Dolby 5.1 mystery

Post Reply
sjr56stn

Posts: 46
Joined: Tue Mar 03, 2015 4:49 pm
Location:

HTPC Specs: Show details

Dolby 5.1 mystery

#1

Post by sjr56stn » Tue Nov 26, 2019 12:45 pm

I have a Windows 7 64bit media PC, which includes a Saphire HD6450 video card, which has AMD High Definition HDMI Audio. This is connected to my TV by HDMI cable, and an optical cable goes from the TV to my Logitech sound system. This always used to provide Dolby 5.1 true surround sound when fed with an appropriate recorded or live TV or DVD source, but something has changed! It took a while to notice this problem, but I suspect a Windows update sometime back might have caused it.
The Windows sound applet now just reports 2-channel stereo for the AMD HDMI audio, but amazingly WMC drives all six speakers when you go to set up speakers and click the test button. But it reverts to stereo as soon as you leave the setup speakers dialogue.
I have updated the HD6450 driver, but it makes no difference to the problem. (And I have then rolled back this driver because it seems to make WMC unstable.)
I have seen quite a lot of stuff online about Win 7 bugs in the sound, but none of the fixes I have tried seen seem to work for me.
It seems to me that Windows 7 only sees a 2-channel sound system, but WMC knows the trick to switch on all the 6 channels but only when you are in the setup dialogue!
Any ideas?
Steve

PS - My Asus P7P55-M motherboard includes Via Technologies sound, but I have disabled this to avoid confusion. (I have tried disabling it in Windows, even disabling it in the BIOS setup, but this makes no difference to my problem.)

User avatar
StinkyImp

Posts: 211
Joined: Thu May 11, 2017 7:53 pm
Location:

HTPC Specs: Show details

#2

Post by StinkyImp » Tue Nov 26, 2019 3:34 pm

sjr56stn wrote:
Tue Nov 26, 2019 12:45 pm
I have a Windows 7 64bit media PC...
Worth 2 cents (or less).

Some years ago I was trying to hook up Sony ARC to a Yamaha sound system. After a few hours of struggling with it, I gave up.

Since then (and on a number of systems) I have used the following cable configuration.

For WMC use:
  • For video -> HDMI cable from PC to TV (no audio).
  • For audio -> Sound outputs on PC to inputs on sound system.
For TV only (from cable or antenna):
  • For audio -> Optical cable from TV to optical input on sound system.
This has always worked for me to provide 5.1 through my receiver even when the signal is in stereo. In those cases it may not be true Dolby, but it's better than stereo from the TV speakers.

sjr56stn

Posts: 46
Joined: Tue Mar 03, 2015 4:49 pm
Location:

HTPC Specs: Show details

#3

Post by sjr56stn » Tue Nov 26, 2019 4:12 pm

Yes, I can get surround sound from the PC if I use the VIA Technologies HD audio and the analogue cables straight from the PC to the sound system, but then I have to switch the sound system to optical input when I want to just watch TV in 5.1.
That is annoying and, as I said, it used to work fine!

sjr56stn

Posts: 46
Joined: Tue Mar 03, 2015 4:49 pm
Location:

HTPC Specs: Show details

#4

Post by sjr56stn » Tue Nov 26, 2019 4:25 pm

.. and I really would like to understand how WMC is able to drive the 6 speakers when in the speaker setup menu, when Windows insists that the HDMI audio has only two channels!

dmagerl

Posts: 372
Joined: Mon Jun 06, 2011 9:16 pm
Location:

HTPC Specs: Show details

#5

Post by dmagerl » Tue Nov 26, 2019 4:34 pm

Is the auto volume feature enabled in WMC? That converts 5.1 to 2 channel.

sjr56stn

Posts: 46
Joined: Tue Mar 03, 2015 4:49 pm
Location:

HTPC Specs: Show details

#6

Post by sjr56stn » Tue Nov 26, 2019 5:21 pm

No, auto volume is not set and, as I said, WMC can drive all 6 channels in the speaker setup dialog. It is Windows that insists that there are only two channels.

User avatar
Shark007

Posts: 187
Joined: Thu Feb 07, 2013 5:20 am
Location: Ontario, Canada

HTPC Specs: Show details

#7

Post by Shark007 » Tue Nov 26, 2019 6:25 pm

The TV only has 2 speakers therefore the HDMI connected to the TV sees 2 channels.
The TV (no TV, not just your TV) is NOT capable of passing a multichannel signal from the PC over HDMI to the optical out of the TV.

