System and method for synchronized presentation of video and audio signals

• US 5,570,296 A
• Filed: 03/30/1994
• Issued: 10/29/1996
• Est. Priority Date: 03/30/1994
• Status: Expired due to Term

• Current Assignee: Apple Computer Incorporated (Apple Inc.)
• Original Assignee: Apple Computer Incorporated (Apple Inc.)
• Inventors: Heyl, Lawrence F., Kannapell, Henry N.
• Primary Examiner(s): Ramirez, Ellis B.
• Assistant Examiner(s): PEESO, THOMAS R
• Application Number:
  US08/219,950
• Time in Patent Office: 944 Days
• Field of Search: 364/514 R, 370/20, 370/100.1, 370/113, 369/30, 340/825.14, 340/825.15, 340/825.2
• US Class Current: 709/231
• CPC Class Codes: H04N 21/4302 Content synchronisation processes, e.g. decoder synchronisation
• CPC Class Codes: H04N 21/4341 Demultiplexing of audio and video streams

Abstract

A system and method for synchronized presentation of audio and video signals initially stored on a computer. A single composite file containing synchronized information characterizing the signals is generated. The data in the file is supplied as a stream to the input of a demultiplexer. Data characterizing each signal is output through one of a plurality of outputs of the demultiplexer, and supplied to one of a plurality of signal processors that generates the respective signal.

Claims

1. A system for providing synchronized wide and narrow bandwidth signals, comprising

a channel for a composite digital data stream, said composite digital data stream comprising a first signal having a wide bandwidth and a second signal having a narrow bandwidth, said first and second signals composited as a single stream of synchronized data, and

a demultiplexer having

an input connected to said channel to receive said composite digital data stream,

a first output providing first demultiplexed digital information corresponding to said first signal, and

a second output providing second demultiplexed digital information corresponding to said second signal.

2. The system of claim 1 wherein said wide bandwidth is suitable for one or more video signals and said narrow bandwidth is suitable for one or more audio signals.

3. The system of claim 1 further comprising

a first signal processor connected to said first output of said demultiplexer for converting said first demultiplexed digital information to a first synchronized output signal,

a second signal processor connected to said second output of said demultiplexer for converting said second demultiplexed digital information to a second synchronized output signal, synchronized with said first synchronized output signal.

4. The system of claim 3 wherein each of said first and second signal processors comprises a digital-to-analog converter connected to a low-pass filter.

5. The system of claim 3 wherein said first signal comprises high frequency data having a plurality of high frequency components, wherein each of a first and a second high frequency component of said plurality of high frequency components is composited as a separate signal and synchronized with each other in said composite digital data stream.

6. The system of claim 5 wherein said second signal comprises

low frequency data encoded as a first series of second bits and

said first high frequency component encoded as a first series of first bits,

said low frequency data and said first high frequency component synchronized by replacing one or more least significant bits of said first series of first bits with a corresponding number of bits from said first series of second bits.

7. The system of claim 6 wherein said second signal comprises low frequency data having a plurality of low frequency components, wherein

a first low frequency component of said plurality of low frequency components is encoded as said first series of second bits and

a second low frequency component of said plurality of low frequency components is encoded as a second series of second bits, and where

said second high frequency component is encoded as a second series of first bits,

said first low frequency component and said second high frequency component synchronized by replacing one or more least significant bits of said second series of first bits with a corresponding number of bits from said second series of second bits.

8. The system of claim 7 wherein

said first high frequency component comprises video in phase chrominance data,

said second high frequency component comprises video quadrature chrominance data,

said first low frequency component comprises audio data, and

said second low frequency component comprises audio synch data.

9. The system of claim 7 further comprising a television signal encoder having inputs connected to synchronized signals corresponding to said first and second outputs of said demultiplexer.

10. A method for generating a synchronized signal from synchronized, digitized wide and narrow bandwidth signals, said method comprising:

providing composite digital data comprising a first signal having a wide bandwidth and a second signal having a narrow bandwidth, said first and second signals composited as a single stream of synchronized data,

supplying said composite digital data to an input of a system comprising a demultiplexer having a first output comprising a first output signal having said high frequency and a second output signal comprising said low frequency, said second output signal synchronized with said first output signal.

11. The method of claim 10 wherein said composite digital data is an interleaved sequence of samples of said first and second signals.

12. A method for generating a synchronized signal from synchronized wide and narrow bandwidth signals, said method comprising:

converting a first signal having a wide bandwidth to a first digital signal at a selected sampling rate,

converting a second signal having a narrow bandwidth and synchronized with said first signal to a second digital signal at a selected multiple of said selected sampling rate,

subdividing said second digital signal into units of one or more bits and

replacing selected bits of said first signal with a corresponding number of said units of one or more bits of said second digital signal such that said first signal and said second signal are composited into a synchronized data stream.

13. The method of claim 12 for generating a synchronized signal wherein said first digital signal comprises samples of 24 bits, two of which bits are replaced by corresponding bits of said second digital signal.