<< What's the 'Tunnel player'? >>
The 'Tunnel player' is a hardware accelerated media playback mechanism which is developed by libstagefright project.
It is included on some Qualcomm Snapdragon platform devices, such as Samsung Galaxy S4 (quad-core model).

The 'Tunnel player' has a side effect, if the Tunnel player is used, audio capturing process is bypassed, so Music Visualizer app can't obtain any audio data...
But I found a workaround and it's implemented on v 1.5.0!
Turn on 'Settings -> Misc. -> Avoid "Tunnel player"'

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