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h264: fix 'invalid POC' error (#55)
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bluenviron/mediamtx#1552
bluenviron/mediamtx#1002
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@aler9
aler9 authored Aug 8, 2023
1 parent a381c56 commit ca18675
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Showing 2 changed files with 87 additions and 32 deletions.
67 changes: 40 additions & 27 deletions pkg/codecs/h264/dts_extractor.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -92,7 +92,7 @@ func NewDTSExtractor() *DTSExtractor {
}
}

func (d *DTSExtractor) extractInner(au [][]byte, pts time.Duration) (time.Duration, error) {
func (d *DTSExtractor) extractInner(au [][]byte, pts time.Duration) (time.Duration, bool, error) {
idrPresent := false

for _, nalu := range au {
Expand All @@ -103,7 +103,7 @@ func (d *DTSExtractor) extractInner(au [][]byte, pts time.Duration) (time.Durati
var spsp SPS
err := spsp.Unmarshal(nalu)
if err != nil {
return 0, fmt.Errorf("invalid SPS: %v", err)
return 0, false, fmt.Errorf("invalid SPS: %v", err)
}
d.sps = nalu
d.spsp = &spsp
Expand All @@ -119,40 +119,39 @@ func (d *DTSExtractor) extractInner(au [][]byte, pts time.Duration) (time.Durati
}

if d.spsp == nil {
return 0, fmt.Errorf("SPS not received yet")
return 0, false, fmt.Errorf("SPS not received yet")
}

if d.spsp.PicOrderCntType == 2 {
return pts, nil
return pts, false, nil
}

if d.spsp.PicOrderCntType == 1 {
return 0, fmt.Errorf("pic_order_cnt_type = 1 is not supported yet")
return 0, false, fmt.Errorf("pic_order_cnt_type = 1 is not supported yet")
}

if idrPresent {
d.expectedPOC = 0
} else {
d.expectedPOC += uint32(d.pocIncrement)
d.expectedPOC &= ((1 << (d.spsp.Log2MaxPicOrderCntLsbMinus4 + 4)) - 1)
}

if d.pauseDTS > 0 {
d.pauseDTS--
return d.prevDTS + 1*time.Millisecond, nil
}
d.pauseDTS = 0

if idrPresent {
if !d.prevDTSFilled || d.reorderedFrames == 0 {
return pts, nil
return pts, false, nil
}

return d.prevDTS + (pts-d.prevDTS)/time.Duration(d.reorderedFrames+1), nil
return d.prevDTS + (pts-d.prevDTS)/time.Duration(d.reorderedFrames+1), false, nil
}

d.expectedPOC += uint32(d.pocIncrement)
d.expectedPOC &= ((1 << (d.spsp.Log2MaxPicOrderCntLsbMinus4 + 4)) - 1)

if d.pauseDTS > 0 {
d.pauseDTS--
return d.prevDTS + 1*time.Millisecond, true, nil
}

poc, err := findPictureOrderCount(au, d.spsp)
if err != nil {
return 0, err
return 0, false, err
}

if d.pocIncrement == 2 && (poc%2) != 0 {
Expand All @@ -163,32 +162,46 @@ func (d *DTSExtractor) extractInner(au [][]byte, pts time.Duration) (time.Durati
pocDiff := int(getPictureOrderCountDiff(poc, d.expectedPOC, d.spsp)) + d.reorderedFrames*d.pocIncrement

if pocDiff < 0 {
return 0, fmt.Errorf("invalid POC")
if pocDiff < -20 {
return 0, false, fmt.Errorf("POC difference between frames is too big (%d)", pocDiff)
}

// this happens when there are B-frames immediately following an IDR frame
d.reorderedFrames -= pocDiff
d.pauseDTS = -pocDiff
return d.prevDTS + 1*time.Millisecond, true, nil
}

if pocDiff == 0 {
return pts, nil
return pts, false, nil
}

if pocDiff > 20 {
return 0, false, fmt.Errorf("POC difference between frames is too big (%d)", pocDiff)
}

reorderedFrames := (pocDiff - d.reorderedFrames*d.pocIncrement) / d.pocIncrement
reorderedFrames := (pocDiff)/d.pocIncrement - d.reorderedFrames
if reorderedFrames > d.reorderedFrames {
// reordered frames detected, add them to the count and pause DTS
d.pauseDTS = (reorderedFrames - d.reorderedFrames - 1)
d.reorderedFrames = reorderedFrames
return d.prevDTS + 1*time.Millisecond, nil
return d.prevDTS + 1*time.Millisecond, false, nil
}

return d.prevDTS + (pts-d.prevDTS)*time.Duration(d.pocIncrement)/time.Duration(pocDiff+d.pocIncrement), nil
return d.prevDTS + (pts-d.prevDTS)*time.Duration(d.pocIncrement)/time.Duration(pocDiff+d.pocIncrement), false, nil
}

