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Post by nathanzachary on Apr 5, 2023 10:25:15 GMT -5
Hello,
I have a rather strange issue with HDMI on my XMC-1, but I'm going to try to explain it as thoroughly as I can in hopes that someone can give me some pointers. I have a mini-PC that I built running Gentoo Linux with MPD for bit-perfect audio connected via USB to my XMC-1. Everything on that front is perfect. I also have the same mini-PC connected via HDMI so that I can play my retro video games via an emulator (Mednafen, in this case). It works very well in most cases. However, there are certain games where the audio via HDMI stutters terribly. If I bypass the XMC-1 completely, and just connect the mini-PC HDMI output to the TV HDMI input and listen only through the sub-par TV speakers, the stuttering stops. So, I believe that there is some type of processing happening in the XMC-1 that causes the audio stuttering on these particular games.
I have found other threads online with people seeing the same problem from certain sound bars and other processors/AVRs. Some examples are:
Is there anything that I can do to try to eliminate the problem here via the XMC-1? For instance, on these certain games exhibiting the problem, is there a way that I can temporarily disable audio processing of the XMC-1?
Any other suggestions?
I greatly appreciate your time and help.
Cheers, Nathan Zachary
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Post by 405x5 on Apr 5, 2023 10:45:58 GMT -5
Hello,
I have a rather strange issue with HDMI on my XMC-1, but I'm going to try to explain it as thoroughly as I can in hopes that someone can give me some pointers. I have a mini-PC that I built running Gentoo Linux with MPD for bit-perfect audio connected via USB to my XMC-1. Everything on that front is perfect. I also have the same mini-PC connected via HDMI so that I can play my retro video games via an emulator (Mednafen, in this case). It works very well in most cases. However, there are certain games where the audio via HDMI stutters terribly. If I bypass the XMC-1 completely, and just connect the mini-PC HDMI output to the TV HDMI input and listen only through the sub-par TV speakers, the stuttering stops. So, I believe that there is some type of processing happening in the XMC-1 that causes the audio stuttering on these particular games.
I have found other threads online with people seeing the same problem from certain sound bars and other processors/AVRs. Some examples are:
Is there anything that I can do to try to eliminate the problem here via the XMC-1? For instance, on these certain games exhibiting the problem, is there a way that I can temporarily disable audio processing of the XMC-1?
Any other suggestions?
I greatly appreciate your time and help.
Cheers, Nathan Zachary
I would start with the fundamentals on the XMC….Do you have the latest firmware installed for whichever HDMI board is installed in your unit……and coupled with that the latest HIGH speed HDMI cable. |
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Post by nathanzachary on Apr 5, 2023 10:53:17 GMT -5
Thank you for your reply. I have an original XMC-1, and the firmware details are:
HDMI: 1.2
I don't think that I can use any firmware later than the one that I have.
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Post by ttocs on Apr 5, 2023 11:34:23 GMT -5
I have an original XMC-1, and the firmware details are: So, you've also got the original HDMI board, not the V3 board, correct? If so, then the stuttering might be due to processing of the audio signal, like you say. Have you tried various Sound Modes? How about using optical into the XMC-1 just to squelch any idea that it's HDMI related? I listened to the audio you linked to, but I'm not familiar with how it's supposed to sound so I only heard a little of what might be skipping. |
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Post by nathanzachary on Apr 5, 2023 13:03:14 GMT -5
Yes, I have the original board since I never sent it back for any upgrades (or performed them myself). I have tried the various sound modes (e.g. Direct, Reference Stereo), but they haven't made a difference. I also tried forcing HDMI for video but USB for audio (since my MPD music server is functioning as I expect), but the stuttering was still there. One other thing that I thought might work (but didn't), was to put the XMC-1 in standby mode and just pass through the HDMI video. Then I thought it might be possible to just play the audio through the TV, but alas, there was no audio at all that way. 
