Why is MPC perceived to be the best?
Reply #21 – 2004-02-10 00:16:58
We should start making some preparations for this test right away. It will be exceedingly time consuming to come up with settings for all these different encoders that all have the same nominal bitrates. I suggest, since we are mainly testing Musepack here to start at --quality 4, then go to --quality 4.1, --quality 4.2 etc, until we reach statistical transparency , so to speak, presumably somewhere between --quality 4 and 5. Finding equal nominal bitrates for all the encoders, should be easy at --quality 4, we already know the correct settings for 128kb/s nominal on most encoders, but trying to find these values for --quality 4.x (where x≠0) will probably be considerably more difficult. We will have to encode a LOT of samples to do this. While the above process would be very scientific in approach, the resulting number of test groups would be far more than (most) anyone would want to deal with, especially if the goal is to include similar tests for other codecs. You would run the very real risk of boring your test audience into giving up early, and initiating lisening fatigue that could skew the results. Keep things simple. I would wager most people use whole number 'quality' settings (where applicable) or other significant steps (like --alt-preset standard or extreme). To that end, these settings should be raised or lowered by these significant steps until transpareny is found or lost. It would be just as relevant to prove that, in general , transparency of a given codec occurs between 'quality' 4.0 and 5.0, and be far simpler to test. Future testing could isolate which particular setting is the threshold, if any single one exists. I agree with you in terms of tester fatigue/boredom. However I can already tell you the result of this test if we used integer values for --quality: --quality 4 = not transparent --quality 5 = transparent We certainly wouldn't find the exact point at which MPC becomes transparent, which ScorLibran origonally intended:Format............Perceptual Transparency Threshold (nominal bitrate across samples tested) MPC.................nnn kbps AAC.................nnn kbps Vorbis..............nnn kbps ...and so forth