Jitter Buffer: Enable setting a minimum length before playout

pkg/jitterbuffer/jitter_buffer.go

@@ -66,6 +66,7 @@ type (
 // provided timestamp
 type JitterBuffer struct {
 	packets      *PriorityQueue
+  minStartCount uint16
 	lastSequence uint16
 	playoutHead  uint16
 	playoutReady bool
@@ -90,13 +91,21 @@ type Stats struct {
 
 // New will initialize a jitter buffer and its associated statistics
 func New(opts ...Option) *JitterBuffer {
-	jb := &JitterBuffer{state: Buffering, stats: Stats{0, 0, 0}, packets: NewQueue(), listeners: make(map[Event][]EventListener)}
+  jb := &JitterBuffer{state: Buffering, stats: Stats{0, 0, 0}, minStartCount: 50, packets: NewQueue(), listeners: make(map[Event][]EventListener)}
 	for _, o := range opts {
 		o(jb)
 	}
 	return jb
 }
 
+// WithMinimumPacketCount will set the required number of packets to be received before 
+// any attempt to pop a packet can succeed
+func WithMinimumPacketCount(count uint16) Option {
+  return func (jb *JitterBuffer) {
+    jb.minStartCount = count
+  }
+}
+
 // Listen will register an event listener
 // The jitter buffer may emit events correspnding, interested listerns should
 // look at Event for available events
@@ -142,7 +151,7 @@ func (jb *JitterBuffer) emit(event Event) {
 
 func (jb *JitterBuffer) updateState() {
 	// For now, we only look at the number of packets captured in the play buffer
-	if jb.packets.Length() >= 50 && jb.state == Buffering {
+	if jb.packets.Length() >= jb.minStartCount && jb.state == Buffering {
 		jb.state = Emitting
 		jb.playoutReady = true
 		jb.emit(BeginPlayback)