AAC 5.1 playback on home theater receiver problem

[Phat J]

Hey everyone!

So I've recently got a new home theater receiver and 5.1 speakers, and I'm outputting HDMI video and optical audio from my PC to the receiver and the TV.

To my understanding, the software filters like AC3Filter and FFDShow allow formats like AC3 and DTS to pass through for the external receiver to decode, and I have it set that way, and it works great.

The problem is with 5.1 AAC audio; my home theater receiver does not support decoding of this format, so pass through won't work.

After a bit of online research, I found that the AAC format needs to be pre-processed to AC3 by the computer, then it will be decoded by the receiver as Dolby Digital. I set this in AC3Filter as shown:



When I playback a movie with AAC audio, it shows AC3Filter is in use re-encoding the AAC to AC3:



My receiver says "Dolby Digital" while this is being played back. However, as you can see in the input / output graphs above, it shows the 6 channels going, but only outputting 2 channels. Also sound on my receiver only comes out of Stereo left and right. It makes no difference if I choose 5.1 or "AS-IS" from that drop down menu on the Output part of the above pic, it still only outputs it as stereo.

Anyone have any insight on this? Why wouldn't AC3 filter keep and output all 6 channels?

Thanks!

[Phat J]

Well after some more trial and error, it appears I have solved it!

Instead of using AC3Filter at all, I enabled the AC3 encode feature in FFDShow and disabled it to decode any other formats except AAC.
Now it plays the 5.1 properly! Turns out AC3Filter just sucks at doing this.

Thanks anyway ...

[jamesm113]

Well after some more trial and error, it appears I have solved it!

Instead of using AC3Filter at all, I enabled the AC3 encode feature in FFDShow and disabled it to decode any other formats except AAC.
Now it plays the 5.1 properly! Turns out AC3Filter just sucks at doing this.

Thanks anyway ...

Hello,
How did you set up the AC3 encode feature in FFDShow? I'd like to do the same. Thanks!

[slvbeard]

I'd be curious how you did this in FFDShow as well...

[Phat J]

Sorry for the late reply. To enable the AC3 encoding in FFDshow, open the audio decoder configuration, and on the far left, scroll down to Output. Then check the AC3 and Encode 5.1 boxes. I put it at max quality:

*Note: you probably have to check off the pass-through options like I have as well. Since it will encode the AAC to AC3, I would assume you'd have to have the AC3 pass through on too.

[aaryan.varun]

how much time does it take to convert AAC 5.1 to AC3 5.1 i.e dolby digital 5.1???