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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 { if len(packet.Payload) < 2 {
return false, true return false, true
} }
// Z=0, N=1
if (packet.Payload[0] & 0x88) != 0x08 { if (packet.Payload[0] & 0x88) != 0x08 {
return false, true return false, true
} }
w := (packet.Payload[0] & 0x30) >> 4 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 offset := 0
length := 0 length := 0
for { for {
if len(data) <= offset { if len(data) <= offset {
return nil, 0 return nil, offset, offset > 0
} }
l := data[offset] l := data[offset]
length = length*128 + int(l&0x7f) length |= int(l & 0x7f) << (offset * 7)
offset++ offset++
if (l & 0x80) == 0 { if (l & 0x80) == 0 {
break break
} }
} }
if len(data) < offset+length { 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 offset := 1
if w == 1 { i := 0
obu1 = packet.Payload[1:] for {
} else { obu, length, truncated :=
var o int getObu(packet.Payload[offset:], int(w) == i+1)
obu1, o = getObu(packet.Payload[1:]) if len(obu) < 1 {
if len(obu1) == 0 {
return false, false return false, false
} }
if w == 2 { tpe := (obu[0] & 0x38) >> 3
obu2 = packet.Payload[1+o:] switch i {
} else { case 0:
obu2, _ = getObu(packet.Payload[1+o:]) // 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") { } else if strings.EqualFold(codec, "video/h264") {
if len(packet.Payload) < 1 { if len(packet.Payload) < 1 {
return false, false return false, false
@ -174,9 +175,8 @@ func isKeyframe(codec string, packet *rtp.Packet) (bool, bool) {
return (packet.Payload[1]&0x1F == 7), true return (packet.Payload[1]&0x1F == 7), true
} }
return false, false return false, false
} else {
return false, false
} }
return false, false
} }
var errTruncated = errors.New("truncated packet") var errTruncated = errors.New("truncated packet")