Frame dropping/skipping happens for captured videos in preview window and recorded files

pbjacob86

New Member
First of all, I use OBS only for recording some teaching lesson videos, not for live streaming, not for game recording.

PC hardware:
i7-11700K, NVIDIA 1650 4G(DDR6), 32G 2666 RAM, 980pro SSD in PCIE 4.0 slot

Operating System:
Win 10 1809 LTSC
Win 10 21H2 Enterprise

OBS version:
27.2.4(the latest version till now)

Output Settings:
NVIDIA NVENC new, CQP 20 (GPU 3D and encoder usage lower than 40%)
X264, CRF 23, very fast (CPU usage lower than 30%)
Apple ProRes via FFmpeg (proxy, LT, std, HQ have the same results)

Video Settings:
1920 x 1080 (25/29.97/30/59.94/60, all downscale filters have the same results)

Main issue:
When capturing the camera video by a capture card, ‘frame skipping’ or ‘frame dropping” can be seen.

Detailed description:
This not only happens in recording, but also in preview window even not recording. This happens not very regularly, 1 or 2 skips after 5-10 seconds. Sometimes, FPS may be under 20 for a while.

This frame skipping problem can be easily seen directly from eyes, and can be also verified by the recorded video file. When frame skipping happens, the real frame is discarded, and the last frame is copied to fill the dropped frame. So you can see the desired smoothly moving object in the video suddenly jumps sometimes.

However, OBS Stats window doesn’t count these missed frames at all, that is, FPS is not changed and no missed frames are calculated when frame skipping truly happens.

I have test 3 video capture cards: an AVerMedia GC551 card, an unknown brand USB 3.0 card, and a PCI-E card. They all have the same results.

However again, when I use potplayer to open the captured videos, no frame skipping happens. When I use RECentral (AVerMedia software) to open video from AVerMedia GC551, no frame skipping happens. It seems that OBS doesn’t handle the captured video signals quite well.

I have done a lot of searching for this. OBS in admin: yes; Process Priority: high; system high performance for OBS: yes; Game mode: on/off seems the same; Latest GPU driver: yes; Latest OS system: yes; Latest OBS: yes; Buffering: auto/on/off seems the same… you name it, I have tried almost every possible way to fix this issue, even under 3 different computers, but the dropping still happens in OBS.

Is there anyone suffering the same problem like me? How can we fix it?

Maybe the last method for me is to buy an OBS certified AUSU CU4K30 card, and I may face the final result that dropping fames are inevitable in OBS if CU4K30 acts the same. Is there anyone using AUSU CU4K30?

Thank you so much.
 

pbjacob86

New Member
Here is the log. Some frames are truly dropped when recording according to the log file.
 

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