Win Volume Control Disabled in Passthrough Mode
#1
Recently, I have found that the HDMI audio to my digital soundbar performs best if Passthrough is enabled.

Image

However, if I am watching Recorded TV or Live TV and I attempt to adjust the volume, I get a message like**, "This feature is disabled when Passthrough is selected."

** Sorry, but I'm not in front of my media PC at the moment, so I cannot give the exact text or supply a screenshot!

Is the WMC Server or backend client causing this?

The audio controls work fine when playing our other videos on our network drive.

How can I fix this?
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#2
That's interesting. We don't control anything related to volume in the add on, this must be an xbmc-live TV thing, I will move the thread to general pvr support .
Windows Media Center PVR addon (pvr.wmc) and server backend (ServerWMC)
http://bit.ly/serverwmc
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#3
Passthrough by definition is untouched and simply "passed through" the device. As such there is no volume control from your PC and it's up to your AVR or whatever is being fed and decoding the untouched audio to control the volume. Does your sound bar have a volume control?
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#4
Yes. The soundbar is on Max. This way, the MC Remote controls the Windows volume, not the soundbar volume.

All videos can be turned up and turned down in "passthrough" - it is just Live TV and TV Recordings that can not.

This behavior does not occur in Windows Media Center. I'm not trying to call it better, but that I know it can work.

I could have something configured incorrectly in XBMC. It has a lot of audio settings. WMC has none.
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#5
This is not a PVR-specific issue. When using passthrough you can't change the volume from your computer. If it works for some other files you have then those do not have audio that is being passthroughed.
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#6
Also if you enable passthrough you have to check which codecs your soundbar can decode. Leaving them all unchecked makes no sense, if so you shouldn't enable passthrough at all.
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#7
(2014-07-15, 13:32)negge Wrote: This is not a PVR-specific issue. When using passthrough you can't change the volume from your computer. If it works for some other files you have then those do not have audio that is being passthroughed.

Please explain that to me then, because I can't really find much info about it for laymen like myself that do not understand a lot about codecs and audio drivers.

The sound on my television is disabled, because all audio is decoded by the soundbar.

The soundbar's volume is set to MAXIMUM, and pressing the Vol (+) and Vol (-) buttons on the media center remote cause the Volume Control in the Windows Task Bar to go Up or Down, accordingly.

That happens whether I have Passthrough enabled in XBMC or not.

(2014-07-15, 13:33)negge Wrote: Also if you enable passthrough you have to check which codecs your soundbar can decode. Leaving them all unchecked makes no sense, if so you shouldn't enable passthrough at all.

Which part was left unchecked? The wiki section only has screenshots. It doesn't explain to me what needs to be checked or how to determine what needs to be set. It's like they expect everyone to use trial and error.

I don't know how to tell what codecs my soundbar can decode. The reason I posted links to all of the items I use is so someone could show me how to learn what my soundbar can decode. Teach me to fish, and I can show others how to fish as well.

My Owners Manual has an Appendix of 1 page, titled "Trademarks and Licenses" that show Dolby Digital, DTS Digital Surround, and Bluetooth.

There is also no information in this manual about how many channels this soundbar has, so I don't really know what to select on that part of the interface either. It has 6 speakers on the bar itself, 3 on each side. 2 on each side are identical midrange looking devices, while the center on each side looks more like a tweeter.

It also has a remote subwoofer.

The closest I've been able to find is a "Sound Adjustment" page that talks about the different types of "built in" presets. "A Clear Voice setting is recommended when you watch the movie of 5.1 channel." There is also "Upscaler mode is available only to 2 channel sources."

I don't know if I should select 2 channel, 2.1, or 5.1. I'd never heard of 3.1, but it's in the list.

How do I tell what this soundbar does? I got it because it works with the TV and I do not have to have a separate receiver to process the sounds, not because it advertised a certain number of channels.

Also, it appears someone edited my original post.

I had links in that post to the exact Media PC, the exact television, and the exact soundbar that I have.

It was not so I could advertise their products, it was so others could help me better.
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#8
Perhaps this may help http://wiki.xbmc.org/index.php?title=Aud...tart_guide ?

