Optimal wordlength determination of AC-3 decoding hardware based on fixed-point analysis and simulations of AC-3 algorithm

In this paper, we perform a fixed-point analysis for Dolby AC-3 audio decoding algorighm, and determine the suitable multiplier wordlength (say, N) satisfying the required sound quality. After that, based on the similar simulations, we try to reduce the accumulator wordlength from the usual (8 + 2N) to (g + N + r) where g is the wordlength for overflow guard bits and r is the wordlength for rounding with the condition r < N. To show that r bit rounding is enough, error signal waveforms are shown which are obtained by subtracting the floating-point simulation generated PCM samples from the r bit rounded fixed-point simulation generated PCM samples. In addition to them, frequency magnitude plots of the decoded PCM samples are shown, and compared with those of the floating-point decoded PCM samples.