60 fps patch causes cutscene audio desync

[SilentHeII]

This is most noticeable during the cutscene where York meets Emily and George. The animations falls behind the audio.

[LittleBitUA]

Confirmed and fixed in 1.1.

Root cause: the 60 FPS patch pinned the game's logic tick to exactly 1/60 s regardless of the real frame time. Every frame that took longer than 16.7 ms (Windows sleep granularity alone adds a millisecond or two, and cutscenes with depth of field are heavier) advanced game time by less than real time, while the streamed audio kept real time - so over a long scene the animation drifted behind the voices.

1.1 derives the tick from the measured frame time (a 50 FPS frame advances 1.2 ticks, a 60 FPS frame exactly 1.0) and the runtime now sleeps with a high-resolution timer so the game's own limiter actually holds 16.7 ms. The Emily/George scene stays in sync here; please reopen if you still see drift somewhere.

[LittleBitUA]

Fixed in 1.1.

[SilentHeII]

It's still desynced, but in the opposite direction. The cutscene audio is now falling behind the animation.

[LittleBitUA]

Thanks for re-testing - you are right, and the direction tells me exactly what it is.

1.1 derives the tick from the measured frame time, but I clamped it to never go below 1.0 (a frame is never "less than one 60 Hz tick"). The game's own limiter releases frames on a millisecond-granularity timer, so a lot of frames come in at 16.0 ms instead of 16.67 ms: the real tick for those is 0.96, it gets rounded up to 1.0, and the game runs about 4 % faster than real time. Over a long scene that is the animation getting ahead of the voices - the opposite drift from 1.0.

Fix (next update): the lower clamp is a setting now, dp_60fps_tick_min, default 0.5, so the tick follows real time both ways. Setting it back to 1.0 gives the 1.1 behaviour if anything in the game turns out to dislike sub-1.0 ticks.

I'll ping here when the build with it is up; if you can re-run the same scene then, that would be the best confirmation.

[LittleBitUA]

1.2 is up with the tick fix: https://github.com/LittleBitUA/DPRecomp/releases/tag/v1.2.0 (the launcher's Update button installs it in place). The lower clamp is dp_60fps_tick_min in deadlyprem.toml, default 0.5. If the Emily/George scene stays in sync for you now, I'll close this; if it drifts either way, please say which direction.

[SilentHeII]

The audio is still behind animation. I'd almost argue it's almost subtly worse.

[SilentHeII]

I'm testing it on other cutscenes and it appears to work. My new theory is that maybe it's related to performance? If the game can't hit 60fps consistently maybe it lags? Since that cutscene is outside and the game is just a programming mess, maybe it can't keep up? Other cutscenes sync fine it seems. Looking at the Ushah morgue scene again before the audio mutes. lol

[LittleBitUA]

Yeah, so... my bad. The 1.2 "fix" was a no-op and I just found out why.

The tick clamp I added (dp_60fps_tick_min = 0.5) does get applied, but two instructions later the game clamps the tick to >= 1.0 itself (there's a literal 1.0f sitting in the XEX's constant pool right there). So my 0.96 goes in, the game rounds it back up to 1.0, and 1.2 behaves exactly like 1.1. That's your "still behind, maybe subtly worse" - it's the same build as far as this bug is concerned. Should have checked the instructions after the hook instead of just the one I patched.

Next build skips the game's clamp too, and I've also put a stats line in the log (frame times + how far game time runs from real time) so this stops being guesswork. Two things from you would help a lot when it's up: does the Emily/George scene stay in sync with 60 FPS off (Graphics → 60 FPS in the launcher), and does the desync grow over the scene or is it a constant offset from the start? Those two answers pretty much decide whether the remaining drift is the tick or the audio side.

[SilentHeII]

It stays in sync without the 60fps patch.

[DexgamingX]

Just fyi, I've been playing the game through Xbox One with the official backwards compatibility and the audio desync is still present in a lot of the cutscenes in the official release of the game, so I don't think this is specifically an issue with the recomp.

[LittleBitUA]

Good, that settles it: it's the 60 FPS path, nothing on the audio side.

The proper fix is built and verified: with the game's own >= 1.0 clamp skipped, game time tracks real time to four decimal places on my end (it used to run about half a percent fast per frame of jitter, which over a five-minute scene is a second or two - and more on a machine that jitters more). It'll be in the next build, I'll ping here when it's up so you can run the Emily/George scene again.

@DexgamingX good to know, thanks. There is some drift in the original on real hardware in a few scenes, yes - but what SilentHeII is seeing scales with the 60 FPS patch and disappears at 30, so this part is ours. Once the fix is out, whatever is left should be the game's own.