Pseudo-constant bit rate video coding with quantization parameter adjustment
US5241383A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 13, 1992 |
| Grant date | Aug 31, 1993 |
| Priority date | — |
| Expiry date | May 13, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N19/146
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method for coding frames of video wherein a coding circuit (14,16,18) includes a processor (30) for performing an orthogonal transform such as a discrete cosine transform and a quantizer (32) for quantizing the resulting transform coefficients. The coding circuit codes the video frames using intra-frame, predictive or interpolative coding to generate code bits at a variable rate. The code bits are stored at a variable rate in a rate buffer (22), which transmits the code bits into a communication channel (24) at a pseudo-constant rate, i.e. a rate which is constant in every time interval of one frame. To maintain the contents of the rate buffer (22) within predetermined limits, the quantization parameters utilized by the quantizer (32) are periodically adjusted to increase or decrease the amount of code bits generated by the coding circuit. The quantization parameters are changed on a global SGOP level to avoid changes of quantization parameters and corresponding changes in decoded image quality within particular frames. The change in quantization parameters for coding the next SGOP is determined by a deviation measure between the actual number of code bits generated by the coding…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.