Re: [LAU] Rolling off high frequencies when mastering?

Speaking for Vorbis, it depends on the quality mode or bitrate you select. Vorbis is also fully aware ot the ATH and absolute dynamic depth of the human ear. If its psychoacoustics say a tone is inaudble, it won't code it. Energy is preserved, even at the exact nyquist frequency, however modulating the input signal against the sampling clock results in the signal being partly shifted to DC. The signal energy is there... it appears somewhere else. This is the case only with a signal exactly at Nyquist, unless you also have a system exhibiting IMD (most modern ADCs and DACs are very very clean. I can't measure the IMD even on my ten year old samplers, though they're much noisier than today's). The aliasing caused by signals exceeding the nyquist and folding back over into the sampled spectrum as well as aliasing caused by IMD at or near the sampling frequency are both mitigated/practically eliminated by lowpassing somewhere south of Nyquist. This is utter hogwash. All the signal energy and resolution is preserved to exactly the limits of the sampling rate at all lower frequencies, even if your 'biggest dots' aren't landing at 0dB or wherever. True of audio signals, true of images, true of video. The same discrete sampling lessons apply to all three equally. Monty