When Percussion Protection is and is not used...

[Steve Crook]

I've noticed a few occasions where PP is applied to one track and not to the other even though a very similar wave form gets de-clicked.

I'm cleaning with PP set to max, BP on and de-click at level 3.

I've no idea which is correct and which isn't, but given the similarity of the wave forms I got curious about the criteria for the decisions being made in the software over what's considered to be percussion and what isn't. If you have time, I'd be interested to know more, so I can understand how these edge cases arise. Just curiosity you understand.

In the sample I've attached, you can see the correction and the PP region, they're about 122 samples at 192kHz, so still a very transient event.

[Paul Sanders (AlpineSoft)]

Hi Steve,

There's really no such thing as 'correct' where click scanning is concerned.  Everything you see is VinylStudio's best guess, and relatively minor differences in the waveform can affect the decision it comes to in any particular instance.  The waveform display is there to keep you informed, and you can make manual adjustments or rescan with different settings if you choose.  Depends how much work you want to do.

[Steve Crook]

Yes, I wasn't concerned particularly, just interested. There are always edge cases that push hard at an algorithm and nothing is going to make a perfect decision in these cases.

It was only curiosity, particularly when I'd got PP up to maximum. But as you say, there's always the opportunity to hand edit. Honestly, life is too short, and even for a 120 sample correction I'm never going to hear it.

On a somewhat related note, I was looking for information on noise cancelling headphones and followed some links then fell over this paper (pdf) on using interpolation algorithms for noise reduction on LPs. Interestingly, the authors have also looked at using  neural networks (pdf) for noise removal.

I wasn't sure if this was something that might interest you or not. The maths has already hurt my head.

[Paul Sanders (AlpineSoft)]

Thanks, I'll take a look, but it's probably beyond me too...