Method and apparatus for nesting secondary signals within a television signal
US5808689A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 5, 1995 |
| Grant date | Sep 15, 1998 |
| Priority date | — |
| Expiry date | Sep 5, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/802
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus is disclosed for encoding secondary signals, such as audio signals, within a television signal in a manner such that the signal may be either recorded on a video cassette or broadcast. The audio samples are encoded only on selected lines of each video frame which do not interfere with dedicated broadcast and cable lines and are not affected by head switching of a video cassette recorder. The audio samples are encoded only within an overscan portion of the selected lines such that the encoded samples do not interfere with other portions of the video signal. However, by encoding the samples within the overscan portion, the samples do not affect the displayed image. The secondary audio signal is sampled during equally spaced intervals throughout the video frame, then compressed and encoded only within selected horizontal lines. During decoding, the audio samples are decompressed and played back at the original sampling rate to provide audio playback.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.