updating duration.String() to handle duration less than a second

go.mod

@@ -2,4 +2,4 @@ module github.com/EurosportDigital/go-dash/v3
 
 go 1.13
 
-replace github.com/zencoder/go-dash/v3 => github.com/EurosportDigital/go-dash v3.0.2
+replace github.com/zencoder/go-dash/v3 => github.com/EurosportDigital/go-dash v3.0.3

mpd/duration.go

@@ -54,13 +54,15 @@ func (d *Duration) String() string {
 	if u < uint64(time.Second) {
 		// Special case: if duration is smaller than a second,
 		// use smaller units, like 1.2ms
-		var prec int
+		//var prec int
 		w--
 		buf[w] = 'S'
 		w--
 		if u == 0 {
 			return "PT0S"
 		}
+		t := time.Duration(*d)
+		return fmt.Sprintf("PT%vS", t.Seconds())
 		/*
 			switch {
 			case u < uint64(Millisecond):
@@ -75,8 +77,8 @@ func (d *Duration) String() string {
 				buf[w] = 'm'
 			}
 		*/
-		w, u = fmtFrac(buf[:w], u, prec)
-		w = fmtInt(buf[:w], u)
+		// w, u = fmtFrac(buf[:w], u, prec)
+		// w = fmtInt(buf[:w], u)
 	} else {
 		w--
 		buf[w] = 'S'

mpd/duration_test.go

@@ -13,6 +13,7 @@ func TestDuration(t *testing.T) {
 		"0s":    "PT0S",
 		"6m16s": "PT6M16S",
 		"1.97s": "PT1.97S",
+		"0.960s": "PT0.96S",
 	}
 	for ins, ex := range in {
 		timeDur, err := time.ParseDuration(ins)