The health check that Tdarr can do depend on what health check you select, the “quick” health check will only check the file headers. This probably won’t find any video corruption unless the file headers are corrupted or invalid.
The thourough health check will basically do a transcode of the input file without an output. This is being used to run and check each single frame of the file and “process” it without actually producing an output. https://trac.ffmpeg.org/wiki/Null
Would this screw with plexs own traditional transcoding?
No, Plex and Tdarr are two completely different things.
Transcoding is not some universal thing but rather a term to describe what is happening. In general “transcoding” means that you convert something from one format into another.
When you use the processing pipeline through Tdarr, it would detect a file in your library and run it through your specified pipeline. Depending on what you want to do with the file and how the pipeline is configured, it might or might not do anything with that specific file. When you, for example, configure that you want any file that has a video stream that isn’t encoded with HEVC to be HEVC then a H.264 file would then be transcoded.
This is on a “replacement” bases, so any file you run through this would replace the existing file in your library. Meaning: you have a H.264 file before tdarrs processing and after it is finished, you have the file with HEVC as video stream.
With the health check, as explained above, this is a bit different since you don’t have an ouput file, there is also no replacement happening. It is just a “check” that the file can be transcoded in its entirety (with a thourough health check).
When Plex transcodes something, this is done “on the fly”. This means that it only transcodes the current file in your library.
Technically, tdarr could “screw” with the Plex transcoder when Tdarr processes a file while you yourself watch the same file that is then transcoded by plex. When Tdarr is finished, it would replace the file which then could throw off the Plex transcoder. But this is very rare or non existent and you could even configure tdarr to do those things only at a certain time and it wouldn’t happen with health checks. as someone who runs both, I have yet to come across something like this.
Or does it attempt to repair a file by transcoding
As the name suggests, health checks are only “checking” if the file is healthy, there is nothing being repaired here. While you might be able to repair the file header, a corrupted video or audio is not something you can repair because of missing information. But that is nothing that Tdarr will do anyway, it just verifies/checks if it is healthy or not.
Short answer: Because their motivation is to win!
I read something about this in the Book “Introduction to Game Design, Prototyping, and Development: From Concept to Playable Game With Unity and C#” by Jeremy Gibson a while ago, maybe that can explain this a bit.
Basically, every Player has some Intention or the “Player Intent” which is described by the Personality Types of Richard Bartle. For example, you have:
And then you have two others that you will be encountering:
So, the motivation to “cheat” could either be that this player doesn’t really care about the game, is able to get away with cheating and just wants to beat the game. According to Jeremy Gibson, a cheater might not cheat if they can win legitimately but I would argue that cheaters are usually not great players in the first place so the bar would be pretty low for them to “win legitimately”.
As for the spoilsport, this is extremely hard to work against or prevent because the motivation isn’t about the game anymore but other players, to make their experience miserable so that the spoilsport can gain satisfaction from it. Hence also the use of “don’t feed the trolls”.
With that being said, when you ask why someone would cheat, the question would rather be “What is their motivation” and the answer to that is “to win the game, at all costs”. And, most of the time, they will get away with this because they apparently cannot be caught as quickly as they can still continue doing it, if there is any action against them at all.