Screen Resolution & Audio Latency

[Weaselrama]

Hello. This is my first post to the EAB board!

I'm going to copy a post I wrote for the Facebook "The Amiga Computer" group. I've also emailed Toni Wilen with this issue via EAB email.

This post was part of a series I have been writing about.

The post regards my experience in FS-UAE with audio latency on higher screen resolutions. I had achieved 1920 x 1080 by placing the following in the advanced parameters window:

fullscreen_height = 1080
fullscreen_width = 1920

This passes the resolution to P96 in Screenmodes. I'm running a MBP (2017 13") to an LG 4K monitor. FS-UAE is in A4000 mode.

Here is the post in its entirety. It explains the audio latency issue I've been experiencing:

"Hello all. If you'e followed my posts you know I've been modding OS 3.9 running in FS-UAE. My last post I happily proclaimed I had achieved 1920 x 1080 resolution thanks to a setting entered into FS-UAE's advanced properties which passes new resolutions to P96. I loudly proclaimed that except for a few tweaks, victory!

Boy was I wrong. I ran Eagleplayer and AMPlifier several times and brought up a few things and thought "Well, that's that." That is, until I earnestly sat back to enjoy the fruits of my labor with an evening of music and getting back to a document I was writing in Wordworth 7. That's where the trouble started. The more the MODs or Mp3s played, the worse the latency until the audio crawled.

I tried everything, remembering always that more RAM was never the solution. More RAM = greater Macbook CPU usage. So I tried fiddling with some FS-UAE audio cache and video sync tweaks I found online. Nope.

I noticed that I could bring up Protracker 3.61 and the latency disappeared completely. Then it hit me - lower the screen resolution - the very last thing I wanted to do.

It almost tasted of defeat, that is, until I lowered the resolution to 1280 x 1024, lower than my original WB 3.1 resolution of 1344 x 1080. I couldn't make Eagleplayer stutter no matter what I tried. No latency in AMPlifier until I opened a ridiculous number of windows and apps.

I have cleaner audio than I've ever had during the entire time I've been playing with FS-UAE. I learned that the rule which states NEVER build more machine than you need in UAE includes running hi-def resolutions that bog down the Mac's processor.

Now I can listen to music uninterrupted while I multitask and never miss a beat. I should add that the MOD I tested through-out this process was Guitarslinger by Jogeir, one of the most complicated, processor intensive MODs there is and it now plays in EaglePlayer as smoothly as it does in Protracker while I'm working.

NOTE: I went back and tested this with my 3.1 installation which uses MagicWB. I ran it at 1920 x 1080 and 1344 x 1080 and experienced the same latency issues. So the addition of the Mason icon sets had no effect whatsoever - screen resolution was the culprit."

I had some good comments from other members. It was suggested this was a bug because GPU and screen resolutions should not affect audio.

Has anyone else experienced audio latency issues running FS-UAE in high resolutions via P96?

Thanks for looking!

[Hewitson]

Why would you bother Toni with a FS-UAE problem?

[britelite]

Originally Posted by Hewitson

Why would you bother Toni with a FS-UAE problem?

In what way is he bothering Toni?

[Weaselrama]

I was informed by Amiga users in the FB group, "The Amiga Computer" that this was a potential bug and that I should contact Toni with the issue as he is an FS-UAE developer. I would apologize to him directly if this is incorrect. I didn't want to file a bug report unless I could confirm this was an actual bug and not just normal FS-UAE behavior.

[FrodeSolheim]

Hewitson is probably correct in that this is most likely an FS-UAE problem, and Toni isn't directly involved with FS-UAE (He works on WinUAE, and his great work on improvements there trickles down to FS-UAE). But let's not make a big deal out of a small misunderstanding

To comment on the actual issue, I'm not certain what's going on here. I do know that the fast-possible-mode isn't working ideal in FS-UAE, and the combination of fastest-possible-mode and UAEGFX may be a a bit buggy. This is something I'm working on for the next development release of FS-UAE actually (I also had to, because after updating FS-UAE to newer code from WinUAE, fastest-possible mode in FS-UAE didn't work well at all).

I don't have a good explanation about why resolution matters here, except higher resolution = more data, and more data is slower, so there's definitively a possibility this might affect timing somehow.

So, it's possible this will be fixed in the upcoming dev release, will be interesting to test

@Weaselrama This is definitively the right place to report this problem, thanks for your detailed report and thorough testing so far.

