Patent ID: 6845355

Claim:
A method of using a codebook of frame patterns identified by index numbers to code a voice signal by sampling the voice signal to obtain sample values, grouping the sample values into frames, predicting the sample values in each frame, taking differences between the sample values and the predicted sample values in each frame to obtain a differential frame, searching the codebook to find a frame pattern most closely matching the differential frame, and writing the index number of the most closely matching frame pattern in a memory device as a coded value of the frame, each frame including a predetermined number of consecutive sample values from a first sample value to a last sample value, each sample value except the last sample value having a next sample value in the frame, wherein predicting the sample values in each frame comprises the steps of: (a) predicting the first sample value in the frame from at least one sample value of an immediately preceding frame; and (b) using each predicted sample value in the frame, except the last sample value in the frame, in predicting the next sample value in the frame; wherein said step (a) predicts that the first sample value in the frame is equal to the last sample value of the immediately preceding frame, and said step (b) predicts that all sample values in the frame after the first sample value in the frame are equal to the first sample value in the frame.