MiSTer FPGA Forum

Hey all, I've run into a strange audio glitch with a specific game on the PC Engine CD/TurboGrafx CD core:

When starting up the game Tanjou Debut, the opening sequence that automatically plays will have choppy voice audio which seems to cause an overall core slowdown (if I try and open up the menu when this happens, it will be very slow/unresponsive)
In addition to the audio issues, sometimes the character sprites will disappear altogether and/or the screen will just freeze up on whatever the last one loaded was - in this case the audio will behave normally and no slowdown will occur. This isn't 100% consistent though, so sometimes it'll just be glitchy audio + slowdown all the way to the end, but other times the video will seem to freeze, but the audio will play without an issue after that.

I'm using my own dump of the game, which was made via TurboRip (so cue+wav+ISO), and have tried making a new rip to double-check + tested a completely different dump from archive.org (which was cue+bin) and can confirm the issue occured in all cases.

I have the latest version of the core (22.03.26) + MiSTer (V220413) installed, but I've also tried out some older core versions (including the 2nd most recent from 22.02.12, + a random selection of 4 or 5 2021 releases) with no change. I have more or less default settings (the only things I've changed are enabling the arcade card + auto save), so CD Seek is Normal etc.. + am using the Japanese Super CD-ROM v3.00 BIOS.
(Also 128MB RAM expansion installed if that matters)

Video of this behavior below. In this particular instance, the first character shows up and sounds fine, but the 2nd through 4th have the choppy audio issue. The sprites for the characters after that disappear altogether, but their voice audio works fine.

I have taken a look at this and can verify:
a) Choppy sound
b) This choppy sound is caused by significant log output from Main_MiSTer, which I can file a bug for, and can correct.

I was not able to verify the missing sprites later in the sequence, but let's first assume that this is somehow related to the first issue, and retest after a correction for that is available.

I've fixed the choppy sound and submitted a pull request.

The "missing sprites" turns out to be a separate issue - it looks like the core is waiting for a response or an interrupt of some kind.
I will file this separately (it likely will need time to get solved).

Looks related to whether Head seek time is on.
While this is being examined, you may want to play that particular scene with Head Seek = Fast.

After a while I was unable to reproduce the "hang" scenario.
After the next Main_MiSTer release (which will include the choppy audio fix), please retest.

Awesome, thanks so much!!!
I'll keep an eye out for the next release and see what happens from there.

Just installed the new MiSTer release (20220511) and it looks like the issue has been resolved!
I let the opening sequence play all the way through a few times and it played perfectly every time; I didn't observe any audio stuttering, or freezing/missing sprites.

Thanks again!!!

I'm glad it works for you. I did see it stall a few times, but it's different each time.
I think I understand the mechanism, but I don't have a total solution yet. But it's good that the issue is now only intermittent.