systemclock: Fix clock time conversion on Windows/xbox

The returned ratio can be bigger than GST_SECOND, in which case we would
forever return 0 for the system clock time. Even in other cases if it's
close to GST_SECOND it would result in accuracy loss.

Instead of doing the division by GST_CLOCK_TIME_NONE during
initialization once, do it every time the clock time is requested.

Fixes https://gitlab.freedesktop.org/gstreamer/gstreamer/-/issues/575

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/534>

diff --git a/gst/gstsystemclock.c b/gst/gstsystemclock.c
index 91e4078..96341fd 100644 (file)
--- a/gst/gstsystemclock.c
+++ b/gst/gstsystemclock.c
@@ -352,7 +352,6 @@ struct _GstSystemClockPrivate
 
 #ifdef G_OS_WIN32
   LARGE_INTEGER frequency;
-  guint64 ratio;
 #endif                          /* G_OS_WIN32 */
 #ifdef __APPLE__
   struct mach_timebase_info mach_timebase;
@@ -453,10 +452,6 @@ gst_system_clock_init (GstSystemClock * clock)
 
 #ifdef G_OS_WIN32
   QueryPerformanceFrequency (&priv->frequency);
-  /* can be 0 if the hardware does not have hardware support */
-  if (priv->frequency.QuadPart != 0) {
-    priv->ratio = GST_SECOND / priv->frequency.QuadPart;
-  }
 #endif /* G_OS_WIN32 */
 
 #ifdef __APPLE__
@@ -845,7 +840,8 @@ gst_system_clock_get_internal_time (GstClock * clock)
     /* we prefer the highly accurate performance counters on windows */
     QueryPerformanceCounter (&now);
 
-    return now.QuadPart * sysclock->priv->ratio;
+    return gst_util_uint64_scale (now.QuadPart,
+        GST_SECOND, sysclock->priv->frequency.QuadPart);
   } else
 #endif /* G_OS_WIN32 */
 #if !defined HAVE_POSIX_TIMERS || !defined HAVE_CLOCK_GETTIME