Author Topic: Irem M92 Frame/Audio Stuttering  (Read 279 times)

Offline retroFuture

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Irem M92 Frame/Audio Stuttering
« on: February 27, 2020, 04:10:13 AM »
Hello  :smilie:
For my first post, I'd like to contribute by reporting very minor frame/audio stuttering on Irem M92 games.

So far I've tested:
R-Type Leo
Lethal Thunder
Blade Master
In The Hunt
Hook
Mystic Riders


I haven't tested all M92 games, but so far, the stuttering, whilst minor, is consistent across all the games I've tested.
I am running FBNeo through Lakka 2.3.2 on a RPi4 2Gb with active and passive cooling
« Last Edit: February 27, 2020, 04:13:00 AM by retroFuture »

Offline barbudreadmon

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Re: Irem M92 Frame/Audio Stuttering
« Reply #1 on: February 27, 2020, 06:25:03 AM »
Maybe the pi4 is too slow to run our m92 driver ? Setting frameskip to 1 in core options remove the stuttering ?

Offline retroFuture

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Re: Irem M92 Frame/Audio Stuttering
« Reply #2 on: February 27, 2020, 07:41:02 AM »
I was wondering if that was the case. I think it should be fast enough, but I will try your suggestion. The M92 games seem to run smoothly on the MAMe 2003 Plus core, but that may be comparing apples to oranges. Just thought I should mention it in case it is a bug.

Offline barbudreadmon

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Re: Irem M92 Frame/Audio Stuttering
« Reply #3 on: February 27, 2020, 08:13:37 AM »
The M92 games seem to run smoothly on the MAMe 2003 Plus core, but that may be comparing apples to oranges.

Yes, it's not a fair comparison, dink started fixing irem m92 emulation in 2014, prior to that it was really approximate (for both fba & mame).

Offline retroFuture

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Re: Irem M92 Frame/Audio Stuttering
« Reply #4 on: February 27, 2020, 08:23:48 AM »
I suspected that the FB/MAME comparison my be faulty. Anyway, I also wanted to ask if there is a dedicated thread for bug reporting or if it's preferable for me to make a post for each bug.

Offline Arcadez

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Re: Irem M92 Frame/Audio Stuttering
« Reply #5 on: February 27, 2020, 09:35:17 AM »
I suspected that the FB/MAME comparison my be faulty. Anyway, I also wanted to ask if there is a dedicated thread for bug reporting or if it's preferable for me to make a post for each bug.

It's not a bug more a case of the system your using does not have the power under the hood to emulate these games fully
Irem 92 and 107 games were state of the art at the time, they fire some nifty graphical effects via raster irqlines which
constantly update every other frame or so.

It's these raster updates which can cause the games to have performance issues on lesser hardware, we had the same problems on the
xbox with Irem 92/107 using our FBN port, so we tended to use the older MAME cores as since the games perform better in those cores
it tends to even out the fps.

You can of course disable the raster updates if you know how but that is a whole different story :)

« Last Edit: February 27, 2020, 09:46:13 AM by Arcadez »

Offline Arcadez

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Re: Irem M92 Frame/Audio Stuttering
« Reply #6 on: February 27, 2020, 09:45:25 AM »
Yes, it's not a fair comparison, dink started fixing irem m92 emulation in 2014, prior to that it was really approximate (for both fba & mame).

The emulation of the Irem 90/92/107 games is pretty good in MAME2003-Plus, we updated the opcodes and the Iremga20 soundcore to latest
MAME netting us a whole host of graphical and sound improvements, we also did a few more graphical fixes on a per game basis added in some
more speedhacks then got Air Assault / Fire Barrel, Risky Challenge and Undercover Cops (Alpha Renewal Version) playable.

Im quite proud of the work we did on those drivers  :wink:
« Last Edit: February 27, 2020, 09:56:26 AM by Arcadez »

Offline barbudreadmon

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Re: Irem M92 Frame/Audio Stuttering
« Reply #7 on: February 27, 2020, 10:18:07 AM »
The emulation of the Irem 90/92/107 games is pretty good in MAME2003-Plus, we updated the opcodes and the Iremga20 soundcore to latest
MAME netting us a whole host of graphical and sound improvements, we also did a few more graphical fixes on a per game basis added in some
more speedhacks then got Air Assault / Fire Barrel, Risky Challenge and Undercover Cops (Alpha Renewal Version) playable.

Im quite proud of the work we did on those drivers  :wink:
Nice, so everything besides the raster should be ok ?
Which makes me remember that you showed me how to disable those, i'll give a try to implementing a speedhack dips for those irem boards soon.

Edit : turns out disabling the raster doesn't seem to improve framerate by much
« Last Edit: February 27, 2020, 02:06:18 PM by barbudreadmon »

Offline barbudreadmon

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Re: Irem M92 Frame/Audio Stuttering
« Reply #8 on: February 27, 2020, 02:25:34 PM »
@retroFuture You wouldn't happen to have some setting eating additional cpu ? Like retroarch's readahead/rewind or a "cpu clock" value above 100% in core options ? rtypeleo is close enough to running full speed on my pi3b+ (around 57fps, will run at a rather stable 60fps if i set "cpu clock" to 80-85%), it seems weird it wouldn't on pi4, which is supposed to be a big cpu upgrade.

Offline Arcadez

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Re: Irem M92 Frame/Audio Stuttering
« Reply #9 on: February 27, 2020, 07:07:01 PM »
Nice, so everything besides the raster should be ok ?
Which makes me remember that you showed me how to disable those, i'll give a try to implementing a speedhack dips for those irem boards soon.

Edit : turns out disabling the raster doesn't seem to improve framerate by much

Yeah on the xbox we got a wee boost up by disabling the raster lines nothing earth shattering right enough, but it did make a difference
with some of the games, BTW the main reason the M92/107 games are faster in the older cores is due to most of them having per game speedups
R-Type Leo actually has two if you count the graphical hack as well.

Offline retroFuture

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Re: Irem M92 Frame/Audio Stuttering
« Reply #10 on: February 28, 2020, 02:58:24 AM »
@retroFuture You wouldn't happen to have some setting eating additional cpu ? Like retroarch's readahead/rewind or a "cpu clock" value above 100% in core options ?
I disabled runahead and have never used rewind. I think the CPU clock is set to default, but I have increased it before when running Metal Slug games to eliminate the (inherent) slowdown. I may have forgotten to set it back to default when running the M92 roms.
« Last Edit: February 28, 2020, 03:05:10 AM by retroFuture »

Offline barbudreadmon

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Re: Irem M92 Frame/Audio Stuttering
« Reply #11 on: February 28, 2020, 03:41:53 AM »
I have increased it before when running Metal Slug games to eliminate the (inherent) slowdown.

There is a no-slowdown version of metal slug 2, the romset is called mslug2t. I don't recommend increasing cpu clock, and if you do it anyway, do it on a per-game basis through overrides, because it's causing more issues than it solves.

Offline retroFuture

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Re: Irem M92 Frame/Audio Stuttering
« Reply #12 on: February 28, 2020, 03:46:38 AM »
There is a no-slowdown version of metal slug 2, the romset is called mslug2t. I don't recommend increasing cpu clock, and if you do it anyway, do it on a per-game basis through overrides, because it's causing more issues than it solves.

I did not know that. Your advice is much appreciated. Really wish I'd joined this forum sooner.