Abstract: A technique for generating coefficients for a digital filter. A gain control signal with a value of reference gain and a frequency control signal with a value of reference frequency are provided. A plurality of gain and/or frequency points are calculated, according to a model of the frequency/gain characteristic of a prototype analog filter, at frequencies equal to and less than a Nyquist frequency (where the Nyquist frequency is half the sampling frequency of the digital frequency) and which match corresponds to gain and/or frequency points in the corresponding digital filter characteristic. Pre-warped parameters of a model of the analogue filter are calculated from the calculating points and a transform is applied to the resulting pre-warped analogue model, thus, converting the pre-warped analog model into the digital domain. Coefficients from the transformed model are generated and applied to the filter, thereby generating the coefficients of the digital filter.

Abstract: A digital audio signal processor processes digital audio signals having a first sampling rate S1. The processor has a multiplicity of manually adjustable controls (403) for setting desired parameters of signals to be processed. Sampling means (404) sample each control (403) setting at a second sampling rate S2 less than the first rate S1 to determine the settings thereof. Applying means (401) responsive to the sampling means apply the sampled settings to the signals. For each control the applying means determines the difference of successive samples of setting and applies to the signal, subject to control by that control, increments of setting each increment being a predetermined fraction 1/n of the said difference at a rate nS2 which is n times the said second sampling rate S2.

Abstract: An audio amplifier circuit comprises a voltage-gain amplifier and a current-gain amplifier in series between an input node and an output node. Power supply lines are provided for providing power to the audio amplifier circuit. An outer negative feedback loop is provided around the current gain amplifier and the voltage gain amplifier, and an inner negative feedback loop is provided around the voltage gain amplifier. A first switch is provided for selectively connecting the power supply lines to the current-gain amplifier. A second switch is provided for selectively switching the inner negative feedback loop or the outer negative feedback loop to the voltage-gain amplifier. A control circuit is also provided to control the switches during power supply switching.

Abstract: An image processing apparatus processes input signal samples representative of at least part of a color video image to produce legal color signal samples. An over sampled version of the input signal samples is produced. A plurality of adjustment factors are generated which, when combined with the input signal samples, have the effect of converting illegal color pixels of the color image into legal color pixels. The over sampled legalized color signal samples are decimated, resulting in a sampling rate corresponding to that of the base input signal samples, by selecting signal samples from the over sampled version of the legalized color signal samples which have not changed with respect to the corresponding input signal samples.

Abstract: Video signal processing apparatus in which at least first and second input video signals are combined to generate an output compressed video signal, the first and second video signals each having respective associated motion vectors from a data compression process applied to the video signals; comprises: means for establishing a set of the motion vectors associated with the first and second video signals which can potentially be re-used in compressing the output compressed video signal; and means for testing the set of motion vectors, the testing means being operable: (c) to define, with respect to reference images referred to by the motion vectors under test, a first border region of a predetermined width surrounding those parts of the reference images derived in part from the first video signal, and a second border region of a predetermined width surrounding those parts of the reference images derived in part from the second video signal; and (d) to test whether motion vectors of the set which are assoc

Abstract: A video signal processor comprises a first input for receiving a compressed first video signal including parameters associated with the frames of the signal and relating to the compression. A decoder decodes the compressed first video signal while preserving the parameters in association with the frames. A second input receives additional video information to be combined with the first video information. A combiner superimposes the additional video information on the first video information. An encoder encodes the combined video information. The encoder reuses the preserved parameters for encoding at least parts of the combined information which are not derived from the superimposed video information.

Abstract: Video special effects apparatus comprises a core program object; and a plurality of render processor plug-in program objects responsive to the core program object, the render processors being arranged in directed acyclic graph, each operable to render an output result relating to successive images of a video signal from input data relating to that and/or other images received from a preceding render processor in the directed acyclic graph and in response to operational parameters relating to that render processor; in which each operational parameter is defined by a parameter plug-in object arranged to communicate a parameter value to the render processor plug-in object.

Abstract: A method of receiving and demodulating a plurality of digital signals transmitted with different respective carrier frequencies and a digital receiver for receiving and demodulating a plurality of digital signals transmitted with different respective carrier frequencies wherein the carrier frequency signals are down converted to respective base-band signals and digitized and a common demodulator is provided to demodulate the respective digitized base-band signals in a time division manner.

Abstract: Decoders A and B decode MPEG-2 bitstreams A0 and B0 and re-encoders 8 and 10 re-encode them as bitstreams AI and BI comprising only I frames. A switch (S1) switches from recoded stream AI to recoded stream BI to achieve a splice AI/BI. The spliced bitstream is stored in an I-frame store (12). The stored bitstream AI/BI is re-encoded in an encoder 4. A new transitional GOP is defined beginning at the splice. The new GOP is defined by picture type decision rules which may change the length of the transitional GOP compared to the GOPs of streams A and B. The transitional GOP provides a prediction of the position in stream B where the occupancy value of stream C should coincide with that of B. A target for the new number of bits in the new GOP is calculated dependent on the difference between the occupancy value of stream C at the splice and a prediction of the occupancy of stream B at the predicted position.