[Weaselrama]

[QUOTE=FrodeSolheim;@Weaselrama This is definitively the right place to report this problem, thanks for your detailed report and thorough testing so far.[/QUOTE]

Thanks very much for your kind response. I understand now that Toni is not directly involved in FS-UAE. As I tested this I was and am hopeful it was an FS-UAE issue and not a P96/UAEGFX issue in which screen resolution translated into higher load on the Macbook's processor. If that's the case, I accept it but I'd much rather be able to run in 1920 x 1080 without audio latency. While I ran it in the higher res I actually did not note any higher load on the Mac's resources. FS-UAE continued to use, on the average, about 103% of the CPU and continues to do so at the lower 1280 x 1024.

Thanks again for the response here!

[Weaselrama]

Just a note to say I consider this issue resolved under FS-UAE 3.0.2. I still have the uae_cpu_speed = max set, but after installing I was able to run 1920 x 1080 with none of the audio latency reported above. Many thanks to Frode and the FS-UAE dev team!

[malko]

Originally Posted by Weaselrama

[...] Many thanks to Frode and the FS-UAE dev team!

FS-UAE dev team IS Frode (alone)
But yes, like Toni, Frode is doing an amazing job for us to still be able to enjoy the joy of the Amiga on "modern" (hum) platforms

[Weaselrama]

Originally Posted by malko

FS-UAE dev team IS Frode (alone)
But yes, like Toni, Frode is doing an amazing job for us to still be able to enjoy the joy of the Amiga on "modern" (hum) platforms

He certainly is! Thanks for the correction, I was unaware.

However, I need to report that after further testing the audio latency issue has RETURNED. It just takes longer to make its appearance. Pity - I was really enjoying returning to 1920 x 1080 but alas, I'm back in 1280 x 1024 mode.

[FrodeSolheim]

I would be very surprised if it was fixed, there hasn't been any relevant fixes between 3.0.0 and 3.0.2 ;-)

But as I mentioned earlier, there's a good change it will be fixed in the new development series

[Weaselrama]

Originally Posted by FrodeSolheim

I would be very surprised if it was fixed, there hasn't been any relevant fixes between 3.0.0 and 3.0.2 ;-)

But as I mentioned earlier, there's a good change it will be fixed in the new development series

I figured as much. Sometimes we talk ourselves into believing improvements exist where they don't. In my case, I suppose it comes from the passion I have in modding/upgrading this OS 3.9 setup which I've been documenting on the FB "The Amiga Computer" page.

I'd like to make an observation about what I experienced and preface it by asking this: Would or could the IP stack handling Internet traffic have anything to do with load - possibly on the Mac side which could affect how well FS-UAE processes data? Here's why I ask:

It was very early morning when, after upgrading FS-UAE that I decided to run and test 1920 x 1080. I was running iBrowse 2.5.1 and playing 320 kbps mp3s in AMPlifier. There was no latency. I will note here that iBrowse was *flying* insofar as how fast pages were loading and I convinced myself that there had been significant improvement in how fast my Bench was running.

During those hours, Internet usage via my provider is extremely light. 04:30 isn't a peak usage time by any means.

When I finally went to bed (yes, I have Insomnia) and woke up several hours later, I fired up FS-UAE and almost immediately realized the problem persisted just as badly as ever causing me to switch back to 1280 x 1024. As iBrowse was grinding on, trying to open EAB, the visual effects in AMPlifier nearly froze and the audio ran very slow as if the speed had been turned down.

So: Can Internet speed equate to higher load and therefore poorer performance?

I have to reiterate I'm very pleased with this configuration running a 68060 (w/ uae_cpu_speed = max. Without this option, I simply don't get the performance) running at this resolution but even switching to 1344 x 1080 the audio latency is terrible. I'm including this information just in case it's important. It is palpably faster than running a 68040, regardless of the comments I've read here on EAB that suggest there's no reason to run a 68060. The performance is consistently better than the 68040. I will also note - and by now you realize I do a LOT of due-diligence in confirming my observations - that running the Fastest Possible switch mentioned above on the 68040 *degrades* its performance. It vastly improves the performance on the 68060.

My apologies if I ran slightly off-topic but I wanted to be as thorough as possible.

Thanks again, Frode, and I look forward to testing any new Dev versions you might publish.