Add DASH streams for VP9 transcoding (#3275)

vendor/github.com/zencoder/go-dash/v3/mpd/events.go

@@ -0,0 +1,18 @@
+package mpd
+
+import "encoding/xml"
+
+type EventStream struct {
+	XMLName     xml.Name `xml:"EventStream"`
+	SchemeIDURI *string  `xml:"schemeIdUri,attr"`
+	Value       *string  `xml:"value,attr,omitempty"`
+	Timescale   *uint    `xml:"timescale,attr"`
+	Events      []Event  `xml:"Event,omitempty"`
+}
+
+type Event struct {
+	XMLName          xml.Name `xml:"Event"`
+	ID               *string  `xml:"id,attr,omitempty"`
+	PresentationTime *uint64  `xml:"presentationTime,attr,omitempty"`
+	Duration         *uint64  `xml:"duration,attr,omitempty"`
+}