fix(windows): end the audio track where the video ends

electron/native/wgc-capture/src/audio_sample_utils_test.cpp

@@ -1572,6 +1572,26 @@ int main() {
             expect("mixer-resume-continues-at-the-pause", first != left.end() && std::abs(at - pausedAtMs) <= 40.0, detail);
         }
 
+        // (5) A pause followed by a stop, as the helper ends every take (#942):
+        // the track ends at the pause, not at the stop that comes later.
+        {
+            const auto packet = dcPacket(0.5f);
+            double pausedAtMs = 0.0;
+            const auto left = runTake(false, true, [&](AudioMixer& mixer, Clock::time_point t0) {
+                capture(
+                    [&] { mixer.pushMicrophone(packet.data(), static_cast<DWORD>(packet.size())); },
+                    t0, 40, 1000, 0);
+                pausedAtMs = std::chrono::duration<double, std::milli>(Clock::now() - t0).count();
+                mixer.setPaused(true);
+                std::this_thread::sleep_for(milliseconds(300));
+            });
+            const double lengthMs = msAt(left.size());
+            char detail[96]{};
+            sprintf_s(detail, "track %.1f ms long, paused at %.1f ms", lengthMs, pausedAtMs);
+            std::cout << "JITTER_RAW stop-after-pause " << detail << std::endl;
+            expect("mixer-track-ends-at-the-pause-before-a-stop", std::abs(lengthMs - pausedAtMs) <= 20.0, detail);
+        }
+
         // (4) The same with a resume that follows the pause at once, before the
         // mixer has had a chance to see the pause: the resume must wait for the
         // cushion to be written, or it throws the cushion away and what follows

electron/native/wgc-capture/src/main.cpp

@@ -1549,6 +1549,17 @@ int wmain(int argc, wchar_t* argv[]) {
 
     control.waitForStop();
 
+    // The take ends here, for the sound as for the picture: the video writer
+    // stops on this same request. The mixer is clock-driven, so left running
+    // it would go on writing chunks through the half second the steps below
+    // take, and every take ended with ~0.5 s of audio past its video
+    // (getopenscreen/openscreen#942, measured on three takes). A pause writes
+    // what the cushion holds up to this instant and then nothing; one already
+    // in place is left where it is.
+    if (audioMixer) {
+        audioMixer->setPaused(true);
+    }
+
     const auto stopStart = std::chrono::steady_clock::now();
     auto stopElapsedMs = [&] {
         return std::chrono::duration_cast<std::chrono::milliseconds>(