Bit-depth expansion of digital audio is essential for enhancing the quality of digital contents in re-mastering and up-conversion processes. The current study predicts the least significant bits for the bit-depth expansion from upper bits in linearly quantized samples of a framed audio waveform. A simulated annealing technique is applied to minimize the effective power of the residual signal derived from linear prediction of the framed waveform by localizing positions of the least significant bit (LSB) to be added in the frame. The results of computer simulation using various genres of 100 mono and 10-s music signals exhibit that the mean correct rate of the predicted LSB is 72% using 8-bit quantized waveforms. Measurements of the objective sound quality degradation reveal that the mean objective difference grade (ODG) of the 8-bit signals improved from -2.96 to -2.56 after addition of the predicted LSB.
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