This is a tutorial to get 5.1 surround sound from your receiver (capable of handling AC3) from an AAC file. I tried hard to make this work and did lots of googling. Finally found success in doom9 forum.
Here we will be using Media Player Classic and ffdshow.
2. Open ffdshow audio decoder and choose ffdshow to decode AAC (use libfaad2 for AAC in codecs page)
3. In the Resample page, tick the checkbox for Resample. Change "resample to" box to 48000 Hz. Make sure that "Resample always" radio button is checked.
4. In the Output page (under OSD), check AC3 (S/PDIF encode mode) under Supported output sample formats. Make sure the bitrate is 640. Check "Don't use WAVEFORMATEXTENSIBLE header when not needed".
That's it. Press Apply.
Now your AAC will be passed (resampled) to your receiver as AC3 and your receiver will identify it as Dolby Digital.
Note: All the audio going thru ffdshow will be resampled. If you are using MPC for Ac3/DTS, this will reduce quality. I suggest you to use inbuilt MPC AC3/DTS decoder (which can send signals directly to s/pdif) or AC3 filter.
