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Implement packet pacing.

We used to send all of the packets corresponding to a received packet
as a single burst, which led to persistent packet drops for clients
at the end of the queue.  Pace the writer, which introduces up to 1ms
extra jitter.
This commit is contained in:
Juliusz Chroboczek 2020-06-09 14:52:53 +02:00
parent 2454e33df3
commit 4a526b4133

View file

@ -480,6 +480,7 @@ func newUpConn(c client, id string) (*rtpUpConnection, error) {
type packetIndex struct {
seqno uint16
index uint16
delay uint32
}
func readLoop(conn *rtpUpConnection, track *rtpUpTrack) {
@ -531,15 +532,34 @@ func readLoop(conn *rtpUpConnection, track *rtpUpTrack) {
continue
}
_, rate := track.rate.Estimate()
delay := uint32(rtptime.JiffiesPerSec / 1024)
if rate > 512 {
delay = rtptime.JiffiesPerSec / rate / 2
}
pi := packetIndex{packet.SequenceNumber, index, delay}
select {
case ch <- packetIndex{packet.SequenceNumber, index}:
case ch <- pi:
default:
// the writer is congested
if isvideo {
// the writer is congested. Drop until
// the end of the frame.
// keep dropping until the end of the frame
if isvideo && !packet.Marker {
drop = 7
}
} else {
// try again with half the delay on our side
timer := time.NewTimer(rtptime.ToDuration(
uint64(delay/2),
rtptime.JiffiesPerSec,
))
pi.delay = delay / 2
select {
case ch <- pi:
timer.Stop()
case <-timer.C:
}
}
}
}
@ -598,8 +618,15 @@ func writeLoop(conn *rtpUpConnection, track *rtpUpTrack, ch <-chan packetIndex)
continue
}
kfNeeded := false
var delay time.Duration
if len(local) > 0 {
delay = rtptime.ToDuration(
uint64(pi.delay / uint32(len(local))),
rtptime.JiffiesPerSec,
)
}
kfNeeded := false
for _, l := range local {
err := l.WriteRTP(&packet)
if err != nil {
@ -611,6 +638,9 @@ func writeLoop(conn *rtpUpConnection, track *rtpUpTrack, ch <-chan packetIndex)
continue
}
l.Accumulate(uint32(bytes))
if delay > 0 {
time.Sleep(delay)
}
}
if kfNeeded {