This ignores the first part of my response - if I, as a legitimate user, might get caught up in one of these trees, either by mistakenly approving a bot, or approving a user who approves a bot, and I risk losing my account if this happens, what is my incentive to approve anyone?

Additionally, let’s assume I’m a really dumb bot creator, and I keep all of my bots in the same tree. I don’t bother to maintain a few legitimate accounts, and I don’t bother to have random users approve some of the bots. If my entire tree gets nuked, it’s still only a few weeks until I’m back at full force.

With a very slightly smarter bot creator, you also won’t have a nice tree:

As a new user looking for an approver, how do I know I’m not requesting (or otherwise getting) approved by a bot? To appear legitimate, they would be incentivized to approve legitimate users, in addition to bots.

A reasonably intelligent bot creator would have several accounts they directly control and use legitimately (this keeps their foot in the door), would mix reaching out to random users for approval with having bots approve bots, and would approve legitimate users in addition to bots. The tree ends up as much more of a tangled graph.

This ignores the first part of my response - if I, as a legitimate user, might get caught up in one of these trees, either by mistakenly approving a bot, or approving a user who approves a bot, and I risk losing my account if this happens, what is my incentive to approve anyone?

Additionally, let’s assume I’m a really dumb bot creator, and I keep all of my bots in the same tree. I don’t bother to maintain a few legitimate accounts, and I don’t bother to have random users approve some of the bots. If my entire tree gets nuked, it’s still only a few weeks until I’m back at full force.

With a very slightly smarter bot creator, you also won’t have a nice tree:

As a new user looking for an approver, how do I know I’m not requesting (or otherwise getting) approved by a bot? To appear legitimate, they would be incentivized to approve legitimate users, in addition to bots.

A reasonably intelligent bot creator would have several accounts they directly control and use legitimately (this keeps their foot in the door), would mix reaching out to random users for approval with having bots approve bots, and would approve legitimate users in addition to bots. The tree ends up as much more of a tangled graph.

I think this would be too limiting for humans, and not effective for bots.

As a human, unless you know the person in real life, what’s the incentive to approve them, if there’s a chance you could be banned for their bad behavior?

As a bot creator, you can still achieve exponential growth - every time you create a new bot, you have a new approver, so you go from 1 -> 2 -> 4 -> 8. Even if, on average, you had to wait a week between approvals, in 25 weeks (less that half a year), you could have over 33 million accounts. Even if you play it safe, and don’t generate/approve the maximal accounts every week, you’d still have hundreds of thousands to millions in a matter of weeks.

If your drive is the bottleneck, this will make things worse. If you want to proceed:

You’re already using ffmpeg to get the sequence of frames, correct? You can add the -ss and -t flags to give a start time and a duration. Generate a list of offsets by dividing the length of video by the number of processes you want, and feed them through gnu parallel to your ffmpeg command.

My first thought was similar - there might be some hardware acceleration happening for the jpgs that isn’t for the other formats, resulting in a CPU bottleneck. A modern harddrive over USB3.0 should be capable of hundreds of megabits to several gigabits per second. It seems unlikely that’s your bottleneck (though you can feel free to share stats and correct the assumption if this is incorrect - if your pngs are in the 40 megabyte range, your 3.5 per second would be pretty taxing).

If you are seeing only 1 CPU core at 100%, perhaps you could split the video clip, and process multiple clips in parallel?