In the second of this two-part series on drum editing in Reaper, we use SWS Extensions to fill gaps and stretch time.
In last month's Reaper workshop, we learned how to detect transients on drum tracks, and then quantised them to land on the grid. This process is great for keeping the drums to time, but it leaves us with a load of gaps that fall silent, so this month we're going to use SWS Extensions to fill and smooth out those gaps.
If you haven't already done so, you'll need to download the donationware SWS Extensions (which comes with a free PDF manual) from www.standingwaterstudios.com and follow the installation instructions. It's an easy process and well worth the trouble for all the great features that are included. In this tutorial, we'll be using the Fill Gaps feature, created by Adam Wathan, the purpose of which is fairly self-explanatory!
It's worth experimenting with these settings to see what works best for you.
If you want to use time-stretching for problem areas where simply filling the gaps and crossfading isn't enough, you can engage the 'Stretch if needed' tick-box and set the 'Maximum gap' setting to a value where time-stretching would engage. For instance, if you set this to 50ms, only the gaps that are larger than 50ms would be stretched. This dialogue also has a percentage parameter that limits the amount by which an item can be time-stretched. For example, if this value were set to 75 percent, the playback rate on an item would never go below .750. If there were a bigger gap to fill, the next item would just move back and crossfade to fill that gap. No further stretching would occur.
Just below that is the 'Preserve transient' tick-box. If this is ticked, Reaper will set aside a certain portion at the beginning of the item to 'preserve' as the transient. So if we set the Transient Length to 60ms, the first 60ms would not be time-stretched (just the section after). To move from the transient to the stretched piece, another crossfade would be inserted, and that length can be set using the 'Crossfade length' just below it. The purpose of preserving the transient is based on the idea that the transient is the most important and loudest part of any drum sound. Time-stretching causes sound degradation, so it's optimal to avoid the stretching of the actual transient. Note that all of this is happening only with the items that exceed the 'Maximum gap' we've set. Everything else is still being trimmed back and crossfaded to fill the gaps without time-stretching. I would recommend starting out without using any time-stretching and see if it's necessary for your performance.
There's also a unique option in the Fill Gaps dialogue box, labelled 'Mark possible artifacts'. This creates a new marker in your project for each area that may have issues or glitches worth zooming in closer to examine. Sometimes a little manual trimming will be necessary with a few of the edits. I'd suggest listening to the whole piece with the drums solo'ed to double-check your work.