my project last night involved concatting about 3000 video files together. Unsurprisingly, something went wrong, and I ended up with a 5 hour file (the clips added together are only 2hr30min) and it stops being playable after an hour
now, ffmpeg has three ways to combine video files together. In order of increasing speed and decreasing flexibility, they are: 1. concat 2. concat 3. concat
now all three concats work very differently and are invoked differently. (Never use #3 on mp4 files, it will corrupt them!)
my problem was that I was using concat when I should probably just use concat instead. the only problem is that concat (not concat) requires a filter-complex invocation that may literally involve sacred geometry
so I either need to switch to using concat only, or convert those files so that they can all use the same format and thus be concatted with concat (but not concat, because that will corrupt mp4 files)
actually now that I'm looking at this and it's not 4am, the first concat might not be that hard, assuming ffmpeg (and windows) don't have a problem with me writing, uh, 55kb arguments? not counting the other arguments, which'll add up to another 87kb
I'll batch it up. Merge a hundred videos into one lossless master, then merge one lossless master with 100 more videos into lossless master #2, then repeat until I run out of videos
but I'm probably going to reencode those 3 Weird Videos anyway just so I have more control over how they're added. one of them is 4:3, the rest are 16:9: clearly I should handle that myself and not just let ffmpeg pick some silly default for merging 4:3 content into a 16:9 stream