Hi,
You're not doing anything 'wrong' but it's not the "preferred method" to encode the audio with TMPGEnc. As DialHot said- you should use BeSweet or HeadAC3he to encode the audio because they are better audio encoders
wave file has extension-
.wav
AC3-
.ac3
BeSweet and HeadAC3he will accept either as input to encode to
.MP2 at 128 kbps.
Then after you have encoded the now smaller audio file you can use that as audio input with TMPGenc-----
or --- use BBmpeg to join the audio and video files (which is the preferred method)
ren