I just ordered it yesterday. :P I'll let you know when it gets here.

In my experience Steam uses better compression than GOG on their downloads. At best they can shave off 50-70% of the DL size.

I presume you are not talking about downloading the GOG installers, as those seem very well compressed already.

If you mean only the Galaxy-integrated versions of games, I think earlier Galaxy didn't even use any compression there yet, not sure what is the current status for that. If you want to minimize the amount of data downloaded, I presume downloading the installers is the best way to go (and then import them into Galaxy, if you are so inclined).

Indeed. I don't really understand why Galaxy files aren't compressed, as the compression in Steam doesn't make getting in the game any slower after the DL is complete.

well, the download server are properly set up to support download resuming. So in theory you should be able to download the files in as many "portions" as needed. Just pause and resume ...
Not really even necessary to split the files at all.

To be honest, I don't know from personal experience. I was going by what I'd read from others here on the forums. So, if that information was wrong, I apologize. In fact, I have attempted to make the downloads via the client, but every time I tried, it failed the attempt after only about 1% completion. Don't know if it's just another flaw of our "beloved" (intense, venomous sarcasm) Windows 8.1, or if it's just a limitation of my local library's internet connection. Either way, it's a no-go for me.

You have no friends who could download the games for you and give them to you? If they don't have limited access to internet.
Ah but i also used the local library and downloaded sometimes 12 gb on a good day mostly anime though.
This was back in 2008, but then i got my internet in October 2008

Man, I should have known I was going to open a can of worms. This is probably why they are still using deflate - when it comes to compression 100 people will have 95 opinions.

This is not an accurate test. Yes, the installers GoG uses are compressed using deflate (zip). Actually they are using a tool called "Inno Setup" to generate them, and are probably using the out of the box zip compression support (not yet sure if they're using the default zip level 7, or 9 which provides higher compression).

If you re-compress zipped content, you obviously won't see much of an improvement regardless of the algorithm you are using (because any compression decimates entropy). Re-compression is a mad man's pursuit.

A good test would be to decompress the installers using a tool like innoextract and then archiving the extracted content with LZMA2.

What I was advocating is the use of the LZMA2 compression, also supported by Inno Setup by default. It won't be much of a change for them.

Yes, LZMA is slower on decompression (and compression, though compression can be parallelized now) and if you have a high-speed hard drive or a SSD you'll suffer a bit. But after all you only need to install a game once. And taking into account the time it saved you during download due to the extra compression you might still spend less time overall than you are right now.

That's my 2 cents.

This is actually a very cool compression algorithm. It offers a very good compromise between deflate (speed) and LZMA (compression ratio), however due to the limited support at the moment, and because it's not an option to use it with Inno Setup, I doubt we'll see it used.

Linux version of Witcher 2 is a single 19.8 GB file download.

And to answer your question... I was advocating the use of LZMA both for installers in general and Galaxy-pushed updates & downloads. I don't even know if Galaxy uses compression, but a system of differential binary transfers (for updates) + compression would save a lot of bandwidth.

So the question is - does the time wasted on decompression eat the time gained from smaller downloads? Any testers?

As for Brotli, you're right, I forgot about InnoSetup. Eh.

Ok point taken. I tested it again, this time with a single-file installer because the multipart GOG installers apparently use RAR, and possibly even RAR passwords, which seem to cause extra hurdles to using innoextract. So I used Alan Wake American Nightmare because its installer exe file is in one part and it is still pretty big (1.83 GB).

So I uncompressed that with innoextract (I got about 2.35GB of files into three subfolders, app, tmp and userdocs), and then compressed the files with 7zip (LZMA2 ultra).

1970356736 bytes = the original setup_alan_wake_american_nightmare_2.1.0.24.exe
1967915313 bytes = new compressed files

So that is like... 0.12% (2441423 bytes, 2.3 megabytes?) smaller if I counted right? At least in this case the space savings don't seem significant.

Overall I'm all for GOG using the best possible compression though, just so that I save space when I keep the GOG installers on my external USB hard drive. The reason I wanted to test this was because I got an impression from your message that GOG is being wasteful with their installer compression, e.g. not compressing them much at all. Luckily to me that doesn't seem to be quite the case, even if they may not be using the very best compression method (LZMA2?). Anyway, I'm fine if GOG uses that from now on, if it is supported in innosetup.

Actually.... no. I don't have any way whatsoever of getting these downloads through a friend. My local library also has a timer on the connection, so a wifi user is automatically disconnected after 2 hours, without an option to delay the disconnect. Yes, I can reconnect almost instantly, but the only browser that will allow me to pause, reconnect, and resume without failing is Firefox. But the net speed at my library is limited to about 600 KB/s when no one else is using it besides me. And even if no one else is online, the speed is still inconsistent, fluctuating between 600 KB/s down to as low as 100 KB/s. And I just can't afford to get internet at my house, not with it costs $70/moth for only a 5MB/s download speed and a 10GB data limit. To make it worse, there is only ONE internet provider in my area, and they have a chokehold on the prices. I've checked on things like hotspot devices, but they're just too expensive. So I have to rely solely on the (limited) internet at the library.

SIGH

The woes of living in a small town out in the middle of nowhere....

are you sure that's true? I would assume the windows installer uses something better than zip, because it usually is much smaller than the linux installer. And the linux installer uses zip.

edit: relying on vague memories makes for bad statistics ... :o
just took a look again and it seems "generally smaller" isn't quite true.
some times it is significantly smaller, often pretty even and sometimes a lot bigger ...

compression ratio also highly depends on the game. If the developers already store the game assets in compressed form, then you won't get much out of compressing the files again for the installer. regardless whether you use zip, rar or lzma2.

btw: Galaxy downloads supports compression since a few versions ago, though that hasn't been rolled out to all games yet as I understand.