Stage Music Editing Breakthrough
I’ve worked out a way to create Stage Music files (for the normal stages) that will play a single song all the way through from start to finish without cutting out at all. This will allow people to create Stage music using any of their favourite songs - since the music doesn’t cut out or change tempo it means you can use songs with lyrics and it won’t sound odd… i’ve already been playing matches to some Coheed and Cambria. 
You’ll need the original song in MP3 format (which most people probably have) and you’re good to go.
You’ll also need some of the encoding and packing tools mentioned earlier in this thread, but it’s actually really easy to do so don’t worry if you’re not very good at editing music (i’m certainly not). Everything you need is in this Zip file,
http://www.megaupload.com/?d=8N9JJT1W
(Even if you’ve got hardly any experience editing I would recommend giving this a try as it is very easy, just follow the instructions)
First of all you need to open your MP3 with Audacity, then simply choose to ‘Export as Wav’ from the menu - this will create a .Wav file of your song.
Next you need to use adxencd.exe to convert your .wav song into .adx format - again this is very easy. Just drag the wav file onto the adxencd.exe file (in Windows) and it should automatically create the same song in .adx format. Make a note of the file name and location.
Now you need to use CSB_Packer.exe to create your final Stage music file. It’s best if all your files are in the same folder for this next bit, as it will be easier to find them.
Run CSB_Packer and you will see 7 slots that you need to fill with files - I’ve included 2 of the files you need for this so all you need is your choice of song in .adx format (which you have already created). In the first slot (called Sound Bank) browse and select the BGM_Stage.csb file (included).
Now we have 6 audio slots to fill.
In slot 1 choose the file ‘nothing.adx’ (included)
In slot 2 choose your song in .adx format (the file you created)
In slot 3 you should again choose the file ‘nothing.adx’ (included)
In slot 4 you should again choose your song in .adx format (the file you created)
In slot 5 yet again choose the file ‘nothing.adx’ (included)
In slot 6 yet again choose your song in .adx format (the file you created)
Now click on ‘Create CSB’ and it will create a file called ‘BGM_Stage.csb.new’ - this is your stage music. 
(If you can’t see the .new part of the filename you might need to change a windows folder option to allow you to see file extensions).
All you need to do now is rename this file so that it matches the stage you want your music to play on and then copy it to the correct SF4 folder.
The stage music is located in this folder C:\Streetfighter4\Battle\System\
In order to explain which file relates to which stage I will list them in the same order they appear on the stage select screen in VS mode - if you imagine the 3 rows of stages on this screen you’ll understand what I mean, so looking at the VS stage select screen from left to right these are the stage music files,
RANDOM BGM_USA.csb, BGM_CHN.csb, BGM_RUS.csb, BGM_BRA.csb, BGM_AFR.csb
BGM_VIE.csb, BGM_JPN.csb, BGM_EUR.csb, BGM_SCO.csb, BGM_JPX.csb, BGM_LAB.csb
BGM_RVR.csb, BGM_VCN.csb, BGM_CNX.csb, BGM_VNX.csb, BGM_BRX.csb, BGM_TRN.csb
So if you want your song to play on the USA stage (the one with the cars in the background) you would simply rename BGM_Stage.csb.new to BGM_USA.csb (making sure to delete the .new file extension so that the file ends with .csb) and then copy it to the correct SF4 folder - C:\SF4\Battle\System\ (Remember to back up your original sound files from this folder in case you want to change back to the original music).
Now you should be able to fight along to your favourite songs!
Wow this turned into a long post.
Most of the credit for this should go to ‘goshanes’ as he created the CSB_Packer program, and without that we wouldn’t be able to do anything. So a huge thank you to him for creating it!
P.s.
I think this discovery deserves it’s own thread as it allows fully custom music on all the stages (I think a lot of people would like to know about this), but I don’t have the ability to post new threads yet. If anyone wants to copy what i’ve written and post it in a new thread on my behalf they are more than welcome to. Thanks.
As a final and more technical side note - the reason this works is because sound clips 2,4 and 6 are all loops and they all start playing at the same time (at the start of the fight). My ‘nothing.adx’ file is simply 1 second of silence - i used this so that the intro sound clips 1,3 and 5 don’t do anything. When the song changes (due to 2 ultras being ready or low health) the game simply switches to sound clip 4 or 6, but because I put the exact same song for those clips it just continues playing as if nothing happened. Obviously this wouldn’t work if the loop sound clips started playing at different times (the song would probably restart), but it seems we got lucky for once. lol
The only downside are the rather large sound files that you end up with doing it this way, but that can’t be helped.
I’d recommend that people read the above post if they want to create their own music - I know it probably looks scary but it’s really easy to do.
