Add a switch to print video latency.

[nageru] / print_latency.cpp

diff --git a/print_latency.cpp b/print_latency.cpp
new file mode 100644 (file)
index 0000000..0b0a1ae
--- /dev/null
+++ b/print_latency.cpp
@@ -0,0 +1,30 @@
+#include "print_latency.h"
+#include "flags.h"
+
+#include <stdio.h>
+#include <chrono>
+#include <string>
+
+using namespace std;
+using namespace std::chrono;
+
+void print_latency(const string &header, const ReceivedTimestamps &received_ts, bool is_b_frame, int *frameno)
+{
+       if (received_ts.max_ts == steady_clock::time_point::min())
+               return;
+
+       // 101 is chosen so that it's prime, which is unlikely to get the same frame type every time.
+       if (global_flags.print_video_latency && (++*frameno % 101) == 0) {
+               const steady_clock::time_point now = steady_clock::now();
+               printf("%-60s %4.0f ms (lowest-latency input), %4.0f ms (highest-latency input)",
+                       header.c_str(),
+                       1e3 * std::chrono::duration<double>(now - received_ts.max_ts).count(),
+                       1e3 * std::chrono::duration<double>(now - received_ts.min_ts).count());
+
+               if (is_b_frame) {
+                       printf("  [on B-frame; potential extra latency]\n");
+               } else {
+                       printf("\n");
+               }
+       }
+}