mirror of https://github.com/jech/galene.git
55 lines
1.1 KiB
Go
55 lines
1.1 KiB
Go
// package jitter implements a jitter estimator
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package jitter
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import (
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"sync/atomic"
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"github.com/jech/galene/rtptime"
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)
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type Estimator struct {
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hz uint32
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timestamp uint32
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time uint32
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jitter uint32 // atomic
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}
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// New returns a new jitter estimator that uses units of 1/hz seconds.
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func New(hz uint32) *Estimator {
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return &Estimator{hz: hz}
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}
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func (e *Estimator) accumulate(timestamp, now uint32) {
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if e.time == 0 {
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e.timestamp = timestamp
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e.time = now
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}
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d := uint32((e.time - now) - (e.timestamp - timestamp))
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if d&0x80000000 != 0 {
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d = uint32(-int32(d))
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}
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oldjitter := atomic.LoadUint32(&e.jitter)
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jitter := (oldjitter*15 + d) / 16
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atomic.StoreUint32(&e.jitter, jitter)
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e.timestamp = timestamp
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e.time = now
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}
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// Accumulate accumulates a new sample for the jitter estimator.
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func (e *Estimator) Accumulate(timestamp uint32) {
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e.accumulate(timestamp, uint32(rtptime.Now(e.hz)))
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}
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// Jitter returns the estimated jitter, in units of 1/hz seconds.
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// This function is safe to call concurrently.
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func (e *Estimator) Jitter() uint32 {
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return atomic.LoadUint32(&e.jitter)
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}
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func (e *Estimator) HZ() uint32 {
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return e.hz
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}
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