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Author Topic: Does Placing a 2 Ch source in a 7.1 Container affect sound quality?  (Read 1897 times)

jcisbig

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The title says it all: Does Placing a 2 Ch source in a 7.1 Container affect sound quality versus having JRiver output in 2 Channel only mode?

I need to set things up this way so that I can pass both a 2 Ch source (flac music) as well as 5.1/7.1 movies out of my GPU via HDMI to my receiver.  I would like to keep my 2 ch music as untouched as I can, while still being able to pass surround sound for my video files.

One thing I do notice that I'm not happy with is that JRiver seems to be filling the other 6 channels (center, surrounds, rear surrounds) with "silence", but that "silence" introduces a quiet hiss from my speaker's tweeters that is distracting during quiet moments of 2 channel music.  Are there any settings in JRiver or ideas in general on how to get rid of or reduce the hiss?

Thanks!
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mojave

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Re: Does Placing a 2 Ch source in a 7.1 Container affect sound quality?
« Reply #1 on: April 07, 2014, 02:02:49 pm »

No. But you want to choose "7.1 channels", not "2 channels (inside a 7.1 container)". The "2 channels (inside a 7.1 container)" option is there for those that want to downmix 5.1 and 7.1 content to stereo, but still use more channels for active crossovers.

JRiver doesn't fill any empty channels with anything including "silence".

If you aren't using WASAPI via HDMI then Windows could be resampling the empty channels and causing noise, but it seems unlikely.

Do you get the hiss when nothing is playing, too? What is probably happening is that your receiver is causing the hiss since it is expecting output on those channels. Do you still get the hiss when you just send stereo via HDMI?

You could set two zones - one for 2.0 and one for 7.1. Use ZoneSwitch and base it on whether the Media Type is audio or video. Setup the music zone with 2 channel output and the movie zone with 7.1 channel output.
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mwillems

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Re: Does Placing a 2 Ch source in a 7.1 Container affect sound quality?
« Reply #2 on: April 07, 2014, 02:05:11 pm »

JRiver doesn't fill any empty channels with anything including "silence".

This is true, provided that he turns JRSS mixing off under the channel settings; I think it's on by default and may be worth checking on just to make sure.  Alternatively, he can check the "mix stereo sources to 2.1 only" box if he needs JRSS mixing for something else.

None of that explains the hiss though, which is probably just the noisefloor on the receiver. Zoneswitch is probably the answer to that if he doesn't get the hiss in stereo mode.
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jcisbig

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Re: Does Placing a 2 Ch source in a 7.1 Container affect sound quality?
« Reply #3 on: April 07, 2014, 03:43:09 pm »

Thanks for the replies guys.

I'm outputting my audio through my AMD 5770 GPU via a WASAPI connection over HDMI to my receiver.  This is the only audio output that my computer has that can support passing 24/192 audio, of which I have quite a few files.

I used to have my GPU sending a stereo signal to my receiver, but I recently began using JRiver (and my computer) as a movie source since my blu ray player broke.  Because of this, I needed to re-configure my GPU to be able to send a 7.1 signal when necessary (movies).  However, I still want to maintain good 2 channel performance for my music.  The issue though is that the GPU will not allow me to output 2 channel only from JRiver, as it is requesting a 7.1 source to pass on, since it's now configured to run in 7.1. 

As things stand right now, I have three zones set up:

1) "Player" Zone
This is the "default" zone that came with JRiver.  I have this one set up as my most pure audio zone.  It outputs audio over an exclusive WASAPI connection via HDMI to the receiver.  I have the DSP output set to not do any upmixing or downmixing.  This mode produces hiss on the center and surround channels while playing a two channel source through my L/R tower speakers.  I can get the hiss to go away by: a) turning off the amp that is powering the center and surrounds, b) switching my receiver to "stereo" mode (2.1) from "direct" mode (which plays any and all channels that are coming to the receiver, in my case, a 7.1 signal from JRiver, even though the center and surround channels don't contain any audio).

2) "Music" Zone
I created this zone with all the same settings as the "Player" zone, except I did not make this one have an exclusive connection.  I wanted this mode so that I could still hear audio from Windows, web browsers, etc.  This is the zone that I use most frequently.  It has the same hiss issues as the zone above, and I can do the same things to get rid of the hiss.

3) "Movie" Zone
This zone is also WASAPI, but not exclusive.  It takes any source and, using JRSS, it creates a 7.1 output.  This works flawlessly, probably because it is "covering up" whatever hiss may or may not be there.

Any help or advice that you can offer here would be appreciated!
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