Techwell, Inc.

Chi-Hao Yang

Feng Yang

Feng Kuo

Chien-Chung Huang

Jao-Ching Lin

A video decoder for decoding a composite video signal. The decoder includes an analog-to-digital converter (ADC), an input resampler, and a Y/C separator, all coupled in series. The ADC receives and digitizes the composite video signal to generate ADC samples. The input resampler receives and resamples the ADC samples with a first resampling signal to generate resampled video samples. The Y/C separator receives and separates the resampled video samples into luminance and chrominance components. The Y/C separator includes a delay element configured to receive the resampled video samples and provide a variable amount of delay. The variable amount of delay can be adjustable from line to line, and is typically based on an approximated duration of a video line. For an NTSC signal, the variable delay is select to be (m&middot;n&plus;m/2) samples, where m is a ratio of frequencies of the resampling signal and a color subcarrier of the composite video signal, and n is an integer selected such that (m&middot;n&plus;m/2) samples most approximate the duration of a video line. For a PAL signal, the variable delay is selected to be (m&middot;n&plus;3m/4) samples.

Multi-standard video decoder

Techniques for enhancing edges in video signals while reducing the amounts of undershoots and overshoots. A video signal is processed to generate a first signal indicative of detected edges in the video signal. The first signal can be generated by lowpass filtering the video signal to generate a lowpass signal and subtracting the lowpass signal from a luminance signal that has been extracted from the video signal. The first signal is then processed with a &ldquo;non-linear&rdquo; transfer function to generate a second signal having enhanced edges. The second signal is used as the correction or enhancement signal, and is added to the lowpass signal to provide an output signal having enhanced edges with reduced or minimal amounts of undershoots and overshoots. The second signal has one or more of the following characteristics: (1) it is dynamically generated based on characteristics of the detected edges in the video signal; (2) it provides varying amounts of enhancement across the detected edges in the video signal; (3) it provides higher amounts of enhancement near the center of the detected edges and smaller amounts of enhancement away from the center; and (4) it provides an amount of enhancement that is dependent on the slope of the detected edges.

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San Jose, CA, United States of America

Chi-Hao Yang