Global rate control for model-assisted coding of low bit rate video
US5745178A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 22, 1996 |
| Grant date | Apr 28, 1998 |
| Priority date | — |
| Expiry date | Jan 22, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N19/20
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for coding an image comprising (at least) two regions (e.g., a facial region and a background region) which are to be coded with different quantization error parameters (e.g., quantizer step sizes), wherein the respective quantization error parameters are determined with use of a feed-forward rate control technique. Initial quantization error parameters are assigned to each region, and the overall bit rate which would result for the coding of the given frame is computed based on these assigned quantization error parameters. The computed bit rate is compared to a given bit rate constraint which may, for example, represent a limitation of a transmission channel. Based on the result of this comparison, one or both of the assigned quantization error parameters are adjusted, thereby resulting in different quantization error parameters for the two regions. For example, if the computed bit rate exceeds the given bit rate constraint, at least one of the quantization error parameters is advantageously adjusted in a direction which results in the use of fewer coding bits (e.g., a coarser quantization). If the given bit rate constraint exceeds the computed bit rate, at …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.