So, just like we (the Stella team) posted a thread about improving TIA graphics emulation, we now also want to start on TIA sound emulation. This work is documented at https://github.com/s...tella/issues/80.
Last year, some code was donated to Stella from crispy (Chris Brenner) from his FPGA work. At the time the TIA emulation core wasn't properly structured to make use of it, but now it is. As a result, Christian Speckner (DirtyHairy) has ported the code to Stellerator. The initial results are very good; many test ROMs that didn't sound quite correct are now properly emulated.
So now work begins on refining this code, and porting to Stella. What we need are test cases. That is, ROMs that illustrate where the current sound emulation is inaccurate/incorrect. We'd like you to test in Stellerator and in Stella 5, and (potentially) with new test builds of Stella as they become available. Please try to be as specific as possible when describing the issues (keeping in mind that it's hard to 'describe' sound). I'll start with some ROMs we already know about, in no particular order:
- phaser06: correct in Stellerator, in Stella 5 the sound is 'idealized' and sounds much nicer than it should
- tremolo: correct in Stellerator, left and right channels are properly 'mixed' and interfere with each other
- E.T.: sounds much better in Stellerator
- Ms. Pac-man: correct in Stellerator, there is now distortion from the analog mixing of left/right channels. In Stella 5 the sounds is 'better', but it is idealized and not like a real console.
Remember, just like when we were improving the TIA graphics emulation, the more test ROMs and cases we get, the better the results. So get testing