BUG: wrong channel configuration disables Realtek SpeakerFill option

This is my scenario:

Using chrome/edge with command line parameter --try-supported-channel-layouts in order to make it output sound in (first available) stereo instead of the configured 5.1

This is because otherwise chromium outputs Youtube (or any other) stereo streams to the left front and right front channels of the available 5.1, leaving the audio empty on the others, and then Realtek SpeakerFill does not activate, since it works only when the detected stream is stereo.

This works correctly as long as FxSound is not used, and the music plays on all speakers.

When using FxSound and giving it the Speakers (Realtek (R) Audio) device as output, the SpeakerFill no longer works.

It seems that FxSound is upmixing the stereo track from the browser into 5.1 by simply playing the left and right of the stereo onto the left front and right front of the 5.1.

Another possibility is that FxSound declares to the browser that stereo is not supported and gives it a 5.1 channel configuration, so the --try-supported-channel-layouts defaults to 5.1 and the SpeakerFill option cannot activate.

Any suggestion if this is fixable? Some workaround?
If not can it be fixed in the future?

By the way a SpeakerFill option would be a great feature of FxSound by itself, so people don’t have to rely on drivers or other software.

Right now, unfortunately I cannot use FxSound, because this is a deal breaker.


Good evening Marino,
Sorry for your trouble.
As the first line of defense on this forum, I must humbly admit, that I know as good as nothing about 5.1 and other Surround setups, mainly since I’ve never had one myself.
All I can do, is redirect you to an already existing thread on the topic (see below) where I will add your concerns; and tag FxSound’s lead audio engineer on your behalf, to notify him of your issue.

Hi doolhoofd,

I don’t have a problem with surround sound itself. It works correctly for every app that outputs surround sound via FxSound.

My problem is if the app outputs stereo sound and my soundcard is configured in 5.1, then I woudl expect FxSOund to accept and forward such stream as stereo.

From what I see somewhere in the path via FxSound stereo is lost, making unavailable the soundcard feature to expand the stereo into surround, since it already is (but not upmixed).

Simply put: I lose the ability to listen to stereo music on all my speakers instead of just the front left and front right.


Okay. I edited my post in the previously mentioned thread.
Are you experiencing this issue with the Chrome and Edge browsers only?
You could perhaps try adding a browser extension to tweak your audio, e.g.:

I’m sure there are also similar ones for Edge out there.

To clarify I can listen to stereo on all my speakers if I upmix stereo into surround in the app itself.

For example in Winamp or Potplayer this is possible.

However for the browsers there is no “upmixing” functionality.
Plugins have no access to that, only access to effects, like boosting or equalization.

The only way to achieve the functionality I want is to force the browser to handshake stereo for the output, via the aforementioned command line switch, and subsequently enable the option in the sound card that expands stereo into surround, which works only when the soundcard is playing a stereo stream.

When using FxSound as the soundcard, it seems that this stereo from the browser either no longer works or the stereo sound when passing through FxSound is given in my default 5.1 channel configuration to the soundcard.

In both cases the soundcard is no longer able to upmix into surround.

This is how it works:

browser: stereo → soundcard sees stereo and is configured for 5.1 surround → soundcard upmixes to surround

One of these is true for FxSound:

browser: stereo → FxSound sees stereo → FxSound outputs surround to my soudncard without upmixing stereo
browser: asks FxSound for supported channel layouts → FxSound responds 5.1 before stereo or no stereo at all → from this point onward the soundcard can no longer upmix stereo, because we are already in surround.


Thanks for the explanation.
As I said though, I myself will not be able to further assist you with that issue.
I truly have no idea how to solve it, it exceeds my knowledge, both of browser audio technicalities, and of FxSound’s technicalities (I had no role in programming it, I’m just a mod).
We do have a lot of friendly users browsing the forum, who pitch in to solve problems from time to time; and I went ahead and tagged Vijay…
Afraid that’s basically all I can do for now.

Yes, thanks for your time, you were very polite.

I know this stuff can be tricky.

The main reason in this whole saga is the lack of functionality in the browsers.
If they had upmixing functionalities then FxSound would not be problematic anymore.

If FxSound talked to the browser in 5.1 and then output to the soundcard in 5.1 it would not matter anymore if the browser upmixed the stereo upfront onto all the 5.1 channels…


Have you tried Firefox and/or Opera?

I did not.
Good idea I will try Firefox.
For Opera there is no point since it is chromium based like Chrome and Edge.

1 Like

A list of 66 browsers ranked along with their advantages and disadvantages:

I just tried Firefox.
The behavior is identical.

Firefox does not upmix correctly when the sound is output via Javascript using AudioContext, but does when the stereo audio is played directly through the audio html element.

This is the bug filed and still unresolved: https://bugzilla.mozilla.org/show_bug.cgi?id=1434362

When not using FxSound the first scenario from the bug does not upmix in FF, but the second does.

However I have now confirmed that the problem lies in FxSound itself.
When FxSound is used neither of the two methods can upmix anymore.

I’m now pretty sure that FxSound does not respect the channel layout of the original audio stream when sending it to the soundcard.

I presume FxSound only talks to the soundcard with the configured channel layout of the soundcard, and simply maps the stereo streams to the front-left and front-right channels. leaving the others available but silent.


Also, I believe the free VLC Media Player has an option to stream online content directly inside the player, instead of in your browser.
So I’m guessing that if the issue is with streaming YouTube content, for example, you could use VLC to bypass the browser’s audio settings?
…Give me a second, I’ll do a search.

VLC Media Player allows us to easily stream videos from online sources. Online videos from video hosting sites like YouTube, DailyMotion, LiveLeak, etc. can be opened and played from VLC Media Player:

Yes I can stream youtube into PotPlayer as well and upmix in it.

However this complicates a lot if I want to change the music or advance playlists when using the browser…

For now my solution is to use Equalizer APO (https://sourceforge.net/projects/equalizerapo/), which allows to upmix and have effects and such like FxSound.

Please remove the previous paragraphs if it is against the Eula to link to competition.

I filed the bug here, in order to help FxSound improve.

For now I can manage myself.



P.S. I am also willing to help in coding if required.
FxSound has a nice GUI and would prefer to switch to it if it fit my needs.
If you need a guy that understands audio, understands programming (mostly C/C++/C#), you can contact me on my email.


It’s fine, I’ve recommended APO many times on the forum.

Right. :+1:
I hope you’ll hear from @bvijay soon.
Thank you for supplying detailed information on the issue; and, my apologies, for my ignorance and inability to help.

Went ahead and forwarded this to the FxSound team. :slight_smile: Thanks!

1 Like

This is off-topic, but…
I know a nifty stereo-widening VST plugin compatible with APO, co-created by the legendary psytrance act Infected Mushroom…
It’s called Wider, and you can download it for free here: