Technique for the transmission of video and audio signals over a digital transmission system

• US 4,544,950 A
• Filed: 01/03/1984
• Issued: 10/01/1985
• Est. Priority Date: 01/03/1984
• Status: Expired due to Fees

• Current Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated), Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: AT&T, Inc.
• Inventors: Tu, Peter J.
• Primary Examiner(s): Masinick, Michael A.
• Assistant Examiner(s): Parker, Michael D.
• Application Number:
  US06/567,538
• Time in Patent Office: 637 Days
• Field of Search: 358/143-146, 358/11, 358/13, 358/141, 358/142, 370/4
• US Class Current: 348/485
• CPC Class Codes: H04N 7/54 the signals being synchronous H04N21/23602, H04N21/23614, H04N21/2365, H04N21/2368, H04N21/4341, H04N21/4342, H04N21/4347, H04N21/4348 take precedence

Abstract

The present invention relates to a technique for transmitting both a video and a plurality of audio signals within a predetermined signal format which is compatible with a known signal format not normally used for television transmission. More particularly, the video signal is sampled at a first multiple of the video subcarrier frequency. The digitized video signal and associated video mode status bits are then multiplexed with the plurality of digitized audio signals into an N-bit frame format using a second multiple of the video subcarrier frequency which is less than the line frequency of the known signal format. The N-bit frames are then sectioned into Y-bit subframes and multiplexed with auxiliary and monitoring bit information comprising, for example, frame location bits for the Y-bit subframes using a third multiple of the video subcarrier frequency to generate a system signal format which is compatible with the known signal format. At a receiving end the system signal format is demultiplexed in a reverse manner to the multiplexing sequence at the transmitter.

Claims

1. A transmitter capable of transmitting a video input signal and a plurality of audio input signals over an output channel, the transmitter comprising:

first converting means capable of converting samples of the video input signal and associated video processor mode status signals into a video output signal including representative S-bit digital words using a sampling rate which is a predetermined multiple of a subcarrier frequency of the video input signal;

second converting means capable of converting each of the plurality of audio input signals into a separate representative digital output signal;

first multiplexing means capable of multiplexing the plurality of digital output signals from the second converting means into a digital output signal comprising a predetermined sequence of bits;

means capable of generating appropriate binary monitoring and supplementary data bits; and

second multiplexing means comprising

a first multiplexer capable of multiplexing the video output signal from the first converting means and the audio output signal from the first multiplexing means to generate a first output signal including sequential N-bit frames, each N-bit frame comprising alternating multiples of one or more audio bits and video processor mode status bits and each sequential multiple of the audio and video mode status bits is separated by a predetermined plurality of sequential video signal bits, and a second multiplexer capable of multiplexing the first output signal from the first multiplexer with the output signal from the monitoring and supplementary data bit generating means to generate an output signal comprising a signal format which includes alternating multiples of monitoring and supplementary data bits and sequential predetermined subframe portions of sequential N-bit frames forming the first output signal of the first multiplexer for transmission over the output channel.

2. A transmitter according to claim 1 wherein the transmitter further comprises compression means disposed between the first converting means and the second multiplexing means for appropriately compressing the representative digital words of the video signal at the output of the first converting means by a predetermined compression factor to provide a predetermined signal rate which is less than a signal rate of the output signal from the second multiplexer of the second multiplexing means.

3. A transmitter according to claim 1 wherein the first multiplexer of the second multiplexing means multiplexes the video output signals from the first converting means and the audio output signals from the first multiplexing means at a bit rate which is a second predetermined multiple of the subcarrier frequency of the video input signal and is less than a predetermined line rate of the output channel.

4. A transmitter according to claim 3 wherein the second multiplexer of the second multiplexing means multiplexes the output signals from the first multiplexer and the supplementary data bit generating means at a bit rate which is a third multiple of the subcarrier frequency of the video input signal and is substantially the same as the predetermined line rate of the output channel.

5. A transmitter according to claim 1 wherein the second multiplexer of the second multiplexing means multiplexes the output signals from both the first multiplexer and the supplementary data bit generating means at a bit rate which is a second predetermined multiple of the subcarrier frequency of the video input signal and is substantially the same as a predetermined line rate of the output channel.

6. A transmitter according to claim 1 wherein the output signal from the first multiplexer of the second multiplexing means includes N-bit frames comprising alternating pairs of audio bits and video mode status bits which are separated by said predetermined plurality of sequential video signal bits.

7. A transmitter according to claim 1 wherein the output signal from the first multiplexer of the second multiplexing means includes N-bit frames comprising alternating audio and video mode status bits which are separated by said predetermined plurality of sequential video signal bits.

8. A receiver capable of receiving an input signal comprising a digitized video signal, a plurality of digitized audio signals, and a plurality of monitoring and supplementary digitized data signals in a predetermined system signal format and at a predetermined bit rate, where (a) the video signal and the audio signals and (b) the predetermined system signal format are synchronized to a predetermined first and second multiple, respectively, of a video subcarrier frequency of the received video signal, the receiver comprising:

first demultiplexing means comprising

a first demultiplexer capable of demultiplexing, at the second multiple of the video subcarrier frequency, (a) the monitoring and supplementary data signals and (b) the audio and video signals in each system signal format into a first and a second output signal, respectively, and a second demultiplexer capable of demultiplexing the second output signal from the first demultiplexer into (a) a first output signal comprising the video signal and (b) a second output signal comprising the plurality of audio signals at the first multiple of the video subcarrier frequency;

second demultiplexing means capable of demultiplexing the plurality of audio signals in the second output signal from the second demultiplexer of the first demultiplexing means into a corresponding plurality of separate audio signal bit streams;

first converting means capable of converting each of the plurality of audio signal bit streams from the second demultiplexing means into a separate representative analog signal;

second converting means capable of converting the first output signal comprising the video signal from the second demultiplexer of the first demultiplexing means into representative analog samples; and

means capable of detecting the first output signal from the first demultiplexer of the first demultiplexing means and applying the monitoring and 44 supplementary data signals for a predetermined use.

9. A receiver according to claim 8 wherein the receiver further comprises expansion means disposed to receive the first output signal from the second demultiplexer of the first demultiplexing means for expanding the digital video signal by a predetermined expansion factor.

10. A receiver according to claim 8 wherein the second converting means uses a conversion sampling rate which is a third multiple of the video subcarrier frequency.

11. A receiver according to claim 8 wherein the second output signal from the first demultiplexer of the first demultiplexing means comprises N-bit frames including alternating pairs of audio bits and video mode status bits which are separated by a predetermined plurality of sequential video signal bits.

12. A receiver according to claim 8 wherein the second output signal from the first demultiplexer of the first demultiplexing means comprises alternating audio and video mode status bits which are separated by a predetermined plurality of sequential video signal bits.