2 files changed, 47 insertions, 47 deletions

diff --git a/libs/pbd/pbd/windows_timer_utils.h b/libs/pbd/pbd/windows_timer_utils.h
index 2e4f800bd5..72d3cc5431 100644
--- a/libs/pbd/pbd/windows_timer_utils.h
+++ b/libs/pbd/pbd/windows_timer_utils.h
@@ -26,30 +26,34 @@ namespace PBD {
 namespace MMTIMERS {
 
 /**
- * Set the minimum Multimedia Timer resolution as supported by the system
- * @return true if min timer resolution was successfully set
- *
- * Call reset_resolution to restore old timer resolution
+ * Get the minimum Multimedia Timer resolution as supported by the system
+ * @return true if getting min timer resolution was not successful
  */
-bool set_min_resolution ();
+bool get_min_resolution (uint32_t& timer_resolution_ms);
 
 /**
- * Get current Multimedia Timer resolution
- * @return true if getting the timer value was successful
+ * Set the minimum Multimedia Timer resolution as supported by the system
+ * @return true if setting min timer resolution was successful
  */
-bool get_resolution(uint32_t& timer_resolution_us);
+bool set_min_resolution ();
 
 /**
- * Set current Multimedia Timer resolution
- * @return true if setting the timer value was successful
+ * Set current Multimedia Timer resolution. If the timer resolution has already
+ * been set then reset_resolution() must be called before set_resolution will
+ * succeed.
+ * @return true if setting the timer value was successful, false if setting the
+ * timer resolution failed or the resolution has already been set.
  */
-bool set_resolution(uint32_t timer_resolution_us);
+bool set_resolution(uint32_t timer_resolution_ms);
 
 /**
- * Reset the Multimedia Timer back to what it was originally before
- * setting the timer resolution.
+ * Reset Multimedia Timer resolution. In my testing, if the timer resolution is
+ * set below the default, then resetting the resolution will not reset the
+ * timer resolution back to 15ms. At least it does not reset immediately
+ * even after calling Sleep.
+ * @return true if setting the timer value was successful
  */
-bool reset_resolution ();
+bool reset_resolution();
 
 } // namespace MMTIMERS
 
diff --git a/libs/pbd/windows_timer_utils.cc b/libs/pbd/windows_timer_utils.cc
index fcf8fa8003..d95a69e0c7 100644
--- a/libs/pbd/windows_timer_utils.cc
+++ b/libs/pbd/windows_timer_utils.cc
@@ -29,20 +29,20 @@
 namespace {
 
 UINT&
-old_timer_resolution ()
+timer_resolution ()
 {
 	static UINT timer_res_ms = 0;
 	return timer_res_ms;
 }
 
-} // anon namespace
+}
 
 namespace PBD {
 
 namespace MMTIMERS {
 
 bool
-set_min_resolution ()
+get_min_resolution (uint32_t& min_resolution_ms)
 {
 	TIMECAPS caps;
 
@@ -50,61 +50,57 @@ set_min_resolution ()
 		DEBUG_TIMING ("Could not get timer device capabilities.\n");
 		return false;
 	}
-	return set_resolution(caps.wPeriodMin);
+
+	min_resolution_ms = caps.wPeriodMin;
+	return true;
 }
 
 bool
-set_resolution (uint32_t timer_resolution_ms)
+set_min_resolution ()
 {
-	TIMECAPS caps;
+	uint32_t min_resolution = 0;
 
-	if (timeGetDevCaps (&caps, sizeof(TIMECAPS)) != TIMERR_NOERROR) {
-		DEBUG_TIMING ("Could not get timer device capabilities.\n");
+	if (!get_min_resolution (min_resolution)) {
 		return false;
 	}
 
-	UINT old_timer_res = caps.wPeriodMin;
-
-	if (timeBeginPeriod(timer_resolution_ms) != TIMERR_NOERROR) {
-		DEBUG_TIMING(
-		    string_compose("Could not set minimum timer resolution to %1(ms)\n",
-		                   timer_resolution_ms));
+	if (!set_resolution (min_resolution)) {
 		return false;
 	}
-
-	old_timer_resolution () = old_timer_res;
-
-	DEBUG_TIMING (string_compose ("Multimedia timer resolution set to %1(ms)\n",
-	                              caps.wPeriodMin));
 	return true;
 }
 
 bool
-get_resolution (uint32_t& timer_resolution_ms)
+set_resolution (uint32_t timer_resolution_ms)
 {
-	TIMECAPS caps;
+	if (timer_resolution() != 0) {
+		DEBUG_TIMING(
+		    "Timer resolution must be reset before setting new resolution.\n");
+	}
 
-	if (timeGetDevCaps(&caps, sizeof(TIMECAPS)) != TIMERR_NOERROR) {
-		DEBUG_TIMING ("Could not get timer device capabilities.\n");
+	if (timeBeginPeriod(timer_resolution_ms) != TIMERR_NOERROR) {
+		DEBUG_TIMING(
+		    string_compose("Could not set timer resolution to %1(ms)\n",
+		                   timer_resolution_ms));
 		return false;
 	}
-	timer_resolution_ms = caps.wPeriodMin;
+
+	timer_resolution() = timer_resolution_ms;
+
+	DEBUG_TIMING (string_compose ("Multimedia timer resolution set to %1(ms)\n",
+	                              timer_resolution_ms));
 	return true;
 }
 
 bool
 reset_resolution ()
 {
-	if (old_timer_resolution ()) {
-		if (timeEndPeriod (old_timer_resolution ()) != TIMERR_NOERROR) {
-			DEBUG_TIMING ("Could not reset timer resolution.\n");
-			return false;
-		}
+	// You must match calls to timeBegin/EndPeriod with the same resolution
+	if (timeEndPeriod(timer_resolution()) != TIMERR_NOERROR) {
+		DEBUG_TIMING("Could not reset the Timer resolution.\n");
+		return false;
 	}
-
-	DEBUG_TIMING (string_compose ("Multimedia timer resolution set to %1(ms)\n",
-	                              old_timer_resolution ()));
-
+	timer_resolution() = 0;
 	return true;
 }