@corpseil Hi. Unfortunately we’ve found an entirely different picture ever since that thread.
First of there were nasty sound issues that have been fixed one after the other ever since, however similar to other animation software Pencil2D image playback will lag against the sound the more frames and layers you have.
This happens to me with Flash (animate CC), with Toonboom Harmony and even with After Effects. The difference is that other apps have a “preview” feature built-in. Pencil2D currently does not have this, and while it is on the roadmap it will take time to be implemented.
Just as an example I used all three choices I’ve mentioned and I always, always have to pre-render or “cache bake” the playback to play it back as a video, this is basically dumping everything to memory and otherwise I can’t see the real time playback. Flash and AE show frame drops when doing real time playback due to the sheer amount of layers and frames I work with, while Harmony becomes slow as heck with a plethora of deformers, it’s unfortunately normal.
Of course this has nothing to do with having a monster PC or, it’s about a basic impossibility of having dozens of images preloaded in memory along sound without some form of compression.
Video editors do this right, don’t know the technicalities, but my guess is that they do the same as the preview features in other apps, which is to “flatten” or “compress” everything into a playable format to play it back at the target speed. It’s always easier to play a single stream of images and audio than a dozen of them.
Anyway right now the only way to accurately listen to the sound against the image is to use the audio scrubbing feature. When you’re doing lip-sync and looking for the beats this feature is invaluable, other than that accurate real time playback is currently not possible just yet.