frames being produced by motion compensated temporal interpolation utilizing the motion vectors.

Abstract: A sampling frequency converter having an oversampler for operating on input data supplied to the converter, a signal processor for controlling operation of the sampling frequency converter and for generating oversampled output data from the oversampled input data, and a downsampler for generating output data at the output sampling frequency from the oversampled output data. The input and output of data by the signal processor are controlled by respective input and output interrupt signals, the output interrupt signal having a lower interrupt priority than the input interrupt signal.

Abstract: In order to simulate, on set or on location, a subsequent video to film conversion process, an input interlaced video signal is converted in any of a variety of ways to a progressive scan format video signal, and then interlaced fields of the progressive scan format frames are displayed on a video monitor or view finder.

Abstract: An image signal processing system is described in which image data in an interlaced format is converted to full frame format prior to application of any vertical processing, A swing buffer 40 is employed with Field 0 being written into the even addresses of a DRAM 44 forming one side of the swing buffer under control of an write controller 48. Field 1 is written into the odd addresses, The data in full frame format is read from consecutive addresses in the DRAM 44 into a signal processing engine 62 whilst the next frame is being written into the DRAM 46 forming the other arm of the swing buffer 40. This arrangement allows data that was captured in full frame format to be vertically processed in full frame format thereby preserving its vertical resolution. The full frame image data was converted out of full frame format prior to receipt by the image processing system for compatibility with hardware developed for interlaced format data.

Abstract: A video replay store controller wherein appropriate ones of a plurality of field stores are selected for storing replayed video data in a digital video tape recorder (DVTR). The controller comprises a transition detector associated with each of a plurality of video replay heads, for detecting changes in field identifiers associated with consecutively replayed video data blocks received from that video replay head, thereby detecting a field transition in the data replayed by that video replay head.

Abstract: A time base changer for a video converter for converting between a sequence of input video images at an input video rate and a sequence of output video images at an output video rate is operable to convert from one of a number of input video rates to an output video rate. The time base changer includes N video stores 32 where N is a integer greater than one, each for storing a video image. The video stores are enabled cyclically and at the appropriate input video rate for storing successive input video images in successive video stores. Multiplexers 36 connected to the video stores can output pairs of video images from the video stores at the output video rate. The time base changer includes a counter 38 which can be clocked at the appropriate one of the input video rates. The counter is preferably a modulo-N counter.

Abstract: A serial data decoder is described for decoding interleaved variable length and fixed length codes. The decoder includes a state machine which moves between a branching hierarchy of states in dependence upon the bits of received serial data. When the state machine reaches a state corresponding to a complete variable length code having been received, it then enters a delay state lasting for the length of time necessary to receive the following fixed length code prior to return to a reset state. The state machine can be implemented using a static ram 10 storing data including pointers for controlling the movements between states.

Abstract: Data formatting apparatus for formatting variable bit length data words into successive fixed bit length data words comprises an N-bit circular buffer comprising a plurality of concatenated buffer sections, each buffer section having the same bit length as one of the fixed bit length data words. A modulo-N counter generates a count of the cumulative length of received variable bit length data words. Each received variable bit length data word is stored in the N-bit circular buffer at a bit position dependent on the count signal, and, in response to a detection that data has been stored in all of the bits of that buffer section, the stored data from that buffer section is output as a fixed bit length data word.

Abstract: A serial data decoder is described employing a bank of parallel primary Huffman decoders 70 each operating to decode a stream of variable length code words with embedded control code words into a stream of fixed length index values. The fixed length index values are fed to a secondary decoder which operates under control of the fixed length index values representing control code words to decode the fixed length index values representing the variable length code words into output data.

Abstract: Image processing apparatus is described in which a source stream of data captured by a particular source is passed through a data splitter where it is split using one splitting technique into a plurality of split streams of data. These split streams of data each contain only part of the information within the source stream of data. The split streams of data are separately manipulated by a post production unit prior to being passed through a data combiner where they are recombined to form an output stream of data. The source stream of data and the output stream of data are of a higher resolution than the individual split streams of data. The post production unit includes at least one reformatter for reformatting the data stream to use a different splitting technique matched to the manipulation being performed in the post production unit.

Abstract: In order to reduce the effects of discontinuities at the edge of a picture and reduce erosion of the usable picture area caused by a filtering or interpolation operation, the edges of the picture are extrapolated prior to such an operation. This may be achieved by a circuit which receives an input line of active pixel data; forms from the input line a delayed line of the active pixel data; produces at least one additional start pixel data derived from a pixel data at or adjacent the start of the input line; produces at least one additional end pixel data derived from a pixel data at or adjacent the end of the input line; and forms an output sequence of pixel data by selecting for the output sequence the additional start pixel data, then at least part of the delayed line, and then the additional end pixel data. This circuit therefore performs zero-order (repeat) extrapolation at the beginning and end of each line.

Abstract: Digital filters are described for filtering blocks of data values. In order to reduce edge effects, symmetric data extension at the edges of the blocks is used. Multiplexers 34, 40, 46, 52 are used to pass data values between non-adjacent delay elements 36, 38, 42, 44, 48, 50 at leading and trailing edges of a data block to effect symmetric extension. The delay elements can be multisample delay elements and data being filtered can be multiplexed data.

Abstract: A video image filtering system is described which utilises multi-tap filters (70). In order to reduce the effects of edge distortion due to the finite size of the input image, extension data is added both the beginning and end of each raster line of data fed to the multi-tap filter (70). The function of the extension data is to pre-load the multi-tap filter (70). With a system constrained to operate at a constant sample rate, there is insufficient inter-raster line separation to accommodate the extension data needed for a long multi-tap filter (70). The system transforms the input video signal format (24) to a reformatted video signal format (28, 30) in which either the horizontal blanking or vertical blanking period has been maximised at the expense of the corresponding other blanking period.

Abstract: A motion compensation image processing apparatus and method for generating motion vectors that represent image motion between a pair of input images from which an output image is derived by motion compensated interpolation. A plurality of motion vectors are generated for each pixel of the output image and it is determined whether respective test blocks of each of the pair of input images, pointed to by each of the plurality of motion vectors, lie partially outside their respective input images. If one or both of the test blocks lies partially outside its respective input image, the degree of correlation between the test blocks is detected by performing a first correlation test on parts of the test blocks lying inside their respective input images. However, if both of the test blocks lie wholly inside their respective input image, the degree of correlation between the test blocks is detected by performing a second correlation test.

Abstract: Error concealment apparatus for concealing corrupted data elements in frequency separated digital image data (such as sub-band coded image data) is described. Depending on the spatial frequency represented by a corrupted data element, one of a number of error concealment means is selected to conceal the error. In this way the error concealment used can be tailored to suit the different properties of the various spatial frequency components in the frequency separated image.