1 files changed, 159 insertions, 0 deletions
diff --git a/vendor/github.com/pion/interceptor/pkg/report/receiver_stream.go b/vendor/github.com/pion/interceptor/pkg/report/receiver_stream.go
new file mode 100644
index 0000000..569715d
--- /dev/null
+++ b/vendor/github.com/pion/interceptor/pkg/report/receiver_stream.go
@@ -0,0 +1,159 @@
+package report
+
+import (
+	"math/rand"
+	"sync"
+	"time"
+
+	"github.com/pion/rtcp"
+	"github.com/pion/rtp"
+)
+
+type receiverStream struct {
+	ssrc         uint32
+	receiverSSRC uint32
+	clockRate    float64
+
+	m                    sync.Mutex
+	size                 uint16
+	packets              []uint64
+	started              bool
+	seqnumCycles         uint16
+	lastSeqnum           uint16
+	lastReportSeqnum     uint16
+	lastRTPTimeRTP       uint32
+	lastRTPTimeTime      time.Time
+	jitter               float64
+	lastSenderReport     uint32
+	lastSenderReportTime time.Time
+	totalLost            uint32
+}
+
+func newReceiverStream(ssrc uint32, clockRate uint32) *receiverStream {
+	receiverSSRC := rand.Uint32() // #nosec
+	return &receiverStream{
+		ssrc:         ssrc,
+		receiverSSRC: receiverSSRC,
+		clockRate:    float64(clockRate),
+		size:         128,
+		packets:      make([]uint64, 128),
+	}
+}
+
+func (stream *receiverStream) processRTP(now time.Time, pkt *rtp.Packet) {
+	stream.m.Lock()
+	defer stream.m.Unlock()
+
+	if !stream.started { // first frame
+		stream.started = true
+		stream.setReceived(pkt.SequenceNumber)
+		stream.lastSeqnum = pkt.SequenceNumber
+		stream.lastReportSeqnum = pkt.SequenceNumber - 1
+		stream.lastRTPTimeRTP = pkt.Timestamp
+		stream.lastRTPTimeTime = now
+	} else { // following frames
+		stream.setReceived(pkt.SequenceNumber)
+
+		diff := int32(pkt.SequenceNumber) - int32(stream.lastSeqnum)
+		if diff > 0 || diff < -0x0FFF {
+			// overflow
+			if diff < -0x0FFF {
+				stream.seqnumCycles++
+			}
+
+			// set missing packets as missing
+			for i := stream.lastSeqnum + 1; i != pkt.SequenceNumber; i++ {
+				stream.delReceived(i)
+			}
+
+			stream.lastSeqnum = pkt.SequenceNumber
+		}
+
+		// compute jitter
+		// https://tools.ietf.org/html/rfc3550#page-39
+		D := now.Sub(stream.lastRTPTimeTime).Seconds()*stream.clockRate -
+			(float64(pkt.Timestamp) - float64(stream.lastRTPTimeRTP))
+		if D < 0 {
+			D = -D
+		}
+		stream.jitter += (D - stream.jitter) / 16
+		stream.lastRTPTimeRTP = pkt.Timestamp
+		stream.lastRTPTimeTime = now
+	}
+}
+
+func (stream *receiverStream) setReceived(seq uint16) {
+	pos := seq % stream.size
+	stream.packets[pos/64] |= 1 << (pos % 64)
+}
+
+func (stream *receiverStream) delReceived(seq uint16) {
+	pos := seq % stream.size
+	stream.packets[pos/64] &^= 1 << (pos % 64)
+}
+
+func (stream *receiverStream) getReceived(seq uint16) bool {
+	pos := seq % stream.size
+	return (stream.packets[pos/64] & (1 << (pos % 64))) != 0
+}
+
+func (stream *receiverStream) processSenderReport(now time.Time, sr *rtcp.SenderReport) {
+	stream.m.Lock()
+	defer stream.m.Unlock()
+
+	stream.lastSenderReport = uint32(sr.NTPTime >> 16)
+	stream.lastSenderReportTime = now
+}
+
+func (stream *receiverStream) generateReport(now time.Time) *rtcp.ReceiverReport {
+	stream.m.Lock()
+	defer stream.m.Unlock()
+
+	totalSinceReport := stream.lastSeqnum - stream.lastReportSeqnum
+	totalLostSinceReport := func() uint32 {
+		if stream.lastSeqnum == stream.lastReportSeqnum {
+			return 0
+		}
+
+		ret := uint32(0)
+		for i := stream.lastReportSeqnum + 1; i != stream.lastSeqnum; i++ {
+			if !stream.getReceived(i) {
+				ret++
+			}
+		}
+		return ret
+	}()
+	stream.totalLost += totalLostSinceReport
+
+	// allow up to 24 bits
+	if totalLostSinceReport > 0xFFFFFF {
+		totalLostSinceReport = 0xFFFFFF
+	}
+	if stream.totalLost > 0xFFFFFF {
+		stream.totalLost = 0xFFFFFF
+	}
+
+	r := &rtcp.ReceiverReport{
+		SSRC: stream.receiverSSRC,
+		Reports: []rtcp.ReceptionReport{
+			{
+				SSRC:               stream.ssrc,
+				LastSequenceNumber: uint32(stream.seqnumCycles)<<16 | uint32(stream.lastSeqnum),
+				LastSenderReport:   stream.lastSenderReport,
+				FractionLost:       uint8(float64(totalLostSinceReport*256) / float64(totalSinceReport)),
+				TotalLost:          stream.totalLost,
+				Delay: func() uint32 {
+					if stream.lastSenderReportTime.IsZero() {
+						return 0
+					}
+					return uint32(now.Sub(stream.lastSenderReportTime).Seconds() * 65536)
+				}(),
+				Jitter: uint32(stream.jitter),
+			},
+		},
+	}
+
+	stream.lastReportSeqnum = stream.lastSeqnum
+
+	return r
+}