Add support pipe to exec source

pkg/core/helpers.go

@@ -6,8 +6,15 @@ import (
 	"runtime"
 	"strconv"
 	"strings"
+	"time"
 )
 
+// Now90000 - timestamp for Video (clock rate = 90000 samples per second)
+// same as: uint32(time.Duration(time.Now().UnixNano()) * 90000 / time.Second)
+func Now90000() uint32 {
+	return uint32(time.Duration(time.Now().UnixMilli()) * 90)
+}
+
 const symbols = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-_"
 
 // RandString base10 - numbers, base16 - hex, base36 - digits+letters, base64 - URL safe symbols