Rerecording Feature

[ZeXr0]

I see a lot of interest in implementing rerecording feature. The people at tasvideos.org would really like to have an emulator to do time attack of speed run. It is tool assisted video that push the game's to the limit. It is really interresting to see those movie.

Anyway it would be nice to have such feature, that allow to record frame by frame button press on a savestate I think. That wait it can be replayed from the emulator with a cd, without having to actually play it. It it's done well, you could see the game as if someone is playing it from the emulator.

There's more information on tasvideos.org, and it would be a nice boost to this communauty if it was the first emulator to actually do it.

[Sotho Tal Ker]

Shouldn't that be in one of those threads for requesting stuff for the next version?

Right now, not even normal recording is implemented.

And there are some problems with that because of the async CD reads pSX uses. (But which also means it does not suffer from some glitches other playstation emulators have

[patrickp]

I think it has already been mentioned there, Sotho, but if zexr0 wants to try and get a discussion going on/raise some interest in rerecording, why not? This is a forum, and he sees this topic as having relevance to the development of the emulator.

[Sotho Tal Ker]

I only asked if it wasn't better there.

Why not just let people post what they think how it should work? (And different methods on how to implement any future rerecording stuff)

So everyone who has an idea, jump in and explain what you think: How should it work, what is important and so on.

[Ultima]

Recording video means either recording raw, or including some kind of video compression, the latter of which sounds rather... extraneous to me, and the former taking up too much space. As for recording key strokes... I've always had my qualms about how accurate it might be for some odd reason or another (I know it works fine on the SNES/NES/whatever emulator, but even still...).

[Sotho Tal Ker]

The problem with recording directly to a movie is that you cannot be very accurate. Especially when it comes to rerecording, there will be a loss everytime you load from a state save again, because it is very unlikely to hit a keyframe.

The best would be to record inputs for every frame and then play them back in the emulator. This should also keep the filesize down.
Rerecording could then be easy achieved if information about where in the recording file to start again. This together with a "advance one frame" feature should make a quite good rerecording feature.
If you want it to be in video file format you could still use a screen recorder

[ZeXr0]

Okay first you don't need a recording feature to implement rerecording, it is a way to record what input are in the emulator frame by frame. So when you replay that sequence of input, it will be the same exact game that you will have played because RNG number changes with a lot of things but it is based on the game and not like a computer with the time from 00-01-01.

Based on that, when you are able to have every input frame by frame, without any frame skipping, you can watch the game just like someone else is playing in front of you. Then after you have that, you can try implementing the recording of an AVI, normaly in the emulator I think there is no compression on the movie, so I makes a big AVI, that other people compress with their computer but then it is often bisqwit that makes the movie.

All you need to have for this (and it would be a great help to tas maker) :

Record the input of the emulator frame by frame
Being able to replay that sequence
It should be recorded from frame 0 : console power on
You can resume the recording of a movie from a save state (doing this erase every later input and keeps only what's is before the savestate)
You need to be able to slow down the speed (like playing a game a 3% 6% 10% 50% etc..)
and you need to be able to advance frame by frame (with a selected key).

if you have any question, please try to quote something I wrote and I'll try to clarify this for you.
And feel free to ask a lot of question

[piratesephiroth]

OK, my first post.
Anyway, waht happened? I don't see pSX Author's comments anywhere...
Maybe you're not aware of that, but we're not trolling or anything.
The TAS community grows at a reasonable rate, and so does the quality of the published videos, making it more popular and attracting more talented people and so on... The coders work hard modifying the available open source emulators to implement the re-recording features.
When we came to know pSX, we soon realized it had potential to become a great emulator. Of course, someone came down here and started discussing the subject.
It seems no result was achieved...
Whatever... attention was driven to PCSX, the only open source psx emulator.
Some progress was made (it records/replays most games we tested without desyncs, but it's not re-recording). And it ended there, because there's a nasty bug in the savestates and there's no expert in psx emulation there.

There are re-recording emulators for all the popular legacy gaming systems, EXCEPT the Playstation... and there are so many interesting games to work on...

So what does "his highness" think?

[Deleted]

Author recently mentioned that he is working on recording functionality, so keeping that in mind I wouldn't rule re-recording out.

However, if it ever comes, I doubt it will take preference over compatibility improvements.

So who knows if and when it might happen.

[patrickp]

There has been a recent thread in which this was mentioned, piratesephiroth, and in which pSX Author said he would be including movie recording - not re-recording - in the next version of pSX.

However, re-recording - or input recording - is mentioned there, and it's pointed out that in many games, battles are more or less random, both in encountering enemies and in the progress of the battle. How does re-recording handle this?

Might be a good idea to respond in that thread - that's the one that has the attention ATM.

[amaurea]

The short answer is that those battles aren't random - nothing in the game is. If it were, that would be an encapsulation problem for the emulator, as it would mean that the outside environment is affecting the emulated machine in other ways than through the inputs. Randomness does not just appear in a closed system. You need a source of randomness, and in a properly encapsulated emulator, the only source is the input.

See the other thread for a longer answer. Anyway, rerecording emulators exist and are being used, so this is known to work. We just don't have a good rerecording playstation emulator yet.

[piratesephiroth]

hmm... the other topic is called "great emulator", those messages are in the wrong place... let's discuss re-recording here.

Here is an example. It was played in realtime (with savestates) and recorded with FRAPS. In a re-recording emulator, I guess I could do it in 29, maybe 28 seconds.

[patrickp]

Yes, but most of the discussion has already taken place in the other thread, piratesephiroth; posting here is only going to split responses. If necessary, I'll lock this thread.

Why don't you ask kevkid (OP in the other thread) if he fancies changing its name - it wasn't anything special, anyway?

[piratesephiroth]

ok. movin on

[patrickp]