Video signal encoding
US4125861A · kind A · utility
29Cited by
8References
20Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Aug 18, 1977 |
| Grant date | Nov 14, 1978 |
| Priority date | — |
| Expiry date | Aug 18, 1997 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N19/593
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
When a video signal is encoded using differential pulse code modulation (DPCM) techniques, the frequency of occurrence of the various quantizer output or representative levels is non-uniform; usually, low levels occur more frequently than high levels, and this characteristic can be used to advantage by applying the DPCM output to a variable length encoder before transmission. The present invention increases this advantage by intentionally forcing the quantizer output to particular levels when doing so is not harmful to the picture fidelity. By so doing, the entropy of the encoded signal is reduced by as much as 25 percent.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.