Work on this was prompted by me failing to find a plugin component that could be used by my favourite sound recorder as a filter to remove pops and crackles, or a plugin for a player to filter the pops in real time during playback.
The work has involved a steep learning curve with Apple's AVAudioEngine. The documentation is far from thorough and there's very little sample code around. That has not been fun but learning more about sound processing (DSP) and getting hands-on with some C++ really has been enjoyable.
We now have a standalone app that will open a sound file, apply pop filtering (pretty quickly - currently <6s for a 4 minute track, but I hope to significantly improve this).
The pop filter is applied, along with EQ and normalisation. For some reason, LPs seem to vary quite widely in sound (I think this is a different thing from playback equalization curves for early LPs and 78s.) Either way we intend that the graphic EQ in Vinyl Shine be flexible enough to handle all of this.
Options are minimal. A commercial app I currently use for pop filtering works ok but the result isn't perfect and it offers a shedload of options. What do those options mean? What am I supposed to change? Surely a pop is a pop, identify and remove it. Fewer options is the Mac way.
Vinyl Shine allows you to listen to the result and toggle between original and cleaned audio. And save the result as a new file when you're happy. (The final offline render is very quick, ~3s for a 4m song).
For the time being it currently exists as a standalone app and is working pretty well, making crackly recording much more listenable. It'll shortly be available as a free beta.
|pops, clicks and crackles are identified, highlighted visually and repaired|