Preserve desktop camera cadence under timestamp jitter

tools/chatgui/tests/test_call_video_encoder.cpp

@@ -5,6 +5,7 @@
 #include <clocale>
 #include "../src/call_video_encoder.h"
 #include "../src/call_video_decoder.h"
+#include "../src/call_video_cadence.h"
 #include "../../../src/call/call_video_bitstream.h"
 extern "C" {
 #include "debug_config.h"
@@ -41,6 +42,15 @@ class CallVideoEncoderTest : public QObject {
         return {17, 640, 360, 30, 0, (uint8_t)codec, (uint8_t)(codec == 1 ? 31 : 93), 4000000, (uint8_t)(codec == 1 ? 2 : 1)};
     }
 private slots:
+    void captureCadence() {
+        CallVideoCadence jittered, fast;
+        for (int i = 0; i < 300; i++) QVERIFY(jittered.accept(1000000 + i * 33333 + (i % 2 ? -1500 : 1500)));
+        int accepted = 0;
+        for (int i = 0; i < 600; i++) if (fast.accept(1000000 + i * 1000000LL / 60)) accepted++;
+        QCOMPARE(accepted, 300);
+        QVERIFY(jittered.accept(30000000)); // Долгая пауза не создаёт догоняющий burst.
+        QVERIFY(!jittered.accept(30001000));
+    }
     void initTestCase() {
         debug_config_init(); debug_set_level(DEBUG_LEVEL_WARN); debug_set_category_level(DEBUG_CATEGORY_CALL, DEBUG_LEVEL_DEBUG);
         av_log_set_level(AV_LOG_ERROR);