1 files changed, 60 insertions, 1 deletions
diff --git a/osdep/timer-win2.c b/osdep/timer-win2.c
index 63c423560f..72bcca5b4e 100644
--- a/osdep/timer-win2.c
+++ b/osdep/timer-win2.c
@@ -19,12 +19,39 @@
 #include <sys/time.h>
 #include <mmsystem.h>
 #include <stdlib.h>
+#include <versionhelpers.h>
+
 #include "timer.h"
 
 #include "config.h"
 
 static LARGE_INTEGER perf_freq;
 
+// ms values
+static int hires_max = 50;
+static int hires_res = 1;
+
+int mp_start_hires_timers(int wait_ms)
+{
+#if !HAVE_UWP
+    // policy: request hires_res ms resolution if wait < hires_max ms
+    if (wait_ms > 0 && wait_ms <= hires_max &&
+        timeBeginPeriod(hires_res) == TIMERR_NOERROR)
+    {
+        return hires_res;
+    }
+#endif
+    return 0;
+}
+
+void mp_end_hires_timers(int res_ms)
+{
+#if !HAVE_UWP
+    if (res_ms > 0)
+        timeEndPeriod(res_ms);
+#endif
+}
+
 void mp_sleep_us(int64_t us)
 {
     if (us < 0)
@@ -34,7 +61,9 @@ void mp_sleep_us(int64_t us)
     // it may take some time until it actually starts to run again
     if (us < 1000)
         us = 1000;
+    int hrt = mp_start_hires_timers(us / 1000);
     Sleep(us / 1000);
+    mp_end_hires_timers(hrt);
 }
 
 uint64_t mp_raw_time_us(void)
@@ -52,7 +81,37 @@ uint64_t mp_raw_time_us(void)
 void mp_raw_time_init(void)
 {
     QueryPerformanceFrequency(&perf_freq);
+
 #if !HAVE_UWP
-    timeBeginPeriod(1); // request 1ms timer resolution
+    // allow (undocumented) control of all the High Res Timers parameters,
+    // for easier experimentation and diagnostic of bug reports.
+    const char *v;
+
+    // 1..1000 ms max timetout for hires (used in "perwait" mode)
+    if ((v = getenv("MPV_HRT_MAX"))) {
+        int hmax = atoi(v);
+        if (hmax >= 1 && hmax <= 1000)
+            hires_max = hmax;
+    }
+
+    // 1..15 ms hires resolution (not used in "never" mode)
+    if ((v = getenv("MPV_HRT_RES"))) {
+        int res = atoi(v);
+        if (res >= 1 && res <= 15)
+            hires_res = res;
+    }
+
+    // "always"/"never"/"perwait"  (or "auto" - same as unset)
+    if (!(v = getenv("MPV_HRT")) || !strcmp(v, "auto"))
+        v = IsWindows10OrGreater() ? "perwait" : "always";
+
+    if (!strcmp(v, "perwait")) {
+        // no-op, already per-wait
+    } else if (!strcmp(v, "never")) {
+        hires_max = 0;
+    } else {  // "always" or unknown value
+        hires_max = 0;
+        timeBeginPeriod(hires_res);
+    }
 #endif
 }