Conditional replenishment video encoder with sample grouping and more efficient line synchronization
US3962535A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 25, 1975 |
| Grant date | Jun 8, 1976 |
| Priority date | — |
| Expiry date | Apr 25, 1995 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N21/242
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A video sample is selected for transmission only if it differs significantly in amplitude from the sample corresponding to the same spatial point in a previous video frame. An address word which indicates by its value the position of a sample within a video line is transmitted prior to the amplitude of a sample only if the previous sample was not selected for transmission. The amplitudes for selected samples are transmitted in groups preceded by an address word and terminated by a flag word. Frame synchronization is maintained by transmitting a first sync word during the vertical blanking interval. Ordinarily, the first sample in a video line selected for transmission has an address which is lower in value than the address word of the previous sample selected for transmission and, therefore, no line synchronization is necessary. The number of video lines in which no samples are selected for transmission is determined by a counting circuit and this number is transmitted in the form of a sequence of bits following the address word of the first sample selected for transmission in a video line. A second sync word is selected for transmission during the horizontal blanking interval when…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.