Yes, the 1.5.2 back end will work with the v1.2.5 or v1.3.4 versions of the GUI. The menu "Options -> Tags -> Ignore (do not read or write tags)" will prevent all header changes. The message by 2Bdecided (third-from-last message) in that "mp3gain is NOT lossless" gives a technical breakdown, but the short version is: Most of the time it's completely lossless, i.e. the hash should be the same if you make a gain change of +N and then make a gain change of -N. In some weird cases where it's not technically...
Sorry, it's more like "in 13 years I've had time to forget most of the code" :) I have no plans for any further changes, especially not changes that would require fundamental structural changes like multithreading.
Wow, a merge request after all these years. Good to know some people still find this program useful :)
[CLI] Support non-ANSI characters on Windows
Wow, that still happens sometimes? It’s been a problem since at least 2002, and it has never been fixed by Microsoft. Someone figured out a clever fix for individual programs (like MP3Gain) to avoid this problem, but I'm not sure whether this trick still works in Windows 10. Let me know if it works for you: First, in the MP3Gain folder (usually "Program Files (x86)\MP3Gain"), create an empty file. The easiest way to do this is to create an empty text file (right-click, "New >", "Text Document")....
MP3Gain directly modifies the audio data in mp3 files. All the tag stuff is optional, and wasn't even included in the earliest versions of MP3Gain.
Try the "full" version, which has all the components included. https://sourceforge.net/projects/mp3gain/files/MP3Gain-Windows%20%28Stable%29/1.2.5/mp3gain-win-full-1_2_5.exe/download
mp3gain.exe 1.5.2 is available. It's the last item on the Downloads page. https://sourceforge.net/projects/mp3gain/files/mp3gain/1.5.2/mp3gain-dos-1_5_2.zip/download The main change from 1.5.2 to 1.6.x was swapping out the mp3 decoding library on Linux builds, so I never bothered to build a Windows version. It's been over a decade since I last compiled the Windows .exe, so I don't currently have the tools installed :)