Coding and decoding system for video and audio signals

• US 4,424,532 A
• Filed: 05/09/1983
• Issued: 01/03/1984
• Est. Priority Date: 05/14/1980
• Status: Expired due to Term

• Current Assignee: Tv/com Technololgies, Inc.
• Original Assignee: Oak Industries, Inc. (Corning Incorporated)
• Inventors: den Toonder, Pieter, Fondse, Pieter J., Seltenrijch, Johannes, de Koningh, Tom, de Jong, Cornelis A.
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US06/492,706
• Time in Patent Office: 239 Days
• Field of Search: 358/120, 358/121, 358/124, 358/118
• US Class Current: 380/226
• CPC Class Codes: H04N 7/167 Systems rendering the television signal unintelligible and subsequently intelligible

Abstract

A coding and decoding system for video and audio signals includes means at the transmitter for deriving clock and internal timing signals from the video signal. The internal timing signals are utilized at the transmitter to provide digital audio data representative of the program audio signal. The digital audio data is derived by sampling the program audio signal during horizontal lines of the video signal. The synchronizing information in the horizontal and vertical blanking intervals of the video signal is suppressed and the digital audio data and data representative of a decoder clock signal are inserted in the horizontal blanking intervals. Vertical reference signal data is inserted into the vertical blanking intervals of the video signal as it is transmitted. At the decoder there are means for reconstituting the audio signal from the digital audio data. There is an independent sync pulse generator at the decoder which is controlled by the clock data and the vertical reference signal data and which provides the appropriate synchronizing information for the video signal. The video signal, without sync information, is combined with the separately generated sync pulses from the sync pulse generator and with the reconstituted audio to provide a television program signal usable at a conventional receiver.

Claims

1. Means for coding and decoding video and audio signals including:

(a) at the transmitter;

(1) means for deriving clock and internal timing signals from the video signal,

(2) means controlled by said internal timing signals for providing digital audio data during horizontal lines of the video signal,

(3) means for providing data representative of a decoder clock signal and a vertical reference signal,

(4) means for suppressing the video signal during horizontal and vertical blanking intervals,

(5) means for inserting the digital audio data and decoder clock signal data into suppressed horizontal blanking intervals,

(6) means for inserting vertical reference signal data into suppressed vertical blanking intervals,

(b) at the receiver;

(1) circuit means for separating the digital audio data, decoder clock signal data and vertical reference signal data from the video signal,

(2) means for independently generating a complete pattern of video signal horizontal and vertical sync pulses,

(3) a vertical reference signal data recognition circuit connected to said separating circuit and said sync pulse generator for detecting said vertical reference signal data and providing a gate signal to said sync pulse generator to start the pattern of horizontal and vertical sync pulses,

(4) a clock circuit connected to said separating circuit and to said sync pulse generator for detecting said clock signal data and providing clock signals to said sync pulse generator to control the timing of the pattern of horizontal and vertical sync pulses,

(5) means connected to said separating circuit for detecting said digital audio data and for providing a reconstituted audio signal,

(6) and means for combining the transmitted video signal, the reconstituted audio signal and the horizontal and vertical sync pulses from said sync pulse generator into television receiver usable video and audio signals.

2. The apparatus of claim 1 further characterized in that the means for providing digital audio data provides two sound samples per horizontal line.

3. Means for decoding television signals in which the synchronizing information during the video horizontal and vertical blanking intervals has been suppressed and in which digital sound data and clock data have been inserted in horizontal blanking intervals and in which vertical reference signal data has been inserted in vertical blanking intervals, including:

(a) circuit means for separating the digital audio data, decoder clock signal data and vertical reference signal data from the video signal,

(b) means for independently generating a complete pattern of video signal horizontal and vertical sync pulses,

(c) a vertical reference signal data recognition circuit connected to said separating circuit and said sync pulse generator for detecting said vertical reference signal data and providing a gate signal to said sync pulse generator to start the pattern of horizontal and vertical sync pulses,

(d) a clock circuit connected to said separating circuit and to said sync pulse generator for detecting said clock signal data and providing clock signals to said sync pulse generator to control the timing of the pattern of horizontal and vertical sync pulses,

(e) means connected to said separating circuit for detecting said digital audio data and for providing a reconstituted audio signal,

(f) and means for combining the reconstituted audio signal, the horizontal and vertical sync pulses and the video audio signal to provide a television signal usable in a conventional television receiver.

4. The apparatus of claim 3 further characterized in that said clock data is transmitted in the video signal horizontal blanking interval in binary form.

5. The apparatus of claim 3 further characterized in that said vertical reference signal data is transmitted in the video signal vertical blanking interval in binary form.