1. A decoding method for an audio video coding standard (AVS) system, for decoding encoded audio/video data, decoding method comprising: a) setting a stop-fetching flag to an enabled status or a disabled status according to at least one stop-fetching criterion, wherein the at least one stop-fetching criterion comprises: setting the stop-fetching flag to the disabled status when a remaining shift value obtained by subtracting a range shift value from the offset shift value is smaller than an upper limit of the remaining shift value; and setting the stop-fetching flag to the enabled status when the remaining shift value is greater than or equal to the upper limit of the remaining shift value; b) in an offset fetching procedure, determining whether a valid offset value is smaller than a threshold and whether the stop-fetching flag is in the disabled status; c) when a determination result of step (b) is affirmative, fetching a subsequent bit for the valid offset value, correspondingly increasing an offset shift value, and iterating step (b); d) when the determination result of step (b) is negative, terminating the offset fetching procedure; and e) after the offset fetching procedure is terminated, determining whether a decoding result is a least probable symbol (LPS) or a most probable symbol (MPS).