# US 5,351,092 A · Synchronization of digital audio with digital video

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- Number: US 5,351,092 A
- Document ID: US5351092A
- Status: Granted
- Kind: A
- Application number: 08/096,356
- Filed: 1993-07-23
- Granted: 1994-09-27
- Earliest claimed: 1993-07-23
- Assignees: The Grass Valley Group, Inc.
- Inventors: Michael Poimboeuf; Kevin D. Windrem
- Web page: https://patentgrep.com/patent/US5351092A

## CPC

- H04N 5/95: Time-base error compensation {(H04N5/932 takes precedence)}
- G11B 27/10: Indexing; Addressing; Timing or synchronising; Measuring tape travel
- H04N 5/04: Synchronising (for television systems using pulse code modulation H04N7/56)
- H04N 9/802: involving processing of the sound signal (H04N9/806, H04N9/835 take precedence)
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)

## Abstract

A method for synchronization of a digital audio signal sampled at a standard audio frequency with the corresponding digital video signal sampled at a standard video frequency associates an integer number of samples of the digital audio signal with each video field of the digital video signal. The number of audio samples per video field is determined by the audio sample rate rounded up to the nearest integer. Every N video fields where the number of digital audio samples is an integer value, the digital audio signal is resynchronized with the digital video signal by repeating the digital audio samples at the end of video field N that correspond to video field N+1. At reception the same digital audio samples are skipped at the end of video field N.

## Claims

### Claim 1

A method of synchronizing a digital audio signal with a corresponding digital video signal comprising the steps of:
associating for transmission an integer number of samples of the digital audio signal obtained at an audio sample rate with each video field of the digital video signal, the number of digital audio samples per video field being determined by the audio sample rate and duration of each video field rounded up to the nearest integer; and
for each N video fields, where N is the number of video fields for which there is an integer number of digital audio samples as a function of the audio sample rate, resynchronizing the digital audio signal with the digital video signal by repeating the digital audio samples at the end of the Nth video field that correspond to the digital audio samples at the beginning of the N+1st video field.

### Claim 2

A method as recited in claim I further comprising the steps of skipping for reception the digital audio samples at the end of the Nth video field that correspond to the digital audio samples at the beginning of the N+1st video field.

### Claim 3

An apparatus for synchronizing a digital audio signal with a corresponding digital video signal comprising:
means for associating for transmission an integer number of samples of the digital audio signal obtained at an audio sample rate with each video field of the digital video signal, the number of digital audio samples per video field being determined by the audio sample rate and duration of each video field rounded up to the nearest integer; and
for each N video fields, where N is the number of video fields for which there is an integer number of digital audio samples as a function of the audio sample rate, means for resynchronizing the digital audio signal with the digital video signal by repeating the digital audio samples at the end of the Nth video field that correspond to the digital audio samples at the beginning of the N+1st video field.

### Claim 4 (depends on 3)

An apparatus as recited in claim 3 further comprising means for skipping for reception the digital audio samples at the end of the Nth video field that correspond to the digital audio samples at the beginning of the N+1st video field.