#1086 6581/8580 filter hard-clipping

[ltx128]

Hi,

On some tunes by Alien/WOW the ReSID filter sounds like it's hard-clipping or overflowing. This occurs on both 6581 and 8580. I've attached a recording from GTK3VICE r35872 to this ticket: FS_GTKVICE_r35872_6581_15s.ogg

This wasn't a problem on 8580 until the last couple of filter patches. Looking at the overall envelope of Freak Show this issue appears on the 8580 setting around r32576. Fiddling around with the settings choosing the 8580D setting fixes it, so this is probably related to the other filter bugs. This issue is also audible on the 6581 setting though. The hard-clipping occured on every subversion revision using 6581 I tried going back a couple of years. It doesn't occur on ReSIDfp.

Example SIDs where the issue can be heard:
http://hvsc.csdb.dk/MUSICIANS/A/Alien_WOW/Freak_Show.sid
http://hvsc.csdb.dk/MUSICIANS/A/Alien_WOW/Evidence.sid
http://hvsc.csdb.dk/MUSICIANS/A/Alien_WOW/Imaginary_Friend.sid
http://hvsc.csdb.dk/MUSICIANS/A/Alien_WOW/Revolution.sid

SOASC (Real C64) Links:
http://teamarchive1.fnf.archive.org/OAKVALLEY/soamc/soasc/hvsc/049/MUSICIANS/A/Alien_WOW/Freak_Show_T01.sid_CSG8580R5.mp3
http://teamarchive1.fnf.archive.org/OAKVALLEY/soamc/soasc/hvsc/049/MUSICIANS/A/Alien_WOW/Freak_Show_T01.sid_MOS6581R2.mp3
http://teamarchive1.fnf.archive.org/OAKVALLEY/soamc/soasc/hvsc/049/MUSICIANS/A/Alien_WOW/Freak_Show_T01.sid_MOS6581R4.mp3

[ltx128]

Attached some other recordings from real SID chips.