Do you mean that you are trying to convert the .GBS to .MP3, .OGG, or.FLAC? The reason I ask, is that the .GBS file IS the music…
If you just want to play it, You can get:
WinAmp (http://forums.winamp.com/showpost.php?p=2984799&postcount=2) and ChipAmp (http://www.chipamp.org/)
FooBar2000 (https://www.foobar2000.org/download)and the respective Component(s) (https://www.foobar2000.org/components/tag/game+music) (In most cases, Game Emu Player will cover you pretty well)
or any of several other players (http://www.zophar.net/utilities/audio-players.html).
If You want to convert it, I highly recommend the Foobar or WinAmp options.
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Edit: Looping is, more or less, dependent on the length you set. Some of the plugins have a "Loop count" setting, while others have a "Default Length" setting. I usually set my "Default Length" at roughly 3:00 to 3:30 (Anything longer gets pretty redundant, In most cases)
As far as tag editing goes, It’s kinda hit-and-miss. Again, I’m not sure about WinAmp, but You can edit tags [for most formats] and Title appearances with FooBar2000.
The reason you get the 1/x is because of the contained subsongs. A .GBS [or .NSF, or .KSS, for that matter], if properly ripped, will usually contain the entire soundtrack for a game. So "x" is the total number of subsongs within your file. If you’re using Winamp, I don’t think there’s a way to get rid of that, but FooBar is quite customizable in that aspect….
…and I swear I’m not playing favorites with FooBar2000!!! Lol! I wish I could use WinAmp as much as I did in High School, but it doesn’t seem to play well on Win8/10 like it did for XP and below… XD
And that’s really about the best I can help you…
Just out of curiosity, where are you getting your .gbs file? Zophar’s Domain, by chance?