Audio stutter in some SNES games on surround receiver

[buffyp00h]

Hi Forum.

I have been fighting on and off with this issue for a few years and searched all known areas of the internet for a solution without luck, so now I post here.

My setup:
Pi Model or other hardware: 4 model B - 4GB
Power Supply used: Official USB-C powersupply
RetroPie Version Used: 4.7.1
Built From: Standard image from retropie.co.uk - retropie-buster-4.7.1-rpi4_400
USB Devices connected: Buffalo SNES controller, Corsair USB keyboard
Controller used: Buffalo SNES Controller

Description
This is my second attempt at building a retropie console. First time was two years ago on Pi3, which gave me the exact same problem.
My pi is connected to a NAD T777 surround receiver via HDMI. The receiver outputs sound to my passive 5.1 speakers. Connected to the surround receiver is an Epson Tw6600 projector (1080p)

After installing the image and installing ROMs everything works just fine and I can play games and be happy.
However some SNES games have some nasty audio issues where the sound pops/cracks/stutters constantly. A good example is Super Mario World (NTSC) - standard ROM. It's the exact same experience as this guy shows in his video (which I did not record or post. It's just the exact same symptom):

After reading forums back on the PI3 I thought it was related to performance issues on the PI3, so I waited and bought a Pi4 but the issue is the same. I have tried various different emulators, but snes-9x is what I "prefer" - no difference.
I then tried setting up the PI on a different monitor and using analog sound out. The issue disappeared. Then I reconnected to my home theater setup - but used analog sound - no problems. But when I go back to HDMI sound the problem reappears. (analog sound is not a viable solution for me)

So it's clear it has something to do with the setup of the surround receiver and projector. But I have absolutely no clue what is causing it. The setup works perfectly on all other devices I throw at it (ps3, ps4, nintendo switch, Zappiti 4k and more). So I wouldn't say there is anything wrong with it, just that it somehow causes this issue with Retropie. I have played around with refresh rate and sync settings but without any luck (also the sound does work fine in analog, so it seems unlikely to be the cause).

I also tried Lakka instead which gave the same results.

I am hoping someone out there has an idea what could cause this frustrating issue that has haunted me for years and prevented me from making my ultimate retro gaming home theatre setup. Thank you kindly for your help!

[mitu]

@buffyp00h said in Audio stutter in some SNES games on surround receiver:

However some SNES games have some nasty audio issues where the sound pops/cracks/stutters constantl

So this stuttering happens only on some SNES games - so there are SNES games that don't exhibit this issue ? What about other games/systems - does it happen there also ?

What resolution is your display ? Run tvservice -s from the command line and post the output.

[buffyp00h]

@mitu thanks for helping.

Yes, it depends entirely on the game and I have tried different roms to verify that it seems to be the game itself and not just the specific rom. It seems to be mainly a problem with the games released by Nintendo (although Metroid works fine).
It only seems a problem with snes. I play nes, gba and genesis games without issue and havent really tried other systems.

A few examples of games that have stuttering audio:
Super Mario World
Donkey Kong Country

Games without problems:
Megaman X
Chrono Trigger
Super Metroid

As for the tvservice -s output:
state 0xa [HDMI CUSTOM RGB lim 16:9], 1920x1080 @ 60.00Hz, progressive

I hope this can be useful to you and thanks again!
Cheers.

[mitu]

Can you run one of the problematic SNES games with verbose logging enabled and post the log file on pastebin.com ?

[buffyp00h]

@mitu
I have started Super Mario World, which has audio issues immediately from the nintendo logo to the title screen then closed the game. Log can be found here: https://pastebin.com/5x99cfFg

Please let me know if the link doesn't work.

Thanks again!

[mitu]

The link works fine, but I don't see anything wrong with the log, there's no dropped frames or mis-matched framerate.

[buffyp00h]

As it seems not to be sync related according to the log, I took a step out and simply investigated if super mario world from any device over hdmi causes problems. It appears to do so, I found this thread for the SNES mini and other similar consoles. All have the same problem on soundbar systems (and likely also on surround receivers).

https://www.reddit.com/r/miniSNESmods/comments/73fttm/sound_emulation_of_super_mario_world_missing/

I am playing around with my receiver trying to see if any sort of audio processing is causing this - I tried disabling all but the stereo speakers, but none of it changes anything.

I guess I will keep searching or give up eventually.
I just don't get why these particular games generate hdmi sound that gets wrecked by so many setups, one would think there was a way to fix this at the source - the generation of sound on the pi/other device.

[YFZdude]

@buffyp00h said in Audio stutter in some SNES games on surround receiver:

All have the same problem on soundbar systems (and likely also on surround receivers).

I just don't get why these particular games generate hdmi sound that gets wrecked by so many setups, one would think there was a way to fix this at the source - the generation of sound on the pi/other device.

Just my 0.02 here, the world of modern TVs and home theater/surround sound devices is needlessly complicated for these simple old tasks we are trying to recreate here with simple digital signals (ironically that are emulations of old analog signals).

What I would try to see if it helps:
Many TVs have a "game mode" that is intended to reduce or eliminate "signal processing" to enable a more pure, delay free signal and timings. Many surround sound receivers have something similar, although it is usually called Pure Audio or Direct Sound mode. You might see if your receiver has this option and try it to see if it eliminates audio hitches.

For what it's worth, I have an Onkyo receiver at home and even with modern consoles I have noticed that something in the HDMI convergence where all video inputs are routed to a single HDMI output to the TV will cause a 'gap' in sounds sometimes. (After a dead silence of any kind, the first sound made is either dropped entirely or gets cut so I only hear part of it before normal audio resumes. Sort of like the audio stream has to buffer up before it becomes stable again.)

EDIT: Hit the submit button too soon and wasn't done typing.