| 摘要 |
A closed-loop, multimode, predictive speech coder includes a codec (100, 200) configured to operate in any of several coding modes, and a closed-loop mode decision module configured to apply a lowest-bit-rate coding mode to an input speech frame. A performance measure of the codec is obtained and compared with a threshold value. If the performance measure does not exceed the threshold value, the lowest-bit-rate coding mode is rejected in favor of a coding mode with a higher bit rate. The process can be continued until the coding performance is satisfactory. A higher-bit-rate, direct coding mode may be applied after a lower-bit-rate, prediction-based coding mode has failed to perform satisfactorily. |
