This is a guide on how to properly log VGM files for Sega Game Gear, Genesis, and Master System games. To properly log VGM files, you must properly trim the file so that it properly loops.
First, you must use a Sega emulator, preferably Kega Fusion, that has VGM logging capabilities.
There are a few tools you will need to start logging VGM tunes. You will first need an emulator which can log VGMs. Fusion is a good example. There are also modified versions of MAME and MESS which log a single VGM files for each use of the emulator.
Second, you'll need a program that can play back the VGM files. in_vgm for Winamp is a good choice.
Third, you will need a program that can open the exported wave files in 'samples' so you can find the editing points. Audacity is free and easy to use.
Last but not least, you will need a program to trim the edit points and add metadata to the file. The only two VGM trimming tools available are VGMTool and vgm_trim.
All of the above mentioned programs can easily be found online.
First, load the game you wish to VGM/VGZ log. Here, we'll do something simple; Jeopardy!
Right before the song plays, hold Ctrl and press V (or click Sound -> Log VGM File.)
You will be given a choice of what the name of your VGM file will be and where to save it. When the song has played either to the end or the loop point, hold Ctrl and press V again to stop the logging. Now, open up the VGM in a player such as Winamp and make sure the song plays all the way through.
You will notice that either the song will take a moment to play because you logged to early or you'll hear a bit of the next loop at the end because of when you stopped the logging. This will later be edited with VGMTool, but first, you need an audio editor that can show samples instead of times such as Audacity. To do this, you will need to find the exact point that the music starts and when it loops. Now in Winamp, right click and go to Options -> Preferences and a window should appear. At the bottom under the Plug-ins section is a subsection called Output. Click it. Now there should be at least three different options; Nullsoft Disk Writer v2.14 [out_disk.dll], Nullsoft DirectSound Output v2.6 (d) [out_ds.dll], and Nullsoft Wave Output v2.13 (d) [out_wave.dll].
Click and highlight Nullsoft Disk Writer v2.14 and close out of the options. Now when you play the song again, a .wav file will be exported. If you don't know where the exported .wav is, you can go back to the Options -> Preferences, highlight Nullsoft Disk Writer v2.14 and click Configure to change the save path.
After the .wav is exported, it is time to open it in Audacity. This will let you know exactly when the song starts and ends so you can properly edit the meta data in VGMTool. When you open the .wav in Audacity, you must change the time to 'samples'. To do this, click the up arrow next to the first time.
After that, you must find the exact time the song begins. Make sure the 'Snap To' function is highlighted. When you find the beginning of the song, zoom in all the way and click the point that is right at the beginning of the song. When you find the first point that the song plays, write it down in Notepad. For example, the song starts at 1789 samples, so write "Start: 1789".
Now you must find the point in the song that loops. When you do, zoom in all of the way and select the time point that is right next to the loop. Here it is at 1823119 samples, so I'll write "Loop: 1823119" in Notepad. Now you are done with Audacity so close it out and don't save. You're almost done with VGM Logging!
Lastly, open VGMTool and go to the Trim/optimise tab. Enter the times you wrote down in Notepad in the appropriate fields. If you try to click Trim (old code) you will get an error saying that your times are invalid. Now copy/paste the Start samples number you got from Audacity in the Start and Loop fields, and copy/paste the end time in the appropriate field. Since the song loops, make sure to highlight Include looping. Now click Trim (old code) and a VGZ will be exported. VGM Tool will then ask to play the song in the associated program. Click Yes.
(Note: If the song doesn't loop, still place the Start time into the Loop field and don't check 'include looping'.)
Now let the song play all the way through in Winamp. Make sure you also have the loop function on in Winamp. Now your VGM should loop properly. Great job! Now all you need to do is add the meta data in VGM Tool. When you do this, make sure that Winamp is closed or else some of the meta tags will not be shown in Winamp. In VGM Tool, click on the GD3 tag tab and enter the information about the song. The songs also need Japanese titles. If you do not know Japanese, you can ask a friend who knows to help, or leave it blank if necessary. Make sure you click Update GD3 in the bottom right hand corner.
Congratulations! You have successfully learned how to make VGM files! Nice work!