When using the TV without the PC as the source, you can get multichannel audio sent to the soundbar if the channel has 5.1 audio
Retain your sanity, use Shark007 Codecs

sjr56stn

Posts: 46
Joined: Tue Mar 03, 2015 4:49 pm
Location:

HTPC Specs: Show details

#8

Post by sjr56stn » Tue Nov 26, 2019 6:43 pm

Thanks Shark007, but it used to work, and WMC can send 6 channel through the HDMI and TV when in the Speaker setup dialog, AND the TV is perfectly capable of receiving and passing through 6 channel digital audio.
If you are saying that something has changed in the Windows audio driver to force 2 channels when it recognises a TV on the end of the HDMI, then that is certainly possible. If so, WMC whilst in the speaker setup dialog, is ignoring this 2-channel restriction.

User avatar
Shark007

Posts: 187
Joined: Thu Feb 07, 2013 5:20 am
Location: Ontario, Canada

HTPC Specs: Show details

#9

Post by Shark007 » Wed Nov 27, 2019 2:15 pm

Shark007 wrote:
Tue Nov 26, 2019 6:25 pm
The TV (no TV, not just your TV) is NOT capable of passing a multichannel signal from the PC over HDMI to the optical out of the TV.
I am not saying something has changed.
I am saying that you are mistakenly believing this worked for you in the past.

For this to work, you would need a direct connection from the PC to the Soundbar.
Retain your sanity, use Shark007 Codecs

sjr56stn

Posts: 46
Joined: Tue Mar 03, 2015 4:49 pm
Location:

HTPC Specs: Show details

#10

Post by sjr56stn » Wed Nov 27, 2019 2:38 pm

Oh! I am an unreliable witness!
We have a number of music concert TV recordings that we used to watch in 5.1. Now we cannot do so.
We have a number of DVDs and blu-rays that we used to watch in 5.1. Now we cannot do so.
I can assure you that something changed a few months ago.

User avatar
Shark007

Posts: 187
Joined: Thu Feb 07, 2013 5:20 am
Location: Ontario, Canada

HTPC Specs: Show details

#11

Post by Shark007 » Wed Nov 27, 2019 3:39 pm

I am somewhat aged and my information can be aged also.
So, I went and did some searching to refresh my knowledge...
This page is quite helpful for your topic - https://www.rtings.com/tv/tests/inputs/ ... assthrough
"Dolby Digital 5.1 passthrough via digital optical" is a heading of interest on that page.

Bottomline as far as I can tell is that it is a feature that your TV must support.
Retain your sanity, use Shark007 Codecs

sjr56stn

Posts: 46
Joined: Tue Mar 03, 2015 4:49 pm
Location:

HTPC Specs: Show details

#12

Post by sjr56stn » Wed Nov 27, 2019 4:53 pm

Shark007 - Thanks for the interesting link. I am also somewhat aged (I was learning FORTRAN in 1966), but I shall study it and try to understand it!

sjr56stn

Posts: 46
Joined: Tue Mar 03, 2015 4:49 pm
Location:

HTPC Specs: Show details

#13

Post by sjr56stn » Wed Nov 27, 2019 5:17 pm

Out LG TV is some 7 years old, and does not appear on the list, but the manual and specification imply that it will pass a digital audio signal through to the optical audio output. All the TVs that are listed seem to pass the Dolby 5.1 through.
And (sorry to be boring) as I keep saying, it used to work! And it STILL WORKS when clicking the test button in the WMC speaker set-up dialog. The 6 speakers sound in sequence, and the little display on the sound system shows Dolby digital. So that proves that the TV is passing the Dolby 5.1 through to the sound system. It just switches back to stereo as soon as you leave that WMC speaker setup dialog.
This has just got to be a Windows 7 issue.

User avatar
StinkyImp

Posts: 211
Joined: Thu May 11, 2017 7:53 pm
Location:

HTPC Specs: Show details

#14

Post by StinkyImp » Thu Nov 28, 2019 3:55 pm

sjr56stn wrote:
Wed Nov 27, 2019 4:53 pm
I am also somewhat aged (I was learning FORTRAN in 1966)...
Thanks for making me feel young again! I was learning FORTRAN and COBOL in the early 80s and have been feeling the ravages of time recently. ;)

You said that it worked previously. If you haven't made any hardware or cabling changes, have you searched the Event Log for the past few months to see if you have any errors or warnings that might give you any clues as to what may have happened?

sjr56stn

Posts: 46
Joined: Tue Mar 03, 2015 4:49 pm
Location:

