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kode54 / Game_Music_Emu

Game Music Emu - Multi-purpose console music emulator and player library
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YM2608 rhythm channel distortion #17

Open mmontag opened 5 years ago

mmontag commented 5 years ago

Hi @kode54 , I'm getting some severe distortion on the YM2608 rhythm channel (I think?). Is this something you're able to reproduce? I know these cores come from MAME.

see Grounseed tracks for example: https://mmontag.github.io/chip-player-js/?q=grounseed&play=VGM+Rips/Grounseed_(NEC_PC-9801%2C_OPNA)/12+F.N.+%5BFive+Knights%5D.vgz

mmontag commented 5 years ago

Looking into this a bit more, I believe it's just a 16 bit integer overflow clipping distortion, after summing all the SSG (psg) channels with the PCM and FM channels. Nothing to do with the ADPCM rhythm channels in particular.

YM2608 chip has 16 total channels so they need a lot of headroom to avoid clipping. I will have a look at the VGMPlay branch and try to find the appropriate gain levels for mixing all these channels.