Certain AY8910 (or 8930?) VGM file plays only silence

[freq-mod]

8930test.zip the same file works in ZXTune.

[ValleyBell]

Can you post a WAV or MP3 of how it is supposed to sound?

All I can say right now is, that

1. libvgm doesn't support the AY8930 properly (it is treated as AY8910)
2. when being treated as AY8910, envelope shape 0xA0 does not work EDIT: I mean "generates no sound", which may be correct behaviour for a vanilla AY8910