Short summary, about what I know (which means, some facts are missing or probably not true):
There does exist interest in PSX tasing as seen in these threads
1
2
3
4
5
6
7
so you are not the first one who asks for it. There are basically just too many difficulties (like not being open source), which prevented us of having a rerecording PSX emulator.
As far as I know, there are 3 emulators worth mentioning:
-epsxe: Probably the best known and most used one. However it is closed source, which will unlikely change, as there worked to many people on the project to allow the few currently working on it to make it open source.
-PCSX: This one is open source, which is the reason, why DeHackEd and valarnin already tried to
modify it. However, there seems to be a
general savestate bug, which couldn't be solved yet.
Recently, mz also
works on it with some successful results (
1,
2,
3), but it is still very experimental.
-
pSX: A closed source emulator, pSX author alone is working on. As he is generally over flooded with requests and advises, he also rejected bisqwit's and others proposal of helping with their experience of implementing rerecord features, which led to a slightly tensed atmosphere. He still plans on adding this feature, but firstly, we will have to wait some time, due to its low priority and secondly the lack of open source limits the usefulness for tasvideos a lot.
Yet, bisqwit managed to bypass these problems and created the first (and seemingly unnoticed)
PSX tas, using a different recording approach (directly recording an AVI), which however, also doesn't meet the requirements for a emulator that the while community can use.