- Wed May 29, 2019 12:34 am
I've tried Lars' suggestions about audio a while ago thinking that it was a video / codec problem before.
These have been my steps to diagnosis so far, documented here.
Far as I can see, if you use anything that relies on native codecs, your video / audio will be out of sync. For example, VLC will be out of sync, and it'll be cutting every few seconds because it resets itself noticing that it got out of sync. That to most people looks like an audio issue (vlc cutting) but it doesn't seem to be — it's your whole system going 5% faster based on the CPU clock. You can see the cuts happening on VLC debug logs, it says it got too far out of sync and cuts it.
So far, these are the things that you can have trouble with:
- Safari, on YouTube (which uses the native codec)
These are the things that won't have that problem:
- IINA player (This works, I'm using this)
- MPV player (? not sure)
- Firefox or Chrome using their own codecs
It's also not a 'video feed falling behind' issue — I have a Radeon Vega 64, it's capable of driving 2x 8k displays (or something like that), it likely won't have trouble driving my 4k display. I suspect that video is running at the normal speed, governed by the GPU's own clock, while audio is using CPU's ~5% faster clock, which gets out of sync pretty fast.
These are the things I tried:
- All audio fixes I could find (before realising it's not an audio issue)
- Setting busratio to 37, 36, as boot flag, from the CPU tab in Clover (boot flag had no effect, setting it from the CPU tab caused the value read from the About pane to change, but otherwise no effect?)
- Setting FSB explicitly to 100,000, slightly higher, slightly lower values, no effect
- I had no overclock in place, but I went to my bios and tried to disable anything that I can find - it's basically flat 3.7ghz excluding core boost, (AMDs equivalent of turbo boost)
Things that I haven't tried yet:
- Disabling core boost, so that the processor runs at a fixed 37 busratio. My hypothesis for this one is that I noticed on the boot logs the turbo boost / up rate is shown as 0, so the OS sees the processor as incapable of turbo boosting. If the processor *still* turbo boosts on its own, that might be the reason the skew happens. That would also explain why busratio doesn't work.
I'll try this when I go home. If in the small chance this actually helps, I'll report back. However, even in the case this works, shutting off core boost is probably loses you some performance.
In short — we probably need some patches specific to 2700x, it seems. I'm a software guy, I would go at it myself but I don't really know where to start. If anyone has any ideas, happy to take a look.