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Rewrite AV1 keyframe detection.

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Metadata OBUs can appear between the sequence header and the first
frame header.
This commit is contained in:
Juliusz Chroboczek 2021-05-16 14:33:57 +02:00
parent 4435a30a53
commit d94e5583cd
1 changed files with 44 additions and 44 deletions
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88
rtpconn/codec.go
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@ -47,71 +47,72 @@ func isKeyframe(codec string, packet *rtp.Packet) (bool, bool) {
if len(packet.Payload) < 2 {
return false, true
}
// Z=0, N=1
if (packet.Payload[0] & 0x88) != 0x08 {
return false, true
}
w := (packet.Payload[0] & 0x30) >> 4
getObu := func(data []byte) ([]byte, int) {
getObu := func(data []byte, last bool) ([]byte, int, bool) {
if last {
return data, len(data), false
}
offset := 0
length := 0
for {
if len(data) <= offset {
return nil, 0
return nil, offset, offset > 0
}
l := data[offset]
length = length*128 + int(l&0x7f)
length |= int(l & 0x7f) << (offset * 7)
offset++
if (l & 0x80) == 0 {
break
}
}
if len(data) < offset+length {
return nil, 0
return data[offset:], len(data), true
}
return data[offset : offset+length], offset + length
return data[offset : offset+length],
offset + length, false
}
var obu1, obu2 []byte
if w == 1 {
obu1 = packet.Payload[1:]
} else {
var o int
obu1, o = getObu(packet.Payload[1:])
if len(obu1) == 0 {
offset := 1
i := 0
for {
obu, length, truncated :=
getObu(packet.Payload[offset:], int(w) == i+1)
if len(obu) < 1 {
return false, false
}
if w == 2 {
obu2 = packet.Payload[1+o:]
} else {
obu2, _ = getObu(packet.Payload[1+o:])
tpe := (obu[0] & 0x38) >> 3
switch i {
case 0:
// OBU_SEQUENCE_HEADER
if tpe != 1 {
return false, true
}
default:
// OBU_FRAME_HEADER or OBU_FRAME
if tpe == 3 || tpe == 6 {
if len(obu) < 2 {
return false, false
}
// show_existing_frame == 0
if (obu[1] & 0x80) != 0 {
return false, true
}
// frame_type == KEY_FRAME
return (obu[1] & 0x60) == 0, true
}
}
if truncated || i >= int(w) {
// the first frame header is in a second
// packet, give up.
return false, false
}
offset += length
i++
}
if len(obu1) < 1 {
return false, false
}
header := obu1[0]
tpe := (header & 0x38) >> 3
if tpe != 1 {
return false, true
}
if w == 1 {
return false, false
}
if len(obu2) < 1 {
return false, false
}
header2 := obu2[0]
tpe2 := (header2 & 0x38) >> 3
if tpe2 != 6 {
return false, false
}
if len(obu2) < 2 {
return false, false
}
if (obu2[1] & 0x80) != 0 {
return false, true
}
return (obu2[1] & 0x60) == 0, false
} else if strings.EqualFold(codec, "video/h264") {
if len(packet.Payload) < 1 {
return false, false
@ -174,9 +175,8 @@ func isKeyframe(codec string, packet *rtp.Packet) (bool, bool) {
return (packet.Payload[1]&0x1F == 7), true
}
return false, false
} else {
return false, false
}
return false, false
}
var errTruncated = errors.New("truncated packet")