Video stream pauses when under 30ish FPS | ALVR | Page 1

minor venture Jun 9, 2025, 2:22 PM

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Whenever a game goes under 30fps I don't get any new frames inside the headset, but the streamer says it's still streaming like normally. Opening the steamvr dashboard makes it so I can see new frames again as it's then running at 90fps. This both happens when streaming wired and wireless to a quest 2, I almost always use wired tho.

PC Specs:
CPU: 14700k
GPU: RX 7900xt
RAM: 32gb @ 6200MT/s

📎 StF3VEX.json

minor venture Jun 9, 2025, 10:06 PM

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yea it doesn't seem to be an issue on my laptop that has nvidia graphics, although last time i checked was 9 months ago

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and i often get under 30fps in vrc because of cpu limitations, and when opening the steamvr dashboard i can see vrc is running sub 30fps but the dashboard renders at 90fps as the frame time graph shows

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and to add to the no new frames being shown, it seems like the client freezes

minor venture Jun 15, 2025, 8:05 PM

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I found something pretty interesting, looking at the Video Codec Engine of my gpu it goes to 0% when it falls under 30fps, and the stream graphs stop

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This is with a fresh session.json

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this both happens with h264 and HEVC encoding

minor venture Jun 15, 2025, 8:28 PM

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also tried software encoding and it gives me the same issue when going under 30fps

minor venture Jun 15, 2025, 9:13 PM

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I have tried steamlink now too, and it doesn't behave the same. it still encodes and shows frames even under 30fps

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I'll try to make a video showing what happens in the couple of days, if that's any help to you all

minor venture Jun 30, 2025, 8:52 PM

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Here's a video of the issue, I'm using amd chill mode to manually limit the fps as it gives the same result.

Some extra notes:

Task manager shows encoder usage, this normally goes to 0 when the stream pauses, but I'm using it to also record my screen so instead it just goes to a slightly lower usage amount.
Top game window is Half Life Alyx on my pc, as you can see the rendering and tracking continues. Although stutter because of low fps, which is expected.
Bottom game window is the view from the headset captured through scrcpy.
Audio continues to stream to the headset, only video doesn't.

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and here's the lastest version of my session.json

📎 session.json

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And to add it seems to not always be 30fps, but can sometimes be closer to about 40fps. Although I did not record this.

minor venture Jul 6, 2025, 12:38 PM

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@grand delta any idea why this could happen? I tried all releases back to v20.8.1, and all have the same exact issue. It also happens on my laptop that has an nvidia gpu (rtx 3050).

From what I've seen it seems to be an issue fully on the host side, maybe with the encoding or compositor. Although I don't know enough about how alvr works.

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Video stream pauses when under 30ish FPS

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well I'm not sure if it's windows only, I only tried it on windows. but if it's an issue with the host it could also be on linux

#Video stream pauses when under 30ish FPS