Use minimal timer access and diagnose failed video image transforms

tools/chatgui/src/call_video_decoder.cpp

@@ -188,7 +188,10 @@ int CallVideoDecoder::receive(call_video_frame& f, QImage& image) {
             uint8_t* planes[4] = {output.bits(), nullptr, nullptr, nullptr}; int strides[4] = {(int)output.bytesPerLine(), 0, 0, 0};
             if (sws_scale(m->scale, pixels->data, pixels->linesize, 0, pixels->height, planes, strides) != pixels->height)
                 result = AVERROR_INVALIDDATA;
-            else image = f.format.rotation ? output.transformed(QTransform().rotate(f.format.rotation)) : output;
+            else {
+                image = f.format.rotation ? output.transformed(QTransform().rotate(f.format.rotation)) : output;
+                if (image.isNull()) result = AVERROR(ENOMEM);
+            }
         }
     }
     av_frame_free(&copied); av_frame_free(&decoded);

tools/chatgui/src/call_video_wake.h

@@ -27,7 +27,8 @@ public:
     CallVideoWake() {
 #ifdef _WIN32
         event = CreateEventW(nullptr, FALSE, FALSE, nullptr);
-        timer = CreateWaitableTimerExW(nullptr, nullptr, 0x00000002, TIMER_ALL_ACCESS);
+        constexpr DWORD highResolution = 0x00000002; // CREATE_WAITABLE_TIMER_HIGH_RESOLUTION (Windows 10 1803+).
+        timer = CreateWaitableTimerExW(nullptr, nullptr, highResolution, TIMER_MODIFY_STATE | SYNCHRONIZE);
         if (!timer) {
             DEBUG_WARN(DEBUG_CATEGORY_CALL, "video high resolution timer unavailable error=%lu; using regular timer", GetLastError());
             timer = CreateWaitableTimerW(nullptr, FALSE, nullptr);