Changing pitch in 5.1 AC3 and saving back to 5.1 AC3?

[Morac]

I currently have a divx/ac3(5.1) avi where the audio is pitched too low so I want to change it. I tried doing so with VirtualDub 1.8.4 and AC3ACM 1.4 and everything looks like it's working until I actually go to save the avi when I get this error message:

"Error initializing audio stream compression
The audio codec cannot compress the source audio to the desired format
Check that the sampling rate and number of channels in the source is compatible with the selected compressed audio format"

Doing some searching I found a thread (http://forums.virtualdub.org/index.php?act=ST&f=3&t=15253) at the Virtualdub forums that states that for whatever reason VirtualDub with AC3ACM cannot convert from ac3 5.1 to ac3 5.1.

Things I've already tried:
1. Converting to 2 channel mp3 works, but I want to keep it at 5.1 channels.
2. Converted extracted ac3 to 6 channel wave file, but it doesn't play back since it says I'm missing a codec.

I want to keep everything the same, just up the pitch. Is there any other way to do so?

[tebasuna51]

You can use BeHappy and Aften encoder.

[pc_speak]

\AviSynth 2.5\Docs\english\corefilters\timestretch.htm
TimeStretch(pitch = 200)
This will raise the pitch one octave, while preserving the length of the original sample.

[MicoMaco]

Check your private message, it may help.