Can't hear 5.1 surround in reciever from H.265 AAC with 6 Channels MKV file

Lately MKV files are distributed with the new H.265 codec (HEVC) and the audio is AAC (or HE-AAC) that has 6 channels.
I can play the files, no problem, and there is a sound, but it's 2 channels only. I had been going out of my mind trying to play all 6 channels in my system.

My system:
PC Quad core with 4GB RAM and Windows 7 64bit ultimate. Plays everything, 4K, bluray etc, no lags. I use Windows Media Center.
Marantz receiver that supports 7.1 channels. It's high quality but quite old, so no HDMI input.
I have only 5.1 speakers connected (2 front, center, 2 back and a sub)
I connect the PC to the receiver with an optical cable (and set SPDIF in the codecs)
The PC is also connected to a Samsung FULL HD TV via HDMI and to a Sony Project via the other HDMI I have on the graphic card (nVidia GeForce GT 610).
I have 2 channels sound in my TV, no issues.

I have installed the latest K lite Mega pack with no luck to make my receiver play all 5.1 channels. It only plays as stereo. I usually use LAV for video, audio and splitter since it's recommended.
If I play AC3 files I have no issues getting all 5.1 channel. I never had problems until the new codec H.265 with AAC 6 channels has arrived.
I use MediaInfo to make sure the files are 6 channels.
I tried to use AC3Filter and what I got was 2 front and 2 back playing with no center...  (so nice background music with no voice).
I don't have COAX output in my PC, only optical and the regular "headphone" connectors for each channel.
I have an external sound card (connected via USB) that has COAX (for now used on a different PC). Haven't tried it yet, if someone thinks that would solve the problem I can give it a try.

After 3 hours of trying all kinds of settings I gave up....
Can someone help me?

Ok.. Silly me... I always find the solution a sec after I give up. I googled a bit more and found the solution here:
http://www.avsforum.com/forum/26-home-theater-computers/1394553-how-play-mp4-file-aac-5-1-through-s-pdif.html#post21655053

ffdshow did the trick. I had to set something in an area I wasn't even aware of exists
So problems solved, everything works. I will leave this post online so it might help others as well.

AC3Filter also has the ability to re-encode to AC3 audio for SPDIF output. ffdshow also works fine.

I recommend enabling resample in ffdshow and set it to 48000 Hz. That should avoid problems when audio has a different sample rate that isn't compatible with the AC3 encoder.

Admin wrote:AC3Filter also has the ability to re-encode to AC3 audio for SPDIF output. ffdshow also works fine.

I recommend enabling resample in ffdshow and set it to 48000 Hz. That should avoid problems when audio has a different sample rate that isn't compatible with the AC3 encoder.

I've tried AC3Filter as mentioned and could get all 5.1 speakers to work. IDK, ffdshow worked so I'm leaving it like that.
I will set the resample as commanded, thank you.


May I ask - I couldn't get 7.1 speakers to work via SPDIF with optical cable. My receiver supports 7.1 and basically have all 7.1 speakers connected, but only 5.1 are working. A while ago I tried all kind of settings with no luck, do you have an idea? Is it hardware limitation or something with the codecs?

The AC3 encoder is limited to 5.1. Have you tried with a video that contains 7.1 DTS?

Admin wrote:The AC3 encoder is limited to 5.1. Have you tried with a video that contains 7.1 DTS?

AC3filter has settings for more than 5.1 as far as I know, but honestly I don't know what it supports.
Front AC3filter page, what does this mean:
"Up-mix any audio track (even plain stereo) up to 6 channels
Down-mix any audio track to any number of channels (to match your speaker configuration) "

I have tried LAV and it didn't work. I don't remember if I tried ffdshow, but I think so. Then again, I wasn't aware of the "output" area, I will try to test again when I have the time (my free time is very limited).
LAV recognizes DTS while AC3filter doesn't, I used to work with AC3filter but now moved to LAV, it works the best with my receiver.

I have a video test for 7.1 speakers (it plays each speaker and there's a video showing which speaker is played) and I have some movies I downloaded which have 7.1 speakers. My receiver shows which speakers are played so I know for sure that the middle speakers are not played.
I also have a bluray drive in my pc and my blurays are usually 7.1. I use power dvd to play the blurays.

Thing is - before I go crazy doing all kinds of testings, I need to know if in general have an optical cable connected from my PC to my receiver doesn't limited the number of speakers I can use. I need to know if it's most definitely a codec settings issue, or do I need to change something in my hardware. In some places I read that SPDIF can only support 5.1, I don't know if that's true. Perhaps I need to change the way I connect my PC to the receiver? IDK...

Some facts to make things more clear:

1) The AC3 and DTS formats are both limited to max 5.1. So inherently SPDIF is also limited to 5.1 as those are the only two compressed formats it supports for passthrough.
2) LAV/AC3Filter/ffdshow all support 7.1 output. But not for SPDIF. Only for uncompressed output or passthough over HDMI.
3) LAV does not have an option for re-encoding to AC3.
4) They all support DTS. So if you were having trouble with DTS and AC3Filter, it probably wasn't normal DTS audio. Bluray disc often contain DTS-HD Master Audio. That is a newer different audio format. See it as a more advanced and better quality variant of the old DTS format.
5) MediaInfo can show you details about the files you have.
6) Some sound cards claim to support 7.1 for SPDIF, but I think that information is incorrect. They probably only support 7.1 on their analog outputs. So you should try using those. You should not enable passthough and also not the AC3 encoding option in this case. The PC should decode the audio and output as normal uncompressed PCM audio.

WOW thank you very very much!!!! That is the information I was looking for.
I will use my external sound card (asus xonar u7) which definitely supports 7.1 and connect via analog and see how it goes.
Thanks again.

Hello,

So the way to fix this is to remove AAC from LAV Audio and to put it on FFDshow audio decoder libavic or other codec doesn't matter, and on output put it to convert only 5.1 AAC otherwise some stereo x265 won't play with a receiver sound. Haven't found anything in AAC beyond 5.1 so I can't say if it can do beyond 5.1 or if it's possible.

If you use SPDIF then you either have to mix to stereo or convert the audio to AC3.

If you use HDMI for the audio, then you don't need to do anything, because that supports up to 7.1 PCM.

Hi,

I was experiencing no voices sound (all the others sounds where working fine) on my VLC when watching movies, I downloaded ffdshow and it's working now.

Thanks for the tip!