Exercise audio continuity during video stalls and generation changes

tools/chatgui/tests/test_stream_view.cpp

@@ -24,6 +24,7 @@
 #include <cmath>
 #include <chrono>
 #include <deque>
+#include <thread>
 
 extern "C" {
 #include "utun_instance.h"
@@ -82,6 +83,7 @@ static QImage nativeCrop(const QImage& frame, const VideoRenderWidget& view, QPo
 }
 #if defined(TEST_NULL_AUDIO) && defined(HAVE_FFMPEG)
 static std::atomic<bool> delayedDecoder{false};
+static std::atomic<unsigned> videoPauseMs{0}, videoPauses{0};
 static AVCodecContext* delayedContext = nullptr;
 static std::deque<AVFrame*> delayedFrames;
 static bool delayedDraining = false;
@@ -96,6 +98,11 @@ extern "C" int __wrap_avcodec_open2(AVCodecContext* context, const AVCodec* code
 }
 extern "C" int __real_avcodec_receive_frame(AVCodecContext*, AVFrame*);
 extern "C" int __wrap_avcodec_receive_frame(AVCodecContext* context, AVFrame* frame) {
+    if (unsigned pause = videoPauseMs.exchange(0)) {
+        ++videoPauses;
+        DEBUG_INFO(DEBUG_CATEGORY_STREAM, "fixture video decoder stall=%ums; audio worker must continue", pause);
+        std::this_thread::sleep_for(std::chrono::milliseconds(pause));
+    }
     if (context != delayedContext) return __real_avcodec_receive_frame(context, frame);
     int result = __real_avcodec_receive_frame(context, frame);
     if (!result) {
@@ -687,6 +694,14 @@ private slots:
         QVERIFY2(shown.count() >= beforeSteady + 30, "30fps video must keep advancing with 200ms physical audio latency");
 #ifdef TEST_NULL_AUDIO
         QCOMPARE(silenceGaps.load(), gapsBefore);
+        uint64_t beforePause = nonzeroSamples.load(); unsigned pausesBefore = videoPauses.load();
+        videoPauseMs = 500;
+        QTest::qWait(650);
+        QCOMPARE(videoPauses.load(), pausesBefore + 1);
+        QCOMPARE(silenceGaps.load(), gapsBefore);
+        QVERIFY(nonzeroSamples.load() > beforePause + 40000);
+        DEBUG_INFO(DEBUG_CATEGORY_STREAM, "[PASS] video stalled 500ms: audio continued samples=%llu new_gaps=0",
+            (unsigned long long)(nonzeroSamples.load() - beforePause));
 #endif
         {
             StreamPlayerWindow second(group, inst->node_id, epoch, "Second reader"); second.show();