"you mentioned xtool does auto detection on the first stream. Does it iterate through all 81 levels until match is found, or only few known to be used most often?"
- it does for all streams, all 81 options but very quickly, takes milliseconds per stream to go through all 81 options.
"It don't need to go through all 81 every time"
- it doesn't go through all 81, sometimes even the first option it tries is correct and it stops, if it isn't correct then the 2nd one is most likely correct because of stats. XTool requests mode (value that appears most often), if that option fails, it requests mode in 2nd order (value that appears the 2nd most often) and so forth... which is why trials on all streams is necessary because it keeps the stats function filled with updated information about the current input.
"next stream can be tested with that level found in previous stream first."
- this method is the same as stat but it stores information limited to one stream which happens to be the previous stream, the approach of xtool is it stores a number of previous stream information, default is 256 streams.
Let's say for example
if the first stream was gave back level 9, the next stream is determined to be level 9, roughly the same as what you suggested, but what if the third stream is level 6? you have go through all the trials, ok fine, now you think then next stream is level 6 because of previous stream but what if that level 6 stream was just png image within the game data but instead the entire game was level 9? you try level 6 on the next stream it fails, then again you have to go through all 81 options again. XTool apporach thanks to stats, is level 9, level 9 and level 6 is what was stored, so for the next stream, it doesn't matter if the last one was level 6, it will try level 9 because it was detected twice compared to level 6, if it wasn't level 9, it will try that level 6 before it tries all 81 options because it was at least detected once, if that fails. it then tries 81 - 2 (6-9 from stats already failed) it does this for the past 256 streams and tries options in mode orders.
"I have never noticed ztool/xtool being slow at beginning, it seems to start immediately"
- It's because of stats plus other methods I've developed that make this possible.
"Perhaps up to few seconds of delay should not be much problem in scope of thousand streams and GB's of data?"
You'll notice not just "few seconds of delay", yes few seconds for a set of streams but minutes of overall delay
if you were to use this method for big streams, try this on dirt rally or doom 2016 and you'll see some incredibly low CPU utilization when using a lot of threads because other threads are obliged to wait for the first stream.
"As for MT, that's not a big deal we don't want to test whole data only first couple of streams(again assuming it should not take long)."
with large streams, it is guaranteed to take long as mentioned before, which is why xtool faces too many problems with multi threading, I've instructed the threads to try 81 levels while using stats from all the streams they can find, as a result they end up fighting and crash each other
it's hilarious but you get the idea, it's just best to try all levels on all streams but let stats decide in what order they should be presented in to speed up the process.
"You mentioned using stats, that sounds actually very similar to what I am talking about."
- Yes with the exception that not the previous stream option is considered but the previous 256 stream options are considered. If from those 256 options, there are 128 level 6s, 10 level 3s , 1 level 5 and 20 level 9s, it will try them in the order: 6 >> 9 >> 3 >> 5, then since all that failed, it begins trials, 1 - 9, it will skip, 3,5,6 and 9 because those failed, after that the new discovered level is added to stats, if it was 2, it will try the new order as 6 >> 9 >> 3 >> 5 >> 2, the reason all streams have to try all options is to get rid of non appearing options, example is when the data out of nowhere started to become level 4 out of nowhere, as stats are added, the number of level 9s will decrease because of these new levels 4s until they reach a certain threshold, then the order will now be 4 >> 6 >> 9 >> 3 >> 5 >> 2, as you can see level 4 over took level 6 but level 6 is still considered because before all of the level 4s there were a lot of level 6s so yes, I really did think deep about how to speed up xtool
"I understand correctly you may have already implemented what I am talking about here"
- Yep
"So you in fact are collecting from multiple streams, not just first?"
- Yes, I had to carefully do this else the threads crash themselves while fighting for the same stream or the same information, causes headaches but I find it funny when this happens, this is what causes most problems in pzlib/ztool and old xtool but if you properly implement it, you get to enjoy all the speed that comes with it.