This work presents a low-complexity MP3 algorithm over a fixed-point arithmetic. A new rate control is introduced for the MP3 encoding algorithm, rather than the rate control in ordinary MP3. The computational complexity of the rate control is reduced by taking the loop-independent components outside the loop and accelerating the nonuniform quantizer using a hybrid scheme. The hybrid scheme includes a lookup-table method for smaller numbers and a linear piecewise approximation for larger numbers. A precise method for predicting the quantizer parameter is developed to decrease the number of times the rate control is executed. A hybrid scheme is also used in MP3 decoding algorithm to accelerate the dequantization. However, the approximation for larger numbers is two-tier. The first tier is a linear piecewise approximation that yields a rough value. The second tier uses the rough value as the initial value of the first -order Newton's method to obtain a more closely-approximated value. The precise method for prediction has a statistically hit rate of 43%, and the new rate control consumes no more than 4.5 MIPS. The proposed dequantization consumes no more than 2.38 MIPS, and has an error-to-signal ratio of under 0.012%. The implementation of the complexity-reduced MP3 algorithm over 16bit fixed-point arithmetic is subjectively tested to evaluate the quality of the complexity-reduced MP3 algorithm.
- Fixed point
- Low complexity