The loss of generator is always negative.

[manhongxiang]

It seems that it needs a minus sign. But after adding a minus sign to g_loss, it does a bad job and generate weird MIDI after 400 epochs training.

[manhongxiang]

g_loss becomes very low (about 0.003) in less than 10 epochs, then it slowly reduces to 0.001. Maybe generator learned very little thing, so it generates weird MIDI.