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rtptimedec: fix timestamp decoding when there's an overflow and a negative time diff

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aler9
2022-01-18 11:44:33 +01:00
parent 17f05635dd
commit 68ac48dde7
2 changed files with 38 additions and 15 deletions
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15
pkg/rtptimedec/decoder.go
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@@ -22,17 +22,24 @@ func New(clockRate int) *Decoder {
// Decode decodes a RTP timestamp. // Decode decodes a RTP timestamp.
func (d *Decoder) Decode(ts uint32) time.Duration { func (d *Decoder) Decode(ts uint32) time.Duration {
ts64 := int64(ts) + d.tsAdd ts64 := int64(ts)
if d.tsPrev != nil && (ts64-*d.tsPrev) < -0xFFFF { if d.tsPrev != nil {
ts64 += 0xFFFFFFFF diff := ts64 - *d.tsPrev
switch {
case diff < -0xFFFFFF: // overflow
d.tsAdd += 0xFFFFFFFF d.tsAdd += 0xFFFFFFFF
case diff > 0xFFFFFF: // timestamp overflowed then went back
d.tsAdd -= 0xFFFFFFFF
} }
}
d.tsPrev = &ts64 d.tsPrev = &ts64
if d.tsInitial == nil { if d.tsInitial == nil {
d.tsInitial = &ts64 d.tsInitial = &ts64
} }
return time.Duration(ts64-*d.tsInitial) * time.Second / d.clockRate return time.Duration(ts64+d.tsAdd-*d.tsInitial) * time.Second / d.clockRate
} }

34
pkg/rtptimedec/decoder_test.go
View File

@@ -9,16 +9,32 @@ import (
func TestOverflow(t *testing.T) { func TestOverflow(t *testing.T) {
d := New(90000) d := New(90000)
var pts time.Duration
for _, ts := range []uint32{ pts := d.Decode(4294877295)
4294877296, require.Equal(t, time.Duration(0), pts)
90001,
3240090001, pts = d.Decode(90000)
565122706, require.Equal(t, 2*time.Second, pts)
} {
pts = d.Decode(ts)
} }
require.Equal(t, 15*60*60*time.Second+2*time.Second, pts) func TestOverflowAndBack(t *testing.T) {
d := New(90000)
pts := d.Decode(4294877296)
require.Equal(t, time.Duration(0), pts)
pts = d.Decode(90001)
require.Equal(t, 2*time.Second, pts)
pts = d.Decode(4294877296)
require.Equal(t, time.Duration(0), pts)
pts = d.Decode(4294877296 - 90000)
require.Equal(t, -1*time.Second, pts)
pts = d.Decode(4294877296)
require.Equal(t, time.Duration(0), pts)
pts = d.Decode(90001)
require.Equal(t, 2*time.Second, pts)
} }