I've been looking at the frequency response of the "rate -vMb 90.7" and "rate -vMab 90.7" filters. To do this I generated white noise samples in Audacity, upsampled them, and then looked at the FFT spectrum.
The "rate -vMb 90.7" filter attenuates to zero before the Nyquist frequency. i.e. before 22.05kHz for 44.1k audio. The "rate -vMab 90.7" filter attenuates to zero at around 24kHz. i.e. Higher than the Nyquist frequency, but much lower than the available 44.1kHz. I'd like to try a much slower roll-off such as that used by 'Ayre' (http://www.ayre.com/pdf/Ayre_MP_White_Paper.pdf) in their latest minimum phase "Listen" filter, but there appears to be no way to extend the frequency range of the filter. Any ideas where these parameters might be in the (commentless) sox rate code? -- VirusKiller ------------------------------------------------------------------------ VirusKiller's Profile: http://forums.slimdevices.com/member.php?userid=19799 View this thread: http://forums.slimdevices.com/showthread.php?t=69454 _______________________________________________ ripping mailing list [email protected] http://lists.slimdevices.com/mailman/listinfo/ripping
