New Video & Audio plugin glitch

The test file here
when the MediaEngine or MediaSession playback method is checked has only 2 volume levels, loud and off.
not sure if it is a problem at your end or with the video file.

It’s probably an audio format that is bit-streamed to the output device, so the volume can’t be adjusted on the PC side, only muted.

You’ll see the same in other players, unless they decode the audio and output multichannel PCM.

it is only happening with the optical system. Works okay with DirectShow.

It’s down to the codecs whether that use bitstream or decode the audio on the PC side, if it’s a format the output device understands. Several DirectShow ones do it as well (or have options to do it, at least).