The only workaround I have found so far is to connect from the mini-PC's HDMI output directly to the TV's HDMI input whenever I want to play these particular games. It's not ideal because of swapping the cables, and more importantly, losing the ability to hear the sound through my 5.1 setup, but at least I will have my sanity.  |
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KeithL
Administrator 
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Post by KeithL on Apr 5, 2023 13:42:13 GMT -5
There's a lot going on when you send audio over HDMI. The HDMI connection must negotiate a video frame rate and resolution that everyone supports... And, with a game, which essentially generates the audio and video separately, the audio portion of the signal then has to be MUXed with the video... It's possible that, once the HDMI negotiation is successful, the emulator cannot work out how to match the audio to the negotiated video parameters. Or it's possible that the game "insists" on delivering the audio at a rate that synchs with its video output frame rate.... And it may favor one specific frame rate... And many AVRs and processors, including the XMC-1, only accept video at "standard A/V frame rates", and won't accept some of the weird frame rates and resolutions offered by computers. This may be forcing the emulator to be using some standard parameters rather than the ones that the game and the emulator would prefer. And, if so, then it may be forcing the emulator to try to generate MUXed HDMI video and audio using parameters that the game isn't happy with. (The game may be "trying to run at" some odd frame rate that your TV will accept but a standard AVR or pre/pro will not... and glitching when it doesn't match.) Do the games you're using actually support 5.1 channels... or do you care? What I'm wondering is if you can set the emulator to use USB audio rather than HDMI. If you can, it will make life a lot simpler for the emulator, since it will no longer have to MUX the audio and video. If that works, you could sent the audio into the USB audio input on the XMC-1, and configure that as the audio source for that video input. You could then play that audio in stereo... or simulated surround via PLIIx... It's just a guess but it's worth a try... Hello, I have a rather strange issue with HDMI on my XMC-1, but I'm going to try to explain it as thoroughly as I can in hopes that someone can give me some pointers. I have a mini-PC that I built running Gentoo Linux with MPD for bit-perfect audio connected via USB to my XMC-1. Everything on that front is perfect. I also have the same mini-PC connected via HDMI so that I can play my retro video games via an emulator (Mednafen, in this case). It works very well in most cases. However, there are certain games where the audio via HDMI stutters terribly. If I bypass the XMC-1 completely, and just connect the mini-PC HDMI output to the TV HDMI input and listen only through the sub-par TV speakers, the stuttering stops. So, I believe that there is some type of processing happening in the XMC-1 that causes the audio stuttering on these particular games. I have found other threads online with people seeing the same problem from certain sound bars and other processors/AVRs. Some examples are: Is there anything that I can do to try to eliminate the problem here via the XMC-1? For instance, on these certain games exhibiting the problem, is there a way that I can temporarily disable audio processing of the XMC-1?
Any other suggestions? I greatly appreciate your time and help. Cheers, Nathan Zachary
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Post by nathanzachary on Apr 5, 2023 15:07:21 GMT -5
Hi Keith,
Thank you for the detailed explanation. I actually already tried setting the emulator (well, the whole OS) to use USB for audio even though it was using HDMI for video output. Unfortunately, that resulted in the same audio stuttering. The strangest part to me is that many games work just fine. Only a handful that I have tried exhibit this audio stuttering problem. I'm not sure what is different with them, but other people with different equipment have seen the same problem unless directly connecting to the TV.
I'll keep experimenting, but I may just have to deal with connecting it directly to the TV when I want to play these particular games.
Thanks again for the information!
Cheers,
Nathan Zachary
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Post by nathanzachary on Apr 5, 2023 16:16:24 GMT -5
One interesting thing that I found by experimenting is that if I change the emulator's sample rate from 48KHz to 192KHz, the stuttering isn't quite as awful. It's still bad, but it misses about every other note instead of 6-7 out of 10. I would just like to know what makes the audio on most games perfectly fine whereas some are botched.
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Post by ttocs on Apr 5, 2023 16:28:14 GMT -5
One interesting thing that I found by experimenting is that if I change the emulator's sample rate from 48KHz to 192KHz, the stuttering isn't quite as awful. It's still bad, but it misses about every other note instead of 6-7 out of 10. I would just like to know what makes the audio on most games perfectly fine whereas some are botched. This is interesting. Have you tried super low sample rate, if there are any to choose from? Those old games were single digit quality after all. |
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KeithL
Administrator
Posts: 9,958
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Post by KeithL on Apr 5, 2023 16:34:01 GMT -5
Unfortunately, depending on how old the games are, they may literally have been coded to work at specific resolutions, frame rates, and audio sample rates. As such it means that the emulator has to do a lot to "trick them" into "thinking" they're running on their intended hardware... While, at the same time, converting both their audio and video outputs to work on different hardware... Hi Keith, Thank you for the detailed explanation. I actually already tried setting the emulator (well, the whole OS) to use USB for audio even though it was using HDMI for video output. Unfortunately, that resulted in the same audio stuttering. The strangest part to me is that many games work just fine. Only a handful that I have tried exhibit this audio stuttering problem. I'm not sure what is different with them, but other people with different equipment have seen the same problem unless directly connecting to the TV. I'll keep experimenting, but I may just have to deal with connecting it directly to the TV when I want to play these particular games. Thanks again for the information! Cheers, Nathan Zachary |
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