Ready-to-use SRT / WebRTC / RTSP / RTMP / LL-HLS media server and media proxy that allows to read, publish, proxy, record and playback video and audio streams.
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package h264
import (
"time"
)
// DTSEstimator is a DTS estimator.
type DTSEstimator struct {
initializing int
prevDTS time.Duration
prevPTS time.Duration
prevPrevPTS time.Duration
}
// NewDTSEstimator allocates a DTSEstimator.
func NewDTSEstimator() *DTSEstimator {
return &DTSEstimator{
initializing: 2,
}
}
// Feed provides PTS to the estimator, and returns the estimated DTS.
func (d *DTSEstimator) Feed(pts time.Duration) time.Duration {
if d.initializing > 0 {
d.initializing--
dts := d.prevDTS + time.Millisecond
d.prevPrevPTS = d.prevPTS
d.prevPTS = pts
d.prevDTS = dts
return dts
}
dts := func() time.Duration {
// P or I frame
if pts > d.prevPTS {
// previous frame was B
// use the DTS of the previous frame
if d.prevPTS < d.prevPrevPTS {
return d.prevPTS
}
// previous frame was P or I
// use two frames ago plus a small quantity
// to avoid non-monotonous DTS with B-frames
return d.prevPrevPTS + time.Millisecond
}
// B Frame
// do not increase
return d.prevDTS + time.Millisecond
}()
d.prevPrevPTS = d.prevPTS
d.prevPTS = pts
d.prevDTS = dts
return dts
}