US 4,361,852 AGranted

Signal processing circuit for video signal with buried audio signal

AssigneeSony Corporation

InventorLance J. Katzfey

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Abstract

An audio signal is time-compressed and injected as a buried audio signal into one or more selected line-scanning periods of a video signal, preferably during the vertical blanking portion of each field period. An encoding circuit for performing this function includes a memory device and a clock generator for providing to the memory device a high-speed clock signal during the selected line-scanning periods of each field period, and a low-speed clock signal during the remainder of the video signal. In the encoding circuit, a continuous audio signal is written into the memory device at low speed during substantially all of each field period and is read out therefrom at high speed during the selected line-scanning periods as a buried audio signal. In a complementary decoding circuit, the buried audio signal is written into a memory device at high speed during the selected line-scanning period and is read out therefrom at low speed during the remainder of each field period to reconstruct a substantially continuous audio signal. The memory device can be an analog device such as a CCD shift register, or can be a digital memory with associated A/D and D/A converters.

Claims16

Dependent claims

A circuit for processing a composite video signal formed of a video signal having a series of field periods each constituted by a sequence of line-scanning periods and of a buried audio signal occurring in at least one selected line-scanning period of at least certain field periods;

comprising:
audio channel means for receiving and processing said buried audio signal to yield a substantially continuous audio signal, including first memory means into which said buried audio signal is written and from which said substantially continuous audio signal is thereafter read out at a speed depending on the frequency of a clocking signal applied thereto, second memory means into which said buried audio signal is written and from which said substantially continuous audio signal is read out at a speed depending on the frequency of a clocking signal applied thereto, and selecting means for selecting said first and said second memory means to provide said continuous output signal so that the latter is free of gaps corresponding to the times of said selected line-scanning periods;
clocking signal generating means for generating a first clocking signal at a first clocking frequency and a second clocking signal at a second, higher clocking frequency;
and
clock control means for selectively applying said second clocking signal to said first and second memory means during said at least one selected line-scanning period and for selectively applying said first clocking signal to said first and second memory means during the remainder of said line-scanning periods, so that said buried audio signal is written into said first and second memory means at said second clocking frequency during said at least one selected line-scanning period and the written-in buried audio signal is read out of said memory means during substantially all of each field period to yield said substantially continuous audio signal.

2 more elements

Dependencies are inferred from the claim text.