.ap files - What are they and how do I use them?

[haddock1000]

!!!WARNING!!! I've been notified that ap files are not always working as described here. Please take this post with a very large heap of salt until further notice.

.ap files - What are they and how do I use them?

There are a couple of additions to TS2014 that have not been seen before, and have not been publicised by RSC. Most of these changes are so small and insignificant, you won't see them. However, if you like delving into the asset and content folders of your TS2014 installation, then you will certainly see one, the .ap file, and they are certainly an improvement!

What is the .ap file?

The .ap file is actually just a .zip file. That's it! If you change the extension of a .ap file to a .zip file, then windows will simply open it up, and allow you to access the contents. There is no encryption, no protection. All it does is holds a set of files under one name.

Why has RSC introduced the .ap file?

By packaging up assets and content into one .ap file, a number of advantages are realised.
1.) Disk usage. If you write a file to your HDD, it'll also occupy slightly more space than the file needs. This is the 'overhead.' Each file will have a slightly different amount of overhead, but in some cases that overhead can be massive, compared to the size of a file. For example, a 1kB file will actually take up 64kB of space! Multiply up such potential wasted space to the amount of files in your TS2014 installation, and you soon have a very inefficiently used HDD. By using the .ap file, this wasted space will be vastly reduced, because of less overheads.
2.) Steam verification. The way that steam verifies your TS2014 installation is by generating a checksum for each file. This is essentially a number that is created by performing a mathematical calculation to all of the 1s and 0s that make up the file. The same is done on the steam server. The numbers are compared, and if they don't match, then the file will be re-downloaded. This means that when you verify your TS2014 installation, it has to generate a number for each file, and compare it to the number stored on the steam server. However, with the .ap file system, steam views the zipped up files as one, and only generates one number, and only has to compare it to the steam server's number once, thus reducing the time that it takes to verify your TS2014 installation. The downside, however, is that if the file does get corrupted, it will download the whole package (but don't worry, you won't be modifying .ap files, see below.)

AAH! That means that if RSC gets things wrong, or I want to modify a file, the process is even more difficult!

Well that's where you are wrong! The process is actually much easier. This is because if a file is both held in a .ap file, and stored in the folder structure, the file in the folder structure will take precedence, or in other words override the file stored in the .ap file. Also, because seam does not care about files other than the .ap file, it will not remove any files that are overriding the .ap file. Lets explore an example.

Say for argument's sake RSC release a loco and the maximum speed that it can attain is not to your liking. You go into the .ap file and find the offending file. Now instead of extracting the entire contents of the .ap file, you just duplicate the offending file, and the folders that it is stored in. You modify the file to your liking, and load up TS2014. Because your modified file is outside the .ap file, two things happen
1.) Steam looks at the .ap file (if you do a verify of your TS2014 installation) and sees no difference to the copy stored on the steam servers
2.) TS2014 overrides the .ap file contents with the files that you have duplicated outside the .ap file and modified.

The downside to all of this is that if you modify something, a steam verify won't fix it.

Can I make my own .ap files?

Yes. When you have finished creating some assets or content, just zip the files up, change the extension from .zip to .ap and bob's your auntie (The only catch is that sometimes the windows explorer zip utility doesn't work for me for some reason. However, other 3rd party compression programs do seem to work).

Can I have more than one .ap file in the same folder? Which has priority?

You can have more than one .ap file in the same folder. All of the .ap files will have their contents loaded. I'm not sure which .ap file will have priority, all I know is that files outside .ap files have priority.

Do the .ap files fix the bloated product folder problem?

No. The blueprints are all still loaded, and bloated product folders will still be a problem.

Can I edit routes that are packaged up in .ap files?

No. If you want to edit a route, you will have to extract the .ap files.

I hope this clears up a few questions,

haddock1000