Abstract: A digital signal is non-linearly processed without generation of alias components by modelling the required non-linear operation by the best available quadratic function. A transformation circuit for implementing the quadratic function ax.sup.2 +bx may be used. As a result, only the second harmonic of each original frequency component of the digital signal is generated. Space for accommodating the original frequency components and the second harmonics can be made either by sampling frequency up-conversion in an interpolation up-converting circuit which doubles the sampling frequency, or by bandlimiting the original digital signal to a quarter of the original sampling frequency. In either case, the second harmonics occur below the Nyquist limit and no alias components are generated. A video signal color corrector makes use of both of the above techniques.

Abstract: Apparatus for storing a video signal includes a signal compression arrangement constituted by a spatial two-dimensional sub-band filtering arrangement that filters a digital video signal to form data sets constituting respective sub-bands of the two-dimensional spatial frequency domain, a quantizer that quantizes the data sets in accordance with respective values which are such that the amount of quantization of one of the data sets constituting a sub-band to which dc luminance information of the signal is at least predominantly confined is less than the average of the amounts of quantization of the remaining data sets, and an entropy encoder that selectively encodes at least some of the quantized data sets so that the quantized data sets, as selectively entropy encoded, form a compressed video signal. The signal compression arrangement is followed by a storage arrangement for storing the compressed video signal.

Abstract: Apparatus for identifying edit points in a digital audio signal recorded on a record medium in association with a video signal and a time code signal, comprises a random access memory (3) for storing a reproduced segment of the digital audio signal and the associated time code signal, a monitor (2) for displaying the image corresponding to a reproduced portion of the associated video signal, a digital-to-analog converter for converting that part of the segment of the digital audio signal corresponding to the displayed image and read from the random access memory (3) by reference to the stored time code for reproduction by a loudspeaker (4), a video screen (6) for displaying the waveform of the analog-converted audio signal with a cursor (8) which relates the waveform to the image displayed on the monitor (2), and a register (7) for recording the time code read from the random access memory (3) and corresponding to a required audio edit point at which the cursor is positioned.

Abstract: In a digital phase detector arrangement, the combination of a digital phase detector for deriving a digital output signal representing the phase differences between two input clock signals supplied to the phase detector, and a circuit for reducing jitter in the output signal; the circuit comprising a differentiator for differentiating the output signal to produce a differentiated signal, a low-pass filter for low-pass filtering the differentiated signal to produce a filtered signal, and an integrator for integrating the filter signal to produce a further digital output signal from which at least some jitter has been removed by the low-pass filter.

Abstract: In order to permit three-component (left, right and back) audio signals (LS, RS, BS) to be conveyed by a three-channel (left, right and mono) transmission system and still permit stereo and mono compatibility, the signals are encoded so that the three channels carry LS-1/2BS, RS-1/2BS and LS+RS+BS, respectively. Upon receipt, the signals can be decoded back to LS, RS and BS respectively. In a mono receiver without such a decoder, the signal LS+RS+BS on the mono channel is employed, and in a stereo receiver the signals LS-1/2BS and RS-1/2BS on the stereo channels are employed.

Abstract: A television standards converter for converting an input digital video signal from one television standard to another, comprises a high-pass filter (36) for filtering the input video signal horizontally and vertically, a pluraity of parallel processing channels comprising respective circuits (43 to 58) for determining pixel by pixel of the high-pass filtered video signal the correlation magnitudes for a range of horizontal and vertical pixel offsets, low-pass filters (59) for filtering the resulting correlation magnitudes, a selecter (62) for determining for each pixel of said video signal, from the relationship between motion vector magnitude and the correlation magnitude, the motion vector corresponding to the maximum correlation magnitude, and a temporal interpolator (FIG. 14) for deriving interpolated fields or frames by combining sample values offset by the motion vectors.