Preview playback actual exported cuts

[mifi]

Pulled out from #253 - Currently it's possible to preview playback cut segments (according to start/end cutpoints in the original file). However as we all know, the actual cuts in the exported file will not always turn out the same. Currently the only way to preview it is to actually export and then look at the resulting video before adjusting and trying again. A workaround is to only enable one or two segments at a time to speed up the export/checking process. Then once a cutpoint looks good, then enable only the next segment (or two).

Potential solutions:

• Feed segments through ffmpeg (probably with -t in order to only render the beginning or end of each segment) and show to the user a preview of the output
• Implement a live-stream of the output cuts, ala MediaSource to present to the user when they press a special "play" button

Alternatively:

• Manually export the file, wait for the export to finish, and then load the exported file to play it back with its actual exported segments and use functions like "Loop beginning and end of current segment" Check merged cuts in exported file #1886 Advanced export dialogue option to auto load merged video with chapters to review cut points #622 (comment)

See also #253 #1756

[ceekei]

I manage this at the moment with a little spreadsheet but implementation in Losslesscut to jump to the cuts is highly appreciated!