On Mon, Apr 20, 2015 at 8:59 PM, Claudio Freire <klaussfre...@gmail.com> wrote: > On Mon, Apr 20, 2015 at 8:32 PM, Andreas Cadhalpun > <andreas.cadhal...@googlemail.com> wrote: >>>>> The long version: >>>>> >>>>> ath should approximate the shape of the absolute hearing threshold, so >>>>> yes, it's best if it really uses the minimum, since that will prevent >>>>> clipping of the ath curve and result in a more accurate threshold >>>>> computation. >>>> >>>> So you agree with my patch fixing minath? >>>> Or would you prefer a version with: >>>> minath = ath(3410 - 0.733 * ATH_ADD, ATH_ADD) >>> >>> Well, that's not really closer to the minimum (a few tests with gnuplot >>> say). >> >> Are you sure your plots were done correctly? >> Because I'm quite sure this is the correct first order approximation >> of the minimum. >> >> For ATH_ADD = 4 this gives 3407.068, which is quite close to Michael's value >> (3407.080774800152). > > I checked the formula several times, but still, I could have made a mistake.
This is what I did if you want to check it out (maybe you spot the mistake) gnuplot> ath(f,a) = _ath(f/1000.0, a) gnuplot> _ath(f,a) = 3.64 * f**(-0.8) - 6.8 * exp(-0.6 * (f-3.4) * (f-3.4)) + 6.0 * exp(-0.15 * (f-8.7) * (f-8.7)) + (0.6 + 0.04 * a) * 0.001 * f * f * f gnuplot> plot [f=3400:3500] ath(f,4), ath(3410-0.733*4, 4) Funny thing, is it's much closer with: gnuplot> plot [f=3400:3500] ath(f,4), ath(3410+0.733*4, 4) _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
