5.1 via optical out

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doox00

2[H]4U
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Aug 28, 2005
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Hey all, I replaced my HT receiver in my living room so have my old onkyo receiver available to use in my new flight sim rig I built/building. I have triple 4k screens off a 2080 super atm, its just a place holder until 3090s are available to order. I am using optical out off my motherboard (msi meg ace z490) to my onkyo. I have a 5.1 setup off the receiver. The issue is windows is not allowing me to select 5.1 anywhere. But in sound settings I can do a test of dolby and dts and it plays back in all 6 speakers individually.. so I am curious if 5.1 is actually available/working? If I were to play a game that supports 5.1 would surround actually work? (have not tried, only thing installed atm is msfs 2020) I have no way of just outputting hdmi and going through the receiver to one of the screens as my receiver only does 60hz 4k pass through and these are 120hz screens with hdmi 2.1 ports. Thanks for any input.
 
doox00 said:
Hey all, I replaced my HT receiver in my living room so have my old onkyo receiver available to use in my new flight sim rig I built/building. I have triple 4k screens off a 2080 super atm, its just a place holder until 3090s are available to order. I am using optical out off my motherboard (msi meg ace z490) to my onkyo. I have a 5.1 setup off the receiver. The issue is windows is not allowing me to select 5.1 anywhere. But in sound settings I can do a test of dolby and dts and it plays back in all 6 speakers individually.. so I am curious if 5.1 is actually available/working? If I were to play a game that supports 5.1 would surround actually work? (have not tried, only thing installed atm is msfs 2020) I have no way of just outputting hdmi and going through the receiver to one of the screens as my receiver only does 60hz 4k pass through and these are 120hz screens with hdmi 2.1 ports. Thanks for any input.
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ddl/dts are 5.1 and compressed over optical. if your tests work, games should too. mine do.
 
doox00 said:
So do games and such use PCM for surround?
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No, PCM over Optical / TOSLINK is only 2 channels. PCM is what CDs use, and the standard has largely remained the same over the years. When you were testing, your computer was likely sending a Dolby Digital or DTS signal to your receiver, which is different from PCM. PCM is not compressed. Dolby Digital and DTS are compressed, sort of like MP3, which is why you can fit more channels.

To play a game using Dolby Digital or DTS output (instead of 2 channel PCM) you need to encode/compress the signal into Dolby Digital or DTS on-the-fly. Many audio solutions do support this, but you have to specifically enable it. The problem with this has always been latency. It takes time to encode/compress the audio into Dolby Digital or DTS and that delay can be noticeable, making it less than optimal for gaming. You don't have that same delay when using Dolby Digital or DTS to watch a movie, because the movie audio has already been pre-encoded. Encoding/compressing your audio into Dolby Digital or DTS also results in a slight loss of quality, sort of like encoding a CD into MP3 files.

See if your receiver has multi-channel analog inputs. Connect the analog outputs on your soundcard or motherboard audio to the multi-channel analog inputs on the receiver. You'll be using the DAC in your soundcard or motherboard audio at that point, instead of the DAC in your receiver, but it's a simple and effective solution.
 
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GotNoRice said:
No, PCM over Optical / TOSLINK is only 2 channels. When you were testing, your computer was likely sending a Dolby Digital or DTS signal to your receiver, which is different from PCM. PCM is not compressed. Dolby Digital and DTS are compressed, sort of like MP3, which is why you can fit more channels.

To play a game using Dolby Digital or DTS output (instead of 2 channel PCM) you need to encode/compress the signal into Dolby Digital or DTS on-the-fly. Many audio solutions do support this, but you have to specifically enable it. The problem with this has always been latency. It takes time to encode/compress the audio into Dolby Digital or DTS and that delay can be noticeable, making it less than optimal for gaming. You don't have that same delay when using Dolby Digital or DTS to watch a movie, because the movie audio has already been pre-encoded.

See if your receiver has multi-channel analog inputs. Connect the analog outputs on your soundcard or motherboard audio to the multi-channel analog inputs on the receiver. You'll be using the DAC in your soundcard or motherboard audio at that point, instead of the DAC in your receiver, but it's a simple and effective solution.
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Nice, okay thanks for the info. I was thinking about that, running individual cables for each channel.. I think my receiver does have analog inputs for each, I will verify that. Also, anyone know if a dp to hdmi cable would work to the receiver for sound? I imagine it will add a ghost monitor doing that but probably won't be an issue for me if it does. I will be running the 3 4k screens in surround I think once I get a 3090 and can just toss the ghost screen up in a corner or something. May be easier to do a dp to hdmi cable than run individual analog cables to the receiver if that works.
 
doox00 said:
Nice, okay thanks for the info. I was thinking about that, running individual cables for each channel.. I think my receiver does have analog inputs for each, I will verify that. Also, anyone know if a dp to hdmi cable would work to the receiver for sound? I imagine it will add a ghost monitor doing that but probably won't be an issue for me if it does. I will be running the 3 4k screens in surround I think once I get a 3090 and can just toss the ghost screen up in a corner or something. May be easier to do a dp to hdmi cable than run individual analog cables to the receiver if that works.
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It does, but it does add a ghost monitor, and that can... screw with a lot of things.
 
