How to disable the audio output at playing video slideshow

[loverhd]

Please help to get a solution of the following: I need to disable audio output while playing the video slideshow

The reason why it is needed:

I am planning to run on the win 7 desktop the mixed photo and video slideshow. And the xnview seems to be the best tool for this.
This photo-video slideshow will be played constantly, without interruption, all the time the computer is on.
But the computer is used not only for the photo-video slideshow watching, but also for the other activities. Including movies watching.
And therfore the sudden sound of the video-slideshow (ran on the desktop) while I am watching movie is something which is annoying and really stops me from using xnview at the moment for the photo-video slideshow run.

So what is needed - that xnview photo-video slideshow to be ran silently.
The very best case - to be able to toggle the sound of the photo-video slideshow on or off.

Obviously, the computer movie player, for example mpc-hc should be able to play movies with sound.
And this is the condition, which I at the moment do not know how to arrange. As I did not find how to specify the specific audio decoder, which is used in the xnView slideshow player, different from the one used in mpc-hc. Seems it take the same audiodecorder as the mpc-hc use. And if disable sound in this decoder, then mpc-hc will also be working without sound, and this is something which is bad for me in this solution.

Thanks a lot for your help in advance.

[xnview]

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