// Extract extracts the DTS of a access unit.
// Extract extracts the DTS of an access unit.
func (d *DTSExtractor) Extract(au [][]byte, pts time.Duration) (time.Duration, error) {
dts, err := d.extractInner(au, pts)
dts, skipChecks, err := d.extractInner(au, pts)
if err != nil {
return 0, err
}

if dts > pts {
return 0, fmt.Errorf("DTS is greater than PTS")
if !skipChecks {
if dts > pts {
return 0, fmt.Errorf("DTS is greater than PTS")
}
}

if d.prevDTSFilled && dts <= d.prevDTS {
Expand Down
52 changes: 47 additions & 5 deletions pkg/codecs/h264/dts_extractor_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -8,19 +8,19 @@ import (
)

func TestDTSExtractor(t *testing.T) {
type sequenceSample struct {
type sample struct {
au [][]byte
dts time.Duration
pts time.Duration
}

for _, ca := range []struct {
name string
sequence []sequenceSample
sequence []sample
}{
{
"with timing info",
[]sequenceSample{
[]sample{
{
[][]byte{
{ // SPS
Expand Down Expand Up @@ -84,7 +84,7 @@ func TestDTSExtractor(t *testing.T) {
},
{
"no timing info",
[]sequenceSample{
[]sample{
{
[][]byte{
{ // SPS
Expand Down Expand Up @@ -164,7 +164,7 @@ func TestDTSExtractor(t *testing.T) {
},
{
"poc increment = 1",
[]sequenceSample{
[]sample{
{
[][]byte{
{ // SPS
Expand Down Expand Up @@ -197,6 +197,48 @@ func TestDTSExtractor(t *testing.T) {
},
},
},
{
"B-frames after IDR (OBS 29.1.3 QuickSync on Windows)",
[]sample{
{
[][]byte{
{ // SPS
0x27, 0x64, 0x00, 0x2a, 0xac, 0x2d, 0x90, 0x07,
0x80, 0x22, 0x7e, 0x5c, 0x05, 0xa8, 0x08, 0x08,
0x0a, 0x00, 0x00, 0x03, 0x00, 0x02, 0x00, 0x00,
0x03, 0x00, 0xf1, 0xd0, 0x80, 0x04, 0xc4, 0x80,
0x00, 0x09, 0x89, 0x68, 0xde, 0xf7, 0xc1, 0xda,
0x1c, 0x31, 0x92,
},
{ // IDR
0x65, 0x88, 0x80, 0x14, 0x3, 0xff, 0xde, 0x8, 0xe4, 0x74,
},
},
1916 * time.Millisecond,
1916 * time.Millisecond,
},
{ // b-frame
[][]byte{{0x41, 0x9e, 0x3, 0xe4, 0x3f, 0x0, 0x0, 0x3, 0x0, 0x0}},
1917 * time.Millisecond,
1883 * time.Millisecond,
},
{ // b-frame
[][]byte{{0x1, 0x9e, 0x5, 0xd4, 0x7f, 0x0, 0x0, 0x3, 0x0, 0x0}},
1918 * time.Millisecond,
1867 * time.Millisecond,
},
{ // p-frame
[][]byte{{0x1, 0x9e, 0x5, 0xf4, 0x7f, 0x0, 0x0, 0x3, 0x0, 0x0}},
1919 * time.Millisecond,
1899 * time.Millisecond,
},
{ // p-frame
[][]byte{{0x1, 0x9e, 0x5, 0xf4, 0x7f, 0x0, 0x0, 0x3, 0x0, 0x0}},
1920 * time.Millisecond,
1983 * time.Millisecond,
},
},
},
} {
t.Run(ca.name, func(t *testing.T) {
ex := NewDTSExtractor()
Expand Down

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