GotNoRice said:
No, PCM over Optical / TOSLINK is only 2 channels. PCM is what CDs use, and the standard has largely remained the same over the years. When you were testing, your computer was likely sending a Dolby Digital or DTS signal to your receiver, which is different from PCM. PCM is not compressed. Dolby Digital and DTS are compressed, sort of like MP3, which is why you can fit more channels.

To play a game using Dolby Digital or DTS output (instead of 2 channel PCM) you need to encode/compress the signal into Dolby Digital or DTS on-the-fly. Many audio solutions do support this, but you have to specifically enable it. The problem with this has always been latency. It takes time to encode/compress the audio into Dolby Digital or DTS and that delay can be noticeable, making it less than optimal for gaming. You don't have that same delay when using Dolby Digital or DTS to watch a movie, because the movie audio has already been pre-encoded. Encoding/compressing your audio into Dolby Digital or DTS also results in a slight loss of quality, sort of like encoding a CD into MP3 files.

See if your receiver has multi-channel analog inputs. Connect the analog outputs on your soundcard or motherboard audio to the multi-channel analog inputs on the receiver. You'll be using the DAC in your soundcard or motherboard audio at that point, instead of the DAC in your receiver, but it's a simple and effective solution.
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The problem I have always had with analog 5.1 is that movies and other Dolby/DTS content never seemed to decode and play properly over multichannel. I ended up going with Optical for simplicity, and it seems to work fine. I haven't been able to discern a huge difference between the two in gaming.
 
Turns out my receiver does not have individual analog inputs. I will see how it goes with optical and if it is not working as well as I would like I will run a dp to hdmi to my receiver and use sound that way and hope the ghost monitor does not screw with things to much.
 
MavericK said:
The problem I have always had with analog 5.1 is that movies and other Dolby/DTS content never seemed to decode and play properly over multichannel. I ended up going with Optical for simplicity, and it seems to work fine. I haven't been able to discern a huge difference between the two in gaming.
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The problem is that an optical connection does nothing for you if you are watching a movie that uses a newer codec such as Dolby TrueHD. Either your movie will fall-back to a lower resolution backup codec (traditional Dolby Digital or DTS), or it will downmix the output into stereo, leaving your receiver to try and re-expand that into multichannel using something like Dolby Pro-Logic or DTS Neo:6.

When you are feeding multi-channel analog output from your computer into the multi-channel analog inputs on your receiver, your computer is doing 100% of the work when it comes to decoding anything. So if something doesn't work right, it's almost certainly a configuration issue with your computer. The most common would be to make sure that your computer is set to 7.1 output, otherwise your computer will usually attempt to downmix whatever you play into the number of available channels that you have set.

I have my main HTPC feeding into an older 7.1 receiver that, while still very capable, does not support the newer audio codecs. Using the 7.1 analog outputs on my soundcard into the 7.1 analog inputs on my receiver allows me to play newer movies that use Dolby Digital TrueHD or DTS-HD Master Audio instead of being limited to traditional Dolby Digital, DTS, or Stereo, and it works great. No decoding issues. It's easy enough to check the channel assignment using test files:

http://gotnorice.com/DOLBY_TRUEHD_SOUND_CHECK_71.mkv
http://gotnorice.com/DTS-HD_MA_SOUND_CHECK_71.mkv

If sound is coming out of the correct speakers, then you are good to go. If it's not, then you have a configuration issue, almost certainly on the computer end.
 
I won't be watching any movies on this pc, only playing games on it (flight/race sim type games mostly). If the game supports surround I want to be able to take advantage of that.. I have to do some testing and see how it works with optical like I have now, if it is not working I will just deal with a ghost screen I guess.
 
Every Realtek chipset is capable of compressing 5.1 audio from games into either Dolby Digital or DTS, but in most of them the feature is soft-locked away due to licensing stuff. However you can download unlocked 3rd party drivers and they work just fine, just select either DTS or Dolby output mode in your soundcard settings. I have not heard any major lag issues either. Google Realtek Dolby unlocked driver and you should find forums discussing this and download links.
 
MaZa said:
Every Realtek chipset is capable of compressing 5.1 audio from games into either Dolby Digital or DTS, but in most of them the feature is soft-locked away due to licensing stuff. However you can download unlocked 3rd party drivers and they work just fine, just select either DTS or Dolby output mode in your soundcard settings. I have not heard any major lag issues either. Google Realtek Dolby unlocked driver and you should find forums discussing this and download links.
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laptopvideo2go.com is my go to for those. scroll down, scroll waaaay down to the sound/realtek section and go to the last page of the driver thread.
 
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