HTPC Specs: Show details

#15

Post by sjr56stn » Thu Nov 28, 2019 4:35 pm

StinkyImp - No I haven't scrolled through the event log. Cannot do that just at the moment. But the crucial point is that the WMC speaker dialog and test button can make it work now! It just reverts to Stereo as soon as you leave the dialog. Perhaps I should use the speaker test button and then immediately look at the event log. I will try that later.

sjr56stn

Posts: 46
Joined: Tue Mar 03, 2015 4:49 pm
Location:

HTPC Specs: Show details

#16

Post by sjr56stn » Sun Dec 08, 2019 4:04 pm

I had a bit of a breakthrough thanks to the film Madagascar 2 which was being shown on BBC1 this afternoon. I discovered that if I watched or recorded this program using my Freesat S2 tuner I received the Dolby 5.1 surround sound, but if I switched over to my Freeview T2 tuners, then I received only stereo. I know BBC was transmitting it in 5.1 on the Freeview terrestrial channels because I could watch it and listen to it in 5.1 on my TV.
I tried updating the drivers on my T2 tuner card, but then the HD channel didn’t work at all, so I rolled it back.
But the interesting thing is that, as with the WMC speaker setup dialog, WMC is able to send Dolby 5.1 to the HDMI cable to the TV, even though the Sound applet on Windows 7 reports only 2 channels. Is WMC somehow bypassing the Win 7 High Definition sound driver? And if so, can I persuade other software (I use VLC to play blu-ray discs) to perform the same trick?

PS - The tuner card that is giving me Dolby 5.1 on the satellite S2 is a Hauppauge, Wintv Hvr 4400 (dual tuner DVD-T + DVD-S2), whilst the terrestrial tuner card that is not is a TBS 6280 (dual tuner 2x DVD-T2).

Space

Posts: 1597
Joined: Sun Jun 02, 2013 9:44 pm
Location:

HTPC Specs: Show details

#17

Post by Space » Mon Dec 09, 2019 9:50 am

Not sure of the answer to your question, but I do know that the sound that is sent via HDMI is controlled by the video drivers (not the sound drivers) and is separate from any sound card you may have (Realtek, Conexant, etc.)

So to update the HDMI sound drivers you would actually have to update your video drivers.

unclebun

Posts: 47
Joined: Sun Jul 09, 2017 11:06 pm
Location:

HTPC Specs: Show details

#18

Post by unclebun » Mon Dec 09, 2019 2:28 pm

Space wrote:
Mon Dec 09, 2019 9:50 am
Not sure of the answer to your question, but I do know that the sound that is sent via HDMI is controlled by the video drivers (not the sound drivers) and is separate from any sound card you may have (Realtek, Conexant, etc.)

So to update the HDMI sound drivers you would actually have to update your video drivers.
Along those lines, check to see if a Windows Update optional update substituted generic Microsoft-supplied drivers for your video card over the manufacturer supplied driver.

sjr56stn

Posts: 46
Joined: Tue Mar 03, 2015 4:49 pm
Location:

HTPC Specs: Show details

#19

Post by sjr56stn » Tue Dec 10, 2019 8:34 am

The video card driver is from the card manufacturer AMD. It is not the most up-to-date version. I have tried the mostup-to-date driver, and it made no difference to the Dolby 5.1 problem, but WMC became a bit unstable, so I rolled it back.
And I don't see how it can be a problem with the video card driver if I can get Dolby 5.1 when the program is recorded on the satellite tuner, but not if it is recorded on one of the terrestrial tuners.

sjr56stn

Posts: 46
Joined: Tue Mar 03, 2015 4:49 pm
Location:

HTPC Specs: Show details

#20

Post by sjr56stn » Tue Dec 10, 2019 8:52 am

I think there are two separate issues here.

Firstly the fact that Windows only reports a two channel HD sound system. I accept that this could be a video card driver issue. This is also the issue that presumably prevents other software (such as VLC blu-ray) from sending 5.1 to the HDMI cable. I have tried updating the video driver but it didn’t change anything, except make WMC unstable.

The second issue is that WMC can clearly ‘bypass’ this problem, and can successfully deliver Dolby 5.1 to the TV and the sound system. The fact that this only works when I record TV using my satellite S2 tuner, and not when I use one of the terrestrial T2 tuners, indicates that there may be a problem with the driver for the T2 tuner card. I have tried updating this tuner driver but the result is that many of my TV stations stop working. I suppose a complete TV retune might fix this, but I have baulked at this for the moment, so I rolled back the tuner driver. I might try this again, but only after I have made another C: image, so that I can easily revert if all goes to rats**t!

Post Reply