| 摘要 |
<p>An audio peak limiter suitable for use between a compressor (110) and pre-emphasis circuit. The limiter uses a center clipper (130) to develop a control signal for a 1/x control law VCA (240). The center clipping, after rectification (170), is sampled-and-held for 4 milliseconds by a retriggerable sample-and-hold circuit (190) then low-pass filtered (210). The compressed audio is delayed for 4 milliseconds (220) before being coupled to the VCA (240). The VCA acts as a modulator to provide control of its peak output level while simultaneously limiting the bandwidth of the modulation sidebands caused by the modulation process, so that these sidebands are better masked psychoacoustically than sidebands that would be caused by simple clipping of the compressed audio.</p> |
