Ok you have a MPEG video and you want to add sound to it in the form of a WAV file. This is how to do it for for free.
You will need to download Aften.exe and an Aften GUI. You can get them here. http://www.videohelp.com/tools/Aften
Once you have downloaded and extracted them you just need to put the aften.exe file into the same folder as the aften gui program. To start the Aften with the graphical interface click on the GUI file. Alternatively, if you are happy with the command line, you can just use aften.exe on it’s own.
Aften converts a WAV file into the AC3 format. You don’t need to change any settings just add your WAV file and click encode.
Next you need to download and install avidemux http://fixounet.free.fr/avidemux/
Screen recording of the following steps can be seen here. http://www.youtube.com/watch?v=TohMfcNZlxY
1. Open your MPEG video in Avidemux (you can just click and drag it over).
2. Click AUDIO in the top toolbar/ MAIN TRACK/ Change the dropdown menu AUDIO SOURCE from VIDEO to EXTERNAL AC3. Then browse for your file. OK
3. Change AUDIO drop down on left toolbar from COPY to AC3 Aften. Click FILTERS button/ tick RESAMPLING check box (setting needs to be the default 48000). OK
4. Change FORMAT left toolbar from AVI to MPEG-TS (A+V).
5. Click FILE on top toolbar. SAVE/ SAVE VIDEO/ name your new file and select destination. SAVE
6. Right click your new file and RENAME and give it the file extension .MPEG eg yourfilename.MPEG
Done. If you need any further help please leave a comment.