Long scene uptime causes pause on StartCapture

[echarles-dev]

I'm debugging an issue which presents as follows (from a legacy project):

•  A Capture From Camera component is present in a scene. 
• When StartCapture is called on that component, there is a pause before recording starts, which seems to hang the whole thread - live video is blocked, and no interactions are recognized. 
• The length of the pause seems to be proportional to how long the Capture From Camera component exists in the scene, or the time since the last capture ended - that is to say, I can switch to another scene and back, and the pause duration seems to reset, or I can start and stop a capture and that will reset the pause duration as well.

System Setup

• Unity version: 2018.1.5f1
• AVPro Movie Capture version: 3.6.7
• Operating system version: Windows 10 Home
• Capture component used: Capture From Camera
• Capture settings (resolution, frame-rate, codec): 1920x1080, 30fps, uncompressed
• Full capture settings attached as screen caps

To Reproduce I have a minimal project that I can provide if it's helpful. In the project, the STR are as follows:

1. Open the application
2. Wait ~2 minutes
3. Initiate capture
4. Observe long pause

Other Notes/Things I've Tried

• Unity's profiler pointed me to CaptureBase.LateUpdate()>Camera.Render>Gfx.WaitForPresent. I think this is misleading, because that's Unity's own thread that's being blocked - I'm just not sure by what, and deep profiling didn't produce any different results.
• Running on a different PC shows the same behavior (worse actually - possibly due to a worse graphics card?)
• Setting the game object that holds the Capture From Camera component to active/inactive has no effect on the pause - it really seems to be tied to the object's existence, not its activity state.
• The pause seems to be more significant in the compiled version of the app versus the editor. Toggling CaptureAudio, Allow V Sync Disable, and Force Gpu Flush all seem to have no effect.

Thanks for any insight!

[AndrewRH]

Thanks for this report - how long a pause are we talking about here?

[echarles-dev]

If I let the program run for 5 minutes or so, I see a pause of 4-5 seconds. If I run it for less than a minute, the pause is less than a second (totally fine and expected).

On Tue, Aug 25, 2020 at 6:00 PM Andrew notifications@github.com wrote:

Thanks for this report - how long a pause are we talking about here?

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[echarles-dev]

I have an update on this. The problem seems to be caused by the very specific case where a CaptureFromCamera component uses a Camera in the scene as input whose Target Display does not exist in the real world. In my case, I have three displays (2 physical, 1 virtual), and the source camera was targeting Display 4.

I'll also note that the problem camera is pointed at the output of an AVProLiveCamera component, but I didn't do enough testing to determine if that's a factor or not.

I don't think I know now whether this is actually a bug in the CaptureFromCamera component or something else - maybe Unity itself, my graphics card, or an interaction between the live camera and the recording component - or maybe this is working as designed, and you should just not point a camera at a nonexistent display. Happy to close this thread if you don't think it warrants further investigation.

[AndrewRH]

Ohhhhh interesting! well thanks for the feedback - that's really appreciated! Okay I will just try a few things and then if I can't find anything I will close this thread.

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This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

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