Not knowing the capabilities of your soundbar, I'd suggest the settings for AVR-HDMI (no HD Audio). Also note that WASAPI is recommended over DirectSound.

Your post is also a little unclear about how everything interconnects, but I am guessing XBMC -> Soundbar -> TV all interconnected with HDMI ?
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#9
Passthrough means exactly that, a digital stream is passed through from the media file to the hdmi/spdif port direct to the sound creating device (in your case the soundbar) and the soundbar is responsible for decoding and then amplifying it, and sending to it's speakers.

By definition the computer (be it XBMC or the operating system) should not touch the audio at all, and that includes changing it's volume. (Changing the volume involves decoding the digital file and passing it through a filter and then re-encoding it. So you see, that's not passthrough).

So if you want passthrough (and it is generally accepted that specialised audio gear will decode audio codecs better than your PC can, so passthrough is good) then you need to control volume on the playback device (soundbar, amp etc).

You also need to be careful to only enable codecs that work with your sound gear, ie that are within it's decoding capability.

To know what the decoding capabilities of your soundbar are, look at the manual, or online specs, or ask in a user forum where other more knowledgeable users of that hardware may reside. However manufacturers do tend to fudge these things, in an effort to hype up in language they think sells their product, as opposed to language that might actually inform.

A few more points:

1. SPDIF (optical or coax audio cable) can at the most send two PCM channels (stereo), but it can also send compressed lossy codecs like AC3 (aka DD) and DTS as they "fit" within the bandwidth of stereo PCM. It cannot send HD audio like DTS-HD MA or Dolby TrueHD. At most AC3 or DTS will give you 5.1. A 5.1 audio TV show is likely to be AC3. I don't think anyone broadcasts DTS, but you'll find it on DVDs. HDMI on the other hand will carry any of the modern/current codecs.

2. Many TVs have HDMI in and SPDIF out to carry the audio out to an amp/soundbar. However many of them, for whatever reason, won't carry any more than stereo PCM, or sometimes AC3. This leads to disappointment, and is the reason that the correct connection method is

PC-->Amp-->TV (all over HDMI), or for an older amp with only SPDIF input.

PC-->TV
|--- >Amp
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#10
Quote:Which part was left unchecked? The wiki section only has screenshots. It doesn't explain to me what needs to be checked or how to determine what needs to be set. It's like they expect everyone to use trial and error.

When you enable passthrough there's a list of formats that you can check depending on whether your audio device supports them or not. The wiki assumes that if you don't know what any of that means you shouldn't enable passthrough.
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#11
I'm getting there! Smile

My audio goes in this order:


PC => HDMI => TV => SPDIF => SOUND BAR

where
  • PC = Intel Next Unit of Computing Kit, BOXDCCP847DYE
  • TV = LG 42LH50 42-Inch 1080p 120Hz Broadband LCD HDTV
  • SOUND BAR = LG NB3520A 300W Sound Bar with Wireless Subwoofer

With no links, maybe some moderator will not snip my information.

Disabling Passthrough seems to be working consistently with Live TV/Recorded TV and Videos off the NAS.

So, does anyone know why audio would be LOUDER when I play the same TV show or video in Windows Media Center? It is easily twice as loud as when I play anything on the same setup using XBMC. WMC does not have any settings for the audio, though, so I don't know what it is doing differently.
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#12
With the setup you have, there is no point at all enabling passthrough in XBMC. As nickr pointed out, 99.5% of TV's don't output 5.1 over optical out and in any case, your audio endpoint (the soundbar) is only 2.1 Therefore you should IMO, leave your channels set at 2.0 and leave passthrough disabled.

Regarding differing volumes - Whilst playing a video, you need to get the OSD (on screen display) by pressing m or enter on a keyboard, or OK on a remote. Navigate across the OSD until you reach the audio settings and select it. you will get this. You can adjust the 'volume amplification' and the actual volume until you are happy with the result. I believe XBMC remembers the settings on a per video basis, unless you choose 'set as default for all videos' at the bottom.
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