Cirrus Logic Inc.

Daniel Gudmunson

John L Melanson

Rahul Singh

Ahsan Habib Chowdhury

A method and system for synchronizing video information derived from an asynchronously sampled video signals provide a mechanism for using asynchronous sampling in the front-end of digital video capture systems. A ratio between the sampling clock frequency and the source video clock frequency is computed via an all digital phase-lock loop (ADPLL) and either a video clock is generated from the ratio by another PLL, a number to clock converter or the ratio is used directly to provide digital synchronization information to downstream processing blocks. A sample rate converter (SRC) is provided in an interpolator that either acts as a sample position corrector at the same line rate as the received video, or by introducing an offset in the ADPLL, the video data can be converted to another line rate via the SRC.

Method and system for synchronizing video information derived from an asynchronously sampled video signal

A method and system for video-synchronous audio clock generation from an asynchronously sampled video signal provides a mechanism for maintaining synchronization of audio sampling in digital video-audio systems. A ratio between the sampling clock frequency and an audio reference frequency clock is computed via an all digital phase-lock loop (ADPLL) and an audio clock is generated from the ratio by another PLL or a number to clock converter. In systems where a sampling clock to source video clock ratio has been computed for recovering a video signal, the audio ratio can be computed directly from the video ratio.

Method and system for video-synchronous audio clock generation from an asynchronously sampled video signal

An adaptive equalization method and system for reducing noise and distortion in a sampled video signal improves the quality of output video information in both consumer and professional applications. A multi-band equalizer applied to the sampled video information reduces noise and distortion artifacts in the sampled video information. The gains of each of the equalizer bands is adjusted dynamically by control outputs provided by a noise and distortion detector. The noise and distortion detector incorporates circuits for comparing the luminance of each plane on a per-pixel basis with neighboring pixels and also includes a pattern matching comparator that detects edge features by comparing each pixel and its neighbors with a set of predetermined patterns. The noise and distortion detection can be further confirmed by comparing the detection results across multiple frames and the equalizer gain values may be further selected by a result of a video motion type classification.

Adaptive equalization method and system for reducing noise and distortion in a sampled video signal

A method and apparatus for maintaining an ideal frequency ratio between numerically-controlled frequency sources provides a mechanism for maintaining coherence between multiple synchronization references where a known ideal rational relationship between the sources is known. Multiple numerically controlled oscillators (NCOs) generate the multiple synchronization references, which may be clock signals or numeric phase representations and the outputs of the NCOs are compared with a ratiometric frequency comparator that determines whether there is an error in the ratio between the NCO outputs. The frequency of one of the NCOs is then adjusted with a frequency correction factor provided by the ratiometric frequency comparator. The NCO inputs can represent ratios of the synchronization reference frequencies to a fixed reference clock and the NCOs clocked by the fixed reference clock.

Growing community of inventors

Dripping Springs, TX, United States of America

Daniel Gudmunson