Abstract: A method of digital image processing for detecting whether a test point within a digital representation of an image lies inside or outside a closed curve defined by an ordered series of curve points within the representation of the image, comprises the steps of: (i) detecting an angle subtended at the test point by pairs of the curve points adjacent to one another in the ordered series; (ii) summing the detected angles for all pairs of the curve points adjacent to one another in the ordered series; and (iii) detecting whether the summed angle is equal to a non-zero integral multiple of 360°, thereby indicating that the test point lies within the closed curve.

Abstract: A digital video receiver, a conditional access module and method of transmitting data therebetween, the digital video receiver having a multi line socket for connection to the conditional access module, the socket having a pre-determined plurality of lines for transmitting and receiving transport stream data and a pre-determined plurality of lines for transmitting and receiving control data and resource/application data, the method comprising selectively transmitting resource/application data over the plurality of transport stream lines.

Abstract: Video processing apparatus in which input images of an input video sequence are processed according to user adjustable video effects parameters to generate output images of an output video sequence comprises: rendering means for rendering images of the output video sequence according to a priority order of: (i) an image or images currently displayed for view by a user; (ii) first and last images of the output video sequence; and (iii) remaining images of the output video sequence.

Abstract: A signal processing system in which a differentially quantized digital signal is used, the digital signal having two bits which represent only three values, of which one value (10 or 01) is zero and the other two (11 and 00) values represent a positive value and a negative value respectively.

Abstract: A charge pump pair implemented by CMOS transistors comprises two charge pumps switchable to output a current of positive and negative polarity, respectively. Each charge pump comprises a current mirror including a reference current source, a logging transistor supplied with a reference current from the reference current source and a mirror transistor, the gate of the mirror transistor being connected to the gate of the logging transistor circuit to mirror an image of the reference current as the output of the charge pump. Each charge pump further include a clamp transistor switchable to selectively clamp the control input of the mirror transistor to switch the output of the mirror transistor on and off. The charge pumps are relatively scaled to equalize the rise time constants of the transient outputs of the charge pumps when switched on and the fall time constants of the transient outputs of the charge pumps when switched off.

Abstract: Video special effects apparatus comprises a plurality of video special effects processing modules; a display screen; a palette area on the display screen, the palette area displaying module screen icons representing video special effects processing modules; a graph area on the display screen; user-operable means for moving screen icons from the palette area to the graph area and for graphically linking the screen icons together to form a representation of a composite video special effects process; and user-operable means for a group of selecting two or more linked screen icons displayed in the graph area and transferring the group to the palette area, the group being represented in the palette area as a composite process screen icon in the palette area.

Abstract: A security control system comprises n inputs (C1-C128) for receiving video signals from n cameras. A video switcher (2) including a programmable controller (4) is programmable to connect any one of the n inputs (C1-C128) to any one of m outputs (R1-R28) where m is less than n, in any selectable time sequence. A display control means (6, 8) connects the m outputs (R1-R28) of the switcher (2) to p displays (M11-M22) via p channels each associated with m/p of the outputs of the switcher. The display control means (6, 8) has a programmable controller (10, 12) linked to the controller (4) of the switcher to selectively scale and position the images represented by the video signals on the displays in desired display formats and to define sequences of displays.

Abstract: A signal generator for use in a wipe generator comprises a first ramp generator which produces a video ramp signal R1 for each pixel of a predetermined set of pixels h where h=0 to n of each of a predetermined set of video lines v where v=0 to m, of a picture, wherein R1=A1h+B1v+C1 where A1, B1, and C1 are coefficients each having a magnitude equal to or greater than zero, and a second ramp generator which produces a video ramp signal R2 for each pixel of a predetermined set of pixels h where h=0 to n of each of a predetermined set of video lines v where v=0 to m of the picture, wherein R2=A2h+B2v+C2 where A2, B2, and C2 are coefficients each having a magnitude equal to or greater than zero. A2 and B2 are varied in accordance with the change in an angle of rotation, and the first and second ramps are combined by non-additively mixing.

Abstract: A system for generating a variety of solid signals and key signals. The system includes a multiple of solid generators, a multiple of key signal generators and a cross-point switch. Each of the solid generators includes a multiple of solid mixers, and each of the key signal generators includes a multiple of key signal mixers. The cross-point switch is arranged to connect any of the solid generators and key signal generators to any of the switch's main outputs, and to connect any of the solid generators to any of the key generators. The system provides for selection of preset delays to compensate for different signal routings. A timing control controls routing and delay selection.

Abstract: A soft windowing technique involves the use of a window for vector assisted frame differing, the window being larger than a macroblock of the structure defined over the video picture. The edges of each window taper so that overlapping windows provide the correct pixel weighting at the edges. For a scheme having 16*16 luminance macroblocks and 8*8 chrominance macroblocks, the luminance window is 24*24 and the chrominance window is 12*12.

Abstract: This is a design for a microphone which directly outputs a one-bit digital audio signal. No electronic analogue-to-digital converter is required.