I have heard about Lucent Technologies Perceptual Audio Coder (PAC). How does it compare to MPEG-2 AAC ?
AAC and PAC are similar audio coding technologies. However AAC has a number of new coding tools, such as Temporal Noise Shaping (TNS), that permits AAC to offer performance superior to that of PAC. This was shown in an independent and impartial test conducted by the Communications Research Centre (G. Soulodre, T. Grusec, M. Lavoie and L. Thibault, “Subjective Evaluation of State-of-the-Art 2-Channel Audio Codecs,” Journal of the Audio Engineering Soc., Mar., 1998, pp. 164-177). This test showed that when coding stereo signals, the quality of AAC at 96 kb/s was comparable to the quality of PAC at 128 kb/s and that AAC at 128 kb/s was significantly better than PAC at 160 kb/s. There is another test, conducted by Moulton Laboratories, that claims to compare PAC and AAC. However the system claimed to be AAC was not the same coding system tested by the Communications Research Centre, and did not use a state-of-the-art AAC encoder. Therefore, the results of this test do not indicate the actu
