Fix/windows desktop capture

webrtc-jni/src/main/cpp/dependencies/webrtc/CMakeLists.txt

@@ -228,7 +228,15 @@ elseif(LINUX)
     target_compile_definitions(${PROJECT_NAME} PUBLIC WEBRTC_LINUX WEBRTC_POSIX WEBRTC_USE_H264 WEBRTC_USE_X11 WEBRTC_USE_PIPEWIRE WEBRTC_USE_GIO)
     target_link_libraries(${PROJECT_NAME} X11 Xext Xfixes Xdamage Xtst Xrandr Xcomposite dbus-1 ${GIO_LIBRARIES} ${GBM_LIBRARIES} ${DRM_LIBRARIES})
 elseif(WIN32)
-    target_compile_definitions(${PROJECT_NAME} PUBLIC WEBRTC_WIN WEBRTC_USE_H264 NOMINMAX WIN32_LEAN_AND_MEAN NDEBUG)
+    # RTC_ENABLE_WIN_WGC must match the gn build: webrtc.lib is compiled with gn's
+    # default rtc_enable_win_wgc=true (webrtc.gni: "rtc_enable_win_wgc = is_win"),
+    # and DesktopCaptureOptions has members guarded by that define. Compiling the
+    # JNI wrapper without it changes the class layout and size (64 vs 80 bytes as
+    # of branch-heads/7977) — the out-of-line CreateDefault()/copy constructor in
+    # the lib then overflow the wrapper's smaller stack slot and every member
+    # after the guarded block is read at wrong offsets, silently breaking desktop
+    # capture (same ABI bug WEBRTC_USE_X11 fixed on Linux).
+    target_compile_definitions(${PROJECT_NAME} PUBLIC WEBRTC_WIN WEBRTC_USE_H264 NOMINMAX WIN32_LEAN_AND_MEAN NDEBUG RTC_ENABLE_WIN_WGC)
     target_link_libraries(${PROJECT_NAME} D3D11 DXGI user32 gdi32 iphlpapi dmoguids msdmo secur32 strmiids winmm wmcodecdspuuid ws2_32)
 endif()
 

webrtc-jni/src/main/cpp/src/media/video/VideoTrackDesktopSource.cpp

@@ -194,7 +194,13 @@ namespace jni
 			buffer->MutableDataU(), buffer->StrideU(),
 			buffer->MutableDataV(), buffer->StrideV(),
 			crop_x, crop_y,
-			frame->stride() / webrtc::DesktopFrame::kBytesPerPixel, buffer->height(), crop_w, crop_h,
+			// (src_width, src_height) must describe the FULL source frame, not the cropped
+			// output. Passing buffer->height() (== crop_h) here made libyuv's internal
+			// bounds check (crop_y + crop_height <= src_height) fail with -1 whenever
+			// crop_y > 0 — i.e. for every maximized window, whose frame sits at
+			// top_left().y() == -border. Screen frames never hit this branch (exact stride,
+			// fullscreen == true), which is why only window capture appeared broken.
+			frame->stride() / webrtc::DesktopFrame::kBytesPerPixel, height, crop_w, crop_h,
 			libyuv::kRotate0,
 			libyuv::FOURCC_ARGB);
 

webrtc-jni/src/main/cpp/src/media/video/desktop/DesktopCaptureCallback.cpp

@@ -44,6 +44,11 @@ namespace jni
 		JNIEnv * env = AttachCurrentThread();
 
 		if (result != webrtc::DesktopCapturer::Result::SUCCESS) {
+			// Propagate the failure to Java instead of silently dropping it —
+			// callers waiting for a frame otherwise have to rely on timeouts.
+			auto jerror = JavaEnums::toJava(env, result);
+			env->CallVoidMethod(callback, javaClass->onCaptureResult, jerror.get(), nullptr);
+			ExceptionCheck(env);
 			return;
 		}
 
@@ -83,7 +88,13 @@ namespace jni
 			i420Buffer->MutableDataU(), i420Buffer->StrideU(),
 			i420Buffer->MutableDataV(), i420Buffer->StrideV(),
 			crop_x, crop_y,
-			frame->stride() / webrtc::DesktopFrame::kBytesPerPixel, i420Buffer->height(), crop_w, crop_h,
+			// (src_width, src_height) must describe the FULL source frame, not the cropped
+			// output. Passing i420Buffer->height() (== crop_h) here made libyuv's internal
+			// bounds check (crop_y + crop_height <= src_height) fail with -1 whenever
+			// crop_y > 0 — i.e. for every maximized window, whose frame sits at
+			// top_left().y() == -border. Screen frames never hit this branch (exact stride,
+			// fullscreen == true), which is why only window capture appeared broken.
+			frame->stride() / webrtc::DesktopFrame::kBytesPerPixel, height, crop_w, crop_h,
 			libyuv::kRotate0,
 			libyuv::FOURCC_ARGB);