mpegdefs: Simplify PCR/PTS/DTS => GST conversion macros

We know we will not overflow 64 bits, therefore just use direct
multiplication/division instead of the scale method (trims usage from
50 instruction calls to 2/3).

diff --git a/gst/mpegtsdemux/gstmpegdefs.h b/gst/mpegtsdemux/gstmpegdefs.h
index 4f636d9..6f8ebfd 100644 (file)
--- a/gst/mpegtsdemux/gstmpegdefs.h
+++ b/gst/mpegtsdemux/gstmpegdefs.h
@@ -83,10 +83,16 @@
 #define CLOCK_BASE 9LL
 #define CLOCK_FREQ (CLOCK_BASE * 10000)
 
-#define PCRTIME_TO_GSTTIME(time) (gst_util_uint64_scale ((time), \
-            GST_MSECOND/10, 300 * CLOCK_BASE))
-#define MPEGTIME_TO_GSTTIME(time) (gst_util_uint64_scale ((time), \
-            GST_MSECOND/10, CLOCK_BASE))
+/* PCR_TO_GST calculation requires at least 10 extra bits.
+ * Since maximum PCR value is coded with 42 bits, we are
+ * safe to use direct calculation (10+42 < 63)*/
+#define PCRTIME_TO_GSTTIME(t) ((t) * 1000 / 27)
+
+/* MPEG_TO_GST calculation requires at least 17 extra bits (100000)
+ * Since maximum PTS/DTS value is coded with 33bits, we are
+ * safe to use direct calculation (17+33 < 63) */
+#define MPEGTIME_TO_GSTTIME(t) ((t) * 100000 / 9)
+
 #define GSTTIME_TO_MPEGTIME(time) (gst_util_uint64_scale ((time), \
             CLOCK_BASE, GST_MSECOND/10))
 #define GSTTIME_TO_PCRTIME(time) (gst_util_uint64_scale ((time), \