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captainys / TOWNSEMU

FM Towns Emulator "Tsugaru"
BSD 3-Clause "New" or "Revised" License
238 stars 17 forks source link

Scratchy / stuttery audio #76

Open prietveld opened 1 year ago

prietveld commented 1 year ago

I have been playing around with a ton of FM Towns images and Tsugaru settings, and while nearly everything plays perfectly fine with the odd issue here or there, almost all games have pretty bad / scratchy / stuttering sound for me.

CD audio plays back fine, but MIDI or digital audio is pretty poor. Could this be a host performance issue? I have a 1st gen (Nehalem) i7 @3.4GHz and am running Windows 10x64. Game performance seems fine otherwise.

I have tried emulating specific models, lowering or raising the emulated CPU speed, enabling and disabling FPU emulation and enabling and disabling 'Catch Up Real Time'. None of these have had a noticeable effect so far.

captainys commented 1 year ago

You may be experiencing the same situation as my PC. Turned out, a Win32 function, PeekMessage was taking more than 20 milliseconds and made it impossible for Tsugaru to fill the next segment. For this problem I don't have a solution. Closing Web browsers made it less irritating.

Another problem was although Direct Sound 8 document tells that write cursor is ahead of play cursor by 15 milliseconds, it was 20 milliseconds for my driver. I don't know if it is common or not. Tsugaru was supposed to have 5 milliseconds buffer to fill the next segment, but since it was not working as described on the document, Tsugaru had almost zero buffer.

I have added 10 milliseconds extra ring-buffer size so that Tsugaru has at least 10 milliseconds to fill the next segment even when the driver is not working as described in the Microsoft's official document. This eases the irritating noise a little bit.

If you can compile, please try the latest source, and let me know if it makes noise better.

prietveld commented 1 year ago

Thanks for your reply! I didn't have a browser (or much else) running in the background, but perhaps the buffer increase helps. Can we discount it simply being lack of CPU horsepower? First gen i7s might lack certain instruction sets of the later models? Anyway, I'd like to try it, but I don't have the environment nor the ready-to-go knowledge to compile from source. I'll give the next release a try as soon as it's out!

bcc2528 commented 1 year ago

I don't think the instruction set is relevant. Simply CPU performance potential. First generation Intel Core CPU have only about half the single threaded performance compared to the latest generation CPU, even if they were clocked identically.