feat: cross-fade jump cuts

[WofWca]

This is a pretty big one, sounds hard to implement.

You might have watched some videos that use this effect. It's where there is a jump cut, but not a regular one when one clip is immediately replaced by another one, but where you can hear the very ending of the first sentence and the very start of the next one (like 0.2 seconds) at the same time. This is sort of like setting "margin" to a negative value.

I believe with this effect we can save some more time, or improve clarity of audio.

(I think I wrote this down somewhere, already?)
So, initially I thought that this cannot really be achieved, because you would have play back both the end of the silent part and the start of the new sounded part, so you wouldn't actually save any time. But, with the stretching algorithm, I think this can be done. That is, if we play the ending of the silent part and the start of the sounded part at a faster rate, and then slow them down and cross-fade.

!!Or rather, with the current stretching algorithm, just not speeding up the start of the silent part!!

Another way: playing a clone of the element to get the copy of audio from it: the same way we do with the "cloning" algorithm.

[t9999clint]

I would like a very similar feature actually, just not for audio.
When skipping segments it would look a lot better to have a 3-5 frame video crossfade between the segments that are being stitched together. This makes the video a lot less jarring when watching people moving around. I used to do this a lot manually when editing videos for people. It makes a big difference and would be pretty neat to have a extension kinda do this automatically for the twitch VODs I like to watch.
I have no idea if that's even possible to implement. Maybe even a quick and dirty method of grabbing the first frame of the next segment and just overlay it at increasing opacity over the video feed right before it skips to the next segment.

On the audio side...
A cross fade thing I would like would be for the audio to fade to silence right before the jump and then fade back in to normal volume right after. This would also be super nice for the non skipping, fast forward mode. When there's background music it starts to sound super weird when it's fast forwarded and is kinda distracting.
This in theory should be pretty simple to implement. (I'm not really a programmer, so I might just be talking out my ass here)

[WofWca]

@t9999clint
About video: very interesting idea. Though yeah, it's gonna be a bit hard to make sure it works on all sites properly.

About audio non-cross-fade: it's similar to #17 (and perhaps even a part of it). Though if the fade is long, you lose a bit of saved time...