cleaning vinyl audio?
Reply #38 – 2009-02-27 15:27:35
Hi GlaMas, Just got your PM. I didn't receive any email notification of your original posts, hence no reply. Sorry about that. I do indeed find your comments valuable, thank you for taking the time to post them. I can see it would be useful to be able to listen to the residual. I will put it on the todo list, it would not be hard to do. I have not looked into what can be achieved, manually or automatically, with a spectrogram but one problem I forsee is that VinylStudio needs to know *exactly* where a click is in order to repair it, which is why we scan for them in the time domain. But it's not an area I know much about so I will look into this in more detail when I have time. With regard to false positives and false negatives when scanning for clicks, *all* programs suffer from this to a greater or lesser extent. With VinylStudio, you can see them in the Corrections List which perhaps makes them more obvious. To compare like-for-like, you might like to import the results of a scan in WaveRepair into VinylStudio's list of Recorded / Imported files in the Cleanup Audio window for the album in question. You can then flip backwards and forwards between the two files and if you are luccky the waveforms will line up exactly. If so, you can then compare (visually) the output from VinylStudio with the output from WaveRepair. I think you might be surprised at what you find. I'd also be interested in your results for Jazz and Rock albums. The problem is always percussion, which is why classical music cleans up so well. I have experimented with various algorithms for differentiating a percussion burst from a click, and it always comes down to a compromise between false positives and false negatives. My goal has been to to make VinylStudio's declicker's settings easy enough to use that non-technical users can get decent results. Did you experiment with the PP (persussion protection) setting? Turning this up eliminates a lot of false positives, and one can subsequently deal with any false negatives by rescanning the affected section(s) with more aggressive settings. I am ashamed to admit that we default to a fairly low PP setting because it's what our target market seems to expect. With regard to hiss, hum and rumble filtering, the hiss filter (which is a broadband noise filter) is not a good choice for removing hum as you will lose bass notes if you fail to turn the hum filter on. This is because the hum filter is a narrowband 50 (or 60) Hz notch filter whereas the hiss filter works over a broader frequency range. By enabling the hum filter, you remove the hum from the 'noise print' used by the hiss filter, which in turn reduces the impact on bass notes in general. Again, we have focussed on ease of use in terms of the filter settings we offer. Why does the fact that VinylStudio knocks a few ms off the end of the file make it impossible for you to evaluate the efficacy of the noise filters?