How could I Control frame rate? about windows.ui.composition-win32-samples HOT 2 CLOSED

Sorry for taking so long to get to this! Thank you, @MartinClementson, for answering! I appreciate it when the community helps us out. 🙂

When OnFrameArrived is called, there is already a frame waiting for you in the frame pool. You should retrieve it by calling TryGetNextFrame, and then hold onto the Direct3D11CaptureFrame object. As long as you're holding onto a reference, that frame will not be available to the DWM to draw to. Technically, if you sleep before TryGetNextFrame, that frame still isn't available to the DWM but you are also waiting to process the frame until after the sleep. That may not be what you want given your scenario.

You may want to approach this a different way. If you have a frame rate you're shooting for, I'd create a new thread using DispatcherQueueController.CreateOnDedicatedThread and then create a timer on that thread using CreateTimer. When the timer ticks, I would then release the last frame object I was holding onto and wait for the next frame (depending on how close you are to the vblank, this will introduce a bit of latency). Depending on how you engineer your "wait", you may need to create your frame pool using CreateFreeThreaded.

This model isn't too dissimilar to how I put together the Simple Screen Recorder app. The big difference is that instead of a timer, my requests were driven by the encoder I was using. Take a look at the CaptureFrameWait object. That project is in C#, but the same approach should work in C++.

As far as the crash you're seeing, I'm unable to reproduce it. If you're able to share a memory dump at the moment you hit the crash, I can take a look to see why it happens.

from windows.ui.composition-win32-samples.

Hi.

I asked a similar question to robmihk some time back. His reply might help you.

from Robmikh, Re:Controling frame rate:

The DWM will render a new frame if a buffer is available. This means you can control the rendering by controlling the lifetimes of the Direct3D11CaptureFrame objects.

For example, if you have a frame pool with 2 buffers, you can stop the DWM from rendering by holding onto two Direct3D11CaptureFrame objects (don't release or dispose/close them). Releasing a frame will make it available to the DWM again.

We've had clients who make their frame pool 1 buffer to make that control easier.

I did some prototyping, but can't find the repo at the moment.
but basically change to one buffer;
m_framePool = winrt::Direct3D11CaptureFramePool::Create(m_device, m_pixelFormat, 1, newSize);

You may want to put your sleep after TryGetNextFrame. I think the sleep will make you lose the chance to get ownership of the frame buffer, and the DWM will start rendering a new frame while your function is sleeping. So the crash is probably because it's being used by the DMW.

try
auto frame = sender.TryGetNextFrame(); //

//Do stuff

Sleep(yourTime)
frame.Close() // <--- This makes it available to render again.

You'd want to calculate how much you need to sleep depending on the framerate you want and how long it took to render the last frame.

from windows.ui.composition-win32-samples.