Re: [Audacity-devel] Noise Reduction

[Bill W. <bi...@go...>]

“Noise Removal” is broken. It has been broken since at least 2009.

http://wiki.audacityteam.org/wiki/Proposal_Noise_Removal#The_big_problem

One of the major improvements in Noise Reduction over Noise Removal is that the "big problem" was fixed.

Some (very few?) users have reported that they got “better results” with old effect. As Paul points out, we don’t really know how or why, and we don’t know what they mean by “better”. I’d speculate that the old effect did no NR in the presence of signal, and so was less likely to damage the signal. The old effect was much more prone to “tinkley bells”.

Frequency smoothing was added, IMO, as a kludge to deal with the tinkley bells, when what should have been done is fix the “big problem” (as well as the discrimination problem, which was also addressed in the new effect).

For my use case (cleaning up vinyl captures) I don’t want any frequency smoothing. I can demonstrate that it damages the signal. I’d prefer to leave the default frequency smoothing at 0 since that is the safest option. We’re talking about using frequency smoothing to solve an ill-defined problem when we don’t even know if frequency smoothing is solving the underlying problem or just making it less audible (and causing collateral damage to the signal).

I don’t think we should cater to users who won’t take advice to adjust settings to find the best ones for their situation.

— Bill

On 2015/05/30, at 8:13 AM, Paul L <pau...@au...> wrote:

> I can't promise anything when "good results" are all in the judgments of
> users who are making complaints but providing no specifics.  Should we
> assume these are all impatient users who never try any variations from
> default settings, since they make no mention of settings?
> 
> I only have a sample of one to go on, in which a dissatisfied user shared
> some of the audio they were trying to treat, and I expressed my opinion that
> greater Frequency Smoothing than default was all that was needed.  But I did
> not hear back again whether this suggestion satisfied them.
> 
> I hope you meant that it is the old Noise Removal that would be present, but
> hidden by default.  I don't like this admission of defeat, but if there is
> demand for that, do it.
> 
> Both of these effects could in principle be rewritten as Nyquist plug-ins,
> down to the least details, so neither would really need to be built in, but
> I never got around to that academic exercise.
> 
> 
> James Crook wrote
>> Paul,
>> 
>> Could you do some work on Noise Reduction to make it as easy to get good 
>> results as it was for Noise Removal?
>> It may be a question of default settings.
>> 
>> Now that we can reduce the effects menu, do you think it would be a good 
>> idea to include both Noise Reduction and Noise Removal as effects?  Or 
>> include Noise Reduction, but hidden by default?
>> 
>> [If there is lots of argument about that and no clear consensus, I will 
>> make the decision]
>> 
>> --James.
>> 
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