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ecsjr32
02-10-2014, 11:38 AM
Greetings,
Has anyone had succes using optical from a laptop to pass-through Dolby 5.1 surround sound audio? My receiver is only getting a PCM track in which it decodes and produces a 3.1 channel audio output to me. I see no settings in the menu to enable 5.1 surround... When I open a video file or movie or anything else that had Dolby track it works fine. Just not AC4BF? Please help.

Anykeyer
02-10-2014, 12:31 PM
Pass through? Games don't produce encoded audio. Its not a static movie we are talking about, game audio has to be rendered in real time. WWise (its a sound system used in all recent AC games) checks your system settings and automatically adjusts it's ouput, so if you want 5.1 then simply set 5.1 in your windows sound settings. Then if you want to output 5.1 using SPDIF you need a sound card with DD Live or DTS Connect support (DD/DTS realtime encoders) and enable it ofcourse. SPDIF does not support more than stereo in PCM, and no game would include its own DD/DTS encoder since it costs money and most users (those who use line outs or HDMI) dont need it.

ecsjr32
02-10-2014, 12:39 PM
Just to be clear... I have the Windows 7 OS sound settings, set to the SPDIF audio only. Enabled DTS and Dobly in those same Windows 7 settings. I have a Cirrus Logic CS4206B sound device... No matter what I do, I cannot get 5.1 audio because of the sound card or because games don't output 5.1 audio through optical no matter what (optical) sound card, 5.1 is only available through HDMI or...?

What do you mean by SPDIF does not support more than stereo?

Anykeyer
02-10-2014, 12:55 PM
Just to be clear... I have the Windows 7 OS sound settings, set to the SPDIF audio only. Enabled DTS and Dobly in those same Windows 7 settings. I have a Cirrus Logic CS4206B sound device... No matter what I do, I cannot get 5.1 audio because of the sound card or because games don't output 5.1 audio through optical no matter what (optical) sound card, 5.1 is only available through HDMI or...?

What do you mean by SPDIF does not support more than stereo?

PCM is uncompressed/original audio waveform. SPDIF provides enough bandwight for only 2 channels in PCM. Thats why you have to use encoded/compressed audio formats like DD/DTS if you want 5.1 through SPDIF.

Game would output 5.1 as soon as it will see 5.1 set for your current (default) audio device in the windows control panel. With most sound cards you actually need to make your line outs (not SPDIF) the default device, set 5.1 for line outs and then enable DD Live for SPDIF. Refer to your sound card's manual.

Simply enabling DD/DTS (not DD Live or DTS Connect) in SPDIF wont do the trick for you. This setting controls build-in Windows decoder. When you disable any of this Windows will decode DD/DTS and output it as stereo PCM. But games arent movies, you dont have DD/DTS in them. You have to encode game's own 5.1 PCM into 5.1 DD/DTS using DD Live or DTS Connect. Not all sound cards support this.

ecsjr32
02-10-2014, 01:17 PM
Simply enabling DD/DTS (not DD Live or DTS Connect) in SPDIF wont do the trick for you. This setting controls build-in Windows decoder. When you disable any of this Windows will decode DD/DTS and output it as stereo PCM. But games arent movies, you dont have DD/DTS in them. You have to encode game's own 5.1 PCM into 5.1 DD/DTS using DD Live or DTS Connect. Not all sound cards support this.

Ok so AC4 Black Flags audio file is only 5.1 PCM. The only way for the pc to get 5.1 audio is to encode to DD5.1 or DTS5.1 on the fly. This requires special sound card... I'm trying to make sure I understand. Do I have that much right? If I use the HDMI out to receiver, does the graphics card convert that to DD5.1 or DTS5.1 or does it leave it as PCM5.1?

Also, I don't have any "line outs" on my PC? Are you referring to Red and White audio ports? Or something else? My only Audio out port is a 3.5mm audio jack that supports toslink optical.

Lastly, my sound card doesn't have any special program or settings to configure in addition to the Windows settings. My only settings are right-clicking the audio icon in the taskbar then selecting playback devices... Are there other settings to configure elsewhere?

Anykeyer
02-10-2014, 01:34 PM
Ok so AC4 Black Flags audio file is only 5.1 PCM. The only way for the pc to get 5.1 audio is to encode to DD5.1 or DTS5.1 on the fly.
Yes, exactly. Any game, not just AC4.

This requires special sound card...
Sometimes built-in codecs do have DD Live support, but often you would need a special sound card.

If I use the HDMI out to receiver, does the graphics card convert that to DD5.1 or DTS5.1 or does it leave it as PCM5.1?
Video cards dont have encoders (DD Live or DTS Connect) but HDMI has more than enough bandwight for 5.1 PCM. You should not have any issues if you just use HDMI instead of SPDIF. Just remember to set 5.1 in your HDMI settings.


Also, I don't have any "line outs" on my PC? Are you referring to Red and White audio ports? Or something else? My only Audio out port is a 3.5mm audio jack that supports toslink optical.
Line out is your typical analog output as opposed to digital intefaces like SPDIF or HDMI. It can be an audio jack or RCA. Usually notebooks dont have 5.1 line out physically but still allow you to set 5.1 in drivers for compatibility reasons (because many apps check this setting).


Lastly, my sound card doesn't have any special program or settings to configure in addition to the Windows settings. My only settings are right-clicking the audio icon in the taskbar then selecting playback devices... Are there other settings to configure elsewhere?
Usually manufacturer's website provides some additional software. Check cirrus logic and your notebook's websites

ecsjr32
02-10-2014, 03:02 PM
I appreciate the help. One more question... When I set my Windows SPDIF audio setting to Dolby and "play test sound" it sends DD5.1 to my receiver. What is that doing for me overall, game, file, and system related?

Anykeyer
02-10-2014, 04:29 PM
I appreciate the help. One more question... When I set my Windows SPDIF audio setting to Dolby and "play test sound" it sends DD5.1 to my receiver. What is that doing for me overall, game, file, and system related?

Windows plays its own small prerecorded DD sample for this test. This is your receiver test (to make sure it understands the format) more than anything else. Games dont have any prerecorded soundtrack since they are interactive media. Integrating DD encoder in games would raise prices, because Dolby and DTS want money for each device/copy. On consoles this is solved by having DD Live encoder integrated in their operating systems, on PC you need a sound card that supports it. Or just go with HDMI since uncompressed 5.1 PCM is always better than DD 5.1 (DD is lossy format like mp3)