Create multi OffScreen ChromiumWebBrowser with different URL, the fps will less than i set.

[dxh-sc]

Hi everybody,

I created multi OffScreen ChromiumWebBrowser with different URL, each ChromiumWebBrowser render the image, then will send the image to another server, but i found the render fps less than i set, any idea that i can keep right fps when rendering?

1. one OffScreen ChromiumWebBrowser, i have right fps.
2. two OffScreen ChromiumWebBrowser, i have right fps.
3. three OffScreen ChromiumWebBrowser, the fps will less fps, probably only half of it(formatInfo.FrameRate * 0.5)
4. four OffScreen ChromiumWebBrowser, the fps will less fps, probably only half of it(formatInfo.FrameRate * 0.5)
5. didn't test more.

This is my key code:

example the formatInfo.FrameRate is 25, formatInfo.Width: 1920, formatInfo.Height: 1080

var settings = new CefSettings
{
    // Off-screen rendering core configuration
    WindowlessRenderingEnabled = true,
    // Disable unnecessary log output (improves performance, reduces IO)
    LogSeverity = LogSeverity.Disable,
    // Ignore certificate errors (decide whether to keep based on actual scenario)
    IgnoreCertificateErrors = true,
    // Disable external message pump (recommended for off-screen rendering)
    ExternalMessagePump = false,
    // Set cache path (avoid rebuilding cache on every startup)
    CachePath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "NDIProvider", "cef_cache"),
    MultiThreadedMessageLoop = true
};

// Apply best performance parameters for off-screen rendering
settings.SetOffScreenRenderingBestPerformanceArgs();

// Initialize CEF
return Cef.Initialize(settings, performDependencyCheck: false, browserProcessHandler: null);

int frameRate = formatInfo.FrameRate;
var browserSettings = new BrowserSettings(true)
{
    WindowlessFrameRate = frameRate,
    BackgroundColor = (uint)Color.Transparent.ToArgb()
};

var requestContextSettings = new RequestContextSettings
{
    CachePath = GetCachePath(),
};

var requestContext = new RequestContext(requestContextSettings);
_browser = new ChromiumWebBrowser(url, browserSettings, requestContext)
{
    Size = new Size(formatInfo.Width, formatInfo.Height),
};

await WaitInitAsync(_browser);
_browser.Paint += BrowserOnPaint;
_browser.LoadError += _browser_LoadError;

[amaitland]

but i found the render fps less than i set, any idea that i can keep right fps when rendering?

It's the maximum, there's no guarantees that it's achievable.

// Apply best performance parameters for off-screen rendering
settings.SetOffScreenRenderingBestPerformanceArgs();

Disables GPU, exists for legacy reasons. I would remove this. Make sure you have an app.manifest so GPU detects correctly for better performance.

• three OffScreen ChromiumWebBrowser, the fps will less fps, probably only half of it(formatInfo.FrameRate * 0.5)
• four OffScreen ChromiumWebBrowser, the fps will less fps, probably only half of it(formatInfo.FrameRate * 0.5)

There is only a single UI thread, and from memory all the memory copies happen on the UI thread, there is also locking to keep things in sync, so you'll hit perf limits fairly quickly.

The offscreen implementation is not high performance implementation, everything frame is copied to a bitmap, you can probably get it to run a bit faster by changing some of the internal behavior of where it copies memory, look at the source for https://github.com/cefsharp/CefSharp/blob/master/CefSharp.OffScreen/DefaultRenderHandler.cs

You'll need to write your own custom implementation