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53 lines
1.0 KiB
Go
53 lines
1.0 KiB
Go
package common
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// DTSEstimator is a DTS estimator.
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type DTSEstimator struct {
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prevDTS uint32
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prevPTS uint32
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prevPrevPTS uint32
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dts func(uint32) uint32
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}
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func (d *DTSEstimator) _dts(pts uint32) uint32 {
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// P or I frame
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if pts > d.prevPTS {
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// previous frame was B
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// use the DTS of the previous frame
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if d.prevPTS < d.prevPrevPTS {
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return d.prevPTS
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}
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// previous frame was P or I
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// use two frames ago plus a small quantity
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// to avoid non-monotonous DTS with B-frames
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return d.prevPrevPTS + 1
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}
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// B Frame
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// increase by a small quantity
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return d.prevDTS + 1
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}
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// NewDTSEstimator allocates a DTSEstimator.
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func NewDTSEstimator() *DTSEstimator {
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result := &DTSEstimator{}
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result.dts = func(pts uint32) uint32 {
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if pts > 0 {
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result.dts = result._dts
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}
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return pts
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}
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return result
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}
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// Feed provides PTS to the estimator, and returns the estimated DTS.
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func (d *DTSEstimator) Feed(pts uint32) uint32 {
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dts := d.dts(pts)
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d.prevPrevPTS = d.prevPTS
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d.prevPTS = pts
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d.prevDTS = dts
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return dts
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}
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