Surrond AAC (1 Viewer)

[Scott]

Got some 5.1 AAC audio tracks and can only get stereo output. Using the latest FFDShow and AC3Filter and trying to output over SPDIF. Anyone got any tricks to getting this to work?

MediaPlayer Classic and Windows media Player can both do it using AC3Filter but mediaportal wont let me use AC3Filter for AAC

thanks

 

[kiwijunglist]

lots of stereo receivers only support 2 channel AAC pass through over SPDIF.
ie my stereo can decode 2 channel AAC.
if i feed my stereo 5.1 AAC it only decodes Front L/R channels
you can setup ac3filter to re-encode AAC to a different format eg AC3 and then pass through
not sure if you can specifically setup to only re-encode 5.1 and leave 2 channel alone.

 

[paony]

realtime aac -> ac3 transcoding

I have the same problem as scott. I have set up the following direct show filterchain (only audio branch shown)
for mkv files with aac 5.1 sound:

media splitter -> ffdshow audio decoder -> ac3filter -> audio renderer (see attachment)

I have checked this with graphstudio.
It also runs runs like this in windows mediaplayer.

but in mediaportal it allways ignores the ac3filter and uses the following scheme:

media splitter -> ffdshow audio decoder -> audio renderer

this happens even if i check
video -> video player -> automatic decoder settings
in mediaportal configuration.
It seems that mediaportal does not setup the direct shown chain according to the merits, even if the above configuration option is set.

I suppose it would work if ac3filter would support aac input natively (as it does for mp3 and aac):

media splitter -> ac3filter -> audio renderer

but unfortunately it is not supported and so ffdshow audio and ac3filter have to be chained.

It would be nice if mediaportal could support this in the future, in the meantime i have to use ms mediaplayer to get 5.1 sound with aac

best regards
Stefan

 

[Owlsroost]

You could try adding AC3 filter as a 'postprocessing' filter in MP config - I do this to force FFDShow (audio decoder) into the graph for upmixing/downmixing when another decoder is being used.

Does the built-in AC3 encoding in FFDShow not work ? (instead of using AC3 filter for this purpose)

Tony

 

[paony]

I tried both - and both works - really cool.

Stupid that I didn't find that out myself.

Thanks for your quick support - now I don't have to use ms mediaplayer anymore

cheers

stefan

 

[kiwijunglist]

Solution: Install FFDShow audio codec and use that codec for AAC, FFDShow will decode 5.1 AAC -> 5.1 AC3. When you install FFDShow unfortunately it also installs video codec, so you must unselect all options except for AAC. You should also block MP from access FFDShow Video codecs, by removing mediaportal from the list of allowable programs during the video codec install.

Now I have MPA Audio decoder (SPDIF) decoding/pass through all sounds except for AAC which is handled by FFDShow.

NB - I originally tried using the following graph
Video -> Splitter -> Monogram AAC -> AC3Filter (Post processing)
But this messed up the channel order because the channel order in AAC is different to AC3, ie Center AAC channel will come out the front right channel if you use AC3 for post processing.