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How to connect a PC to an AV Receiver for the best quality audio?
December 15, 2011 10:28 AM   Subscribe

How to connect a PC to an AV Receiver for the best quality audio?

I recently purchased an Onkyo TX-NR709 AV Receiver. I'm using it to intermediate between my TV, speakers, and PC. I am using the PC as the source for all media (MP3s, Netflix, Blu-Ray, etc.) The Windows 7 PC is feeding the signal out an HDMI cable via an ATI Radeon HD 5770.

The issue I'm having is dealing with the bewildering array of settings on the PC. It seems like there are multiple system/driver settings panels and application specific settings that all affect the end result that gets pushed out the HDMI. What I really want is to have as accurate a signal as possible, with a minimum of processing and manipulation done to the bits on the PC that get sent to the receiver.

Some specific questions that have come up:

1) There is a system volume control, as well as application specific volume controls for the digital audio (which gets sent out the HDMI). My understanding was that the volume should be 'fixed' at whatever the source is and just have the bits sent out the HDMI. Apparently this is not the case. What level should I set in order to ensure the signal has had a minimum of manipulation done to it? (I want to keep the level at reference and avoid applying any gain to it, which could introduce distortion and clipping). The manuals and reference materials I've been able to find have been remarkably unhelpful on this.
2) Are there any guides that outline, in painful detail, how to avoid all processing and hidden manipulation settings on the PC side of things? I'm still finding obscure settings that, say, would do the audio decode on the PC end instead of sending to the receiver like I want. I've searched through ask mefi and avsforums but haven't been coming up with much.
3) Would something like XBMC allow greater control over the parameters I'm concerned about, or is that merely a nice interface for controlling media access?

I'm in the IT field and am comfortable getting as technical as required to accomplish my goal.

Any advice is greatly appreciated, thanks!
posted by 1024x768 to Technology (9 answers total) 5 users marked this as a favorite
Volume should be fixed. I have a ATI 4570 and the volume controls do nothing, only mute works.
IIRC, I have no settings on my ATI HDMI audio under sound settings as it should just bitstream to the receiver.

You may want to try updating your driver, or use the Realtek ATI HDMI audio driver (which is what I use).
posted by wongcorgi at 11:27 AM on December 15, 2011

My understanding was that the volume should be 'fixed' at whatever the source is and just have the bits sent out the HDMI. Apparently this is not the case.

Are you sure you're bitstreaming and not instead having the PC decode to PCM and sending that over HDMI to the receiver? As you and wongcorgi have noted, volume should be unaffected when you are bitstreaming.

What is your preferred media playback software?
posted by Inspector.Gadget at 11:31 AM on December 15, 2011

wongcorgi, I will try updating my driver/trying that driver, thanks.

What is your preferred media playback software?

I used VLC for most local media files. For Netflix/Grooveshark/misc web streams I have to use their in browser flash (I use Chrome or Firefox for web browsing, if it matters). For Blu-Rays I use the Cyberlink PowerDVD software that came with my Blu-Ray drive.

The receiver does indicate it's receiving a PCM stream from the PC for most things. The only time I had something else was when playing a Blu-Ray disk that output one of the flavors of Dolby Digital (and the system volume affected that as well).
posted by 1024x768 at 11:51 AM on December 15, 2011

I think a couple terms here need to be separated. Bitstreaming vs. PCM does not necessarily indicate whether the signal is being distorted / pre-amped. You want to make sure you are outputting a line-level signal even when you're not bitstreaming. At line-level output the card sends a signal that is as clear as possible. You can have line-level stereo PCM audio even if it's being decoded in the PC. Any multi-channel audio formats, however, you want to passthrough / bitstream directly to your receiver.

Your goal is to output a line-level signal for stereo PCM output for any stereo media (such as flash), and enable bitstream/passthrough for AC3/DTS/whatever in VLC / Cyberlink / DVR player.

To get there, you need to do two things.

1. You should be able to get a line-level signal from your HDMI output. The fact that your system volume affects the output volume indicates you're not. The card is configured wrong and you probably need to fix that in Windows audio settings, or by updating/replacing the drivers as wongcorgi suggested, or you may need to adjust settings in the Catalyst control panel.

2. For audio passthrough, VLC and Cyberlink need to be configured correctly. Look for references to S/PDIF audio passthrough. This is a checkmark in the audio preferences screen in VLC. I'm not sure how to do this in Cyberlink but it will be the same type of setting.
posted by dosterm at 1:24 PM on December 15, 2011

Also, XBMC is a nice GUI for managing your media but will give you fewer audio output options than VLC. It won't resolve this issue on its own. That said, if you want to try it out, it does support passthrough to a receiver and should work fine when you get the other issues sorted out.
posted by dosterm at 1:32 PM on December 15, 2011

I would switch to Media Player Classic Home Cinema as a general-purpose player and use LAVFilters (a Directshow filter bundle) to handle all decoding functions. LAV Audio can bitstream all multichannel DVD and Blu-ray audio over HDMI given appropriate hardware, and when you need to decode on the PC, it can use a dll from Arcsoft TotalMedia Theatre to perform reference decoding of all DTS audio types (AC3/EAC3 decoding is built on ffmpeg and should be aurally transparent, and MLP/TrueHD decoding is built on ffmpeg and of course lossless).

Incidentally, LAV Video can perform good hardware deinterlacing (CUVID,DXVA) or software deinterlacing (YADIF) and can accelerate hardware video decoding using CUVID. With MPC-HC, look into using either the EVR-Custom Presenter renderer (easy to use, generally not-buggy, configurable) or madVR (best for power users, configurable 3dlut, configurable scalers (Lanczos/Blackman/Biciubic/etc.) and strengths for resizing, Direct3D exclusive presentation mode, good screen resolution control options).

PowerDVD is bloatware but may be the best option for disc content because of its "Theater" interface mode. Having said that, PowerDVD is just garbage for anything else because it basically uses a crippled DirectShow environment and assigns high priority to its own limited, often-buggy filters.
posted by Inspector.Gadget at 1:56 PM on December 15, 2011

wongcorgi, I tried installing that realtek driver. I still see the volume control! I do note that the highest level is labeled 0db, so I'm assuming that at least won't be affected the signal level, even I can't seem to get it to simply output line level with a checkbox. I've checked every windows system panel that looks even vaguely related, and the catalyst control panel and there does not appear to be a way to force a volume-control-less mode.

Inspector.Gadget, I agree PowerDVD is pretty terrible as software goes. I've installed the MPCHC and LAVfilter you recommended and am going to experiment with them.

Thanks for your advice, everyone!
posted by 1024x768 at 7:42 PM on December 15, 2011

There isn't really a way to force direct passthrough of stereo PCM in Windows, as far as I can tell. Just put the system/wave volume at max and keep it there.

Personally I've had much better success using MPCHC with ffdshow-audio for DTS/AC3 pass-through. VLC tends to glitch the bitstream (happened to me with two different sound cards).
posted by neckro23 at 6:42 AM on December 16, 2011

"Minimum of manipulation" means everything on the PC side is going to be at 0dB, which, speaking as someone who has connected his PC to a stereo for over 10 years, isn't going to happen. Every piece of software, not to mention every source file you have, has a different volume, that's just the way it is. Some will be too loud, some will be too soft, no matter what combinations you're working with.

ReplayGain is something you may have heard of on the MP3 side that deals with this problem, but sadly I have not found a be-all end-all solution to wiggling with the volume all the time. Well, not *all* the time, but you'll definitely have a period of adjustment while you settle into a system.
posted by rhizome at 10:11 AM on December 16, 2011

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