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vendor.github.com.pion.rtp.codecs.vp9_packet.go Maven / Gradle / Ivy
package codecs
import (
"github.com/pion/randutil"
)
// Use global random generator to properly seed by crypto grade random.
var globalMathRandomGenerator = randutil.NewMathRandomGenerator() // nolint:gochecknoglobals
// VP9Payloader payloads VP9 packets
type VP9Payloader struct {
pictureID uint16
initialized bool
// InitialPictureIDFn is a function that returns random initial picture ID.
InitialPictureIDFn func() uint16
}
const (
vp9HeaderSize = 3 // Flexible mode 15 bit picture ID
maxSpatialLayers = 5
maxVP9RefPics = 3
)
// Payload fragments an VP9 packet across one or more byte arrays
func (p *VP9Payloader) Payload(mtu uint16, payload []byte) [][]byte {
/*
* https://www.ietf.org/id/draft-ietf-payload-vp9-13.txt
*
* Flexible mode (F=1)
* 0 1 2 3 4 5 6 7
* +-+-+-+-+-+-+-+-+
* |I|P|L|F|B|E|V|Z| (REQUIRED)
* +-+-+-+-+-+-+-+-+
* I: |M| PICTURE ID | (REQUIRED)
* +-+-+-+-+-+-+-+-+
* M: | EXTENDED PID | (RECOMMENDED)
* +-+-+-+-+-+-+-+-+
* L: | TID |U| SID |D| (CONDITIONALLY RECOMMENDED)
* +-+-+-+-+-+-+-+-+ -\
* P,F: | P_DIFF |N| (CONDITIONALLY REQUIRED) - up to 3 times
* +-+-+-+-+-+-+-+-+ -/
* V: | SS |
* | .. |
* +-+-+-+-+-+-+-+-+
*
* Non-flexible mode (F=0)
* 0 1 2 3 4 5 6 7
* +-+-+-+-+-+-+-+-+
* |I|P|L|F|B|E|V|Z| (REQUIRED)
* +-+-+-+-+-+-+-+-+
* I: |M| PICTURE ID | (RECOMMENDED)
* +-+-+-+-+-+-+-+-+
* M: | EXTENDED PID | (RECOMMENDED)
* +-+-+-+-+-+-+-+-+
* L: | TID |U| SID |D| (CONDITIONALLY RECOMMENDED)
* +-+-+-+-+-+-+-+-+
* | TL0PICIDX | (CONDITIONALLY REQUIRED)
* +-+-+-+-+-+-+-+-+
* V: | SS |
* | .. |
* +-+-+-+-+-+-+-+-+
*/
if !p.initialized {
if p.InitialPictureIDFn == nil {
p.InitialPictureIDFn = func() uint16 {
return uint16(globalMathRandomGenerator.Intn(0x7FFF))
}
}
p.pictureID = p.InitialPictureIDFn() & 0x7FFF
p.initialized = true
}
if payload == nil {
return [][]byte{}
}
maxFragmentSize := int(mtu) - vp9HeaderSize
payloadDataRemaining := len(payload)
payloadDataIndex := 0
if min(maxFragmentSize, payloadDataRemaining) <= 0 {
return [][]byte{}
}
var payloads [][]byte
for payloadDataRemaining > 0 {
currentFragmentSize := min(maxFragmentSize, payloadDataRemaining)
out := make([]byte, vp9HeaderSize+currentFragmentSize)
out[0] = 0x90 // F=1 I=1
if payloadDataIndex == 0 {
out[0] |= 0x08 // B=1
}
if payloadDataRemaining == currentFragmentSize {
out[0] |= 0x04 // E=1
}
out[1] = byte(p.pictureID>>8) | 0x80
out[2] = byte(p.pictureID)
copy(out[vp9HeaderSize:], payload[payloadDataIndex:payloadDataIndex+currentFragmentSize])
payloads = append(payloads, out)
payloadDataRemaining -= currentFragmentSize
payloadDataIndex += currentFragmentSize
}
p.pictureID++
if p.pictureID >= 0x8000 {
p.pictureID = 0
}
return payloads
}
// VP9Packet represents the VP9 header that is stored in the payload of an RTP Packet
type VP9Packet struct {
// Required header
I bool // PictureID is present
P bool // Inter-picture predicted frame
L bool // Layer indices is present
F bool // Flexible mode
B bool // Start of a frame
E bool // End of a frame
V bool // Scalability structure (SS) data present
Z bool // Not a reference frame for upper spatial layers
// Recommended headers
PictureID uint16 // 7 or 16 bits, picture ID
// Conditionally recommended headers
TID uint8 // Temporal layer ID
U bool // Switching up point
SID uint8 // Spatial layer ID
D bool // Inter-layer dependency used
// Conditionally required headers
PDiff []uint8 // Reference index (F=1)
TL0PICIDX uint8 // Temporal layer zero index (F=0)
// Scalability structure headers
NS uint8 // N_S + 1 indicates the number of spatial layers present in the VP9 stream
Y bool // Each spatial layer's frame resolution present
G bool // PG description present flag.
NG uint8 // N_G indicates the number of pictures in a Picture Group (PG)
Width []uint16
Height []uint16
PGTID []uint8 // Temporal layer ID of pictures in a Picture Group
PGU []bool // Switching up point of pictures in a Picture Group
PGPDiff [][]uint8 // Reference indecies of pictures in a Picture Group
Payload []byte
videoDepacketizer
}
// Unmarshal parses the passed byte slice and stores the result in the VP9Packet this method is called upon
func (p *VP9Packet) Unmarshal(packet []byte) ([]byte, error) {
if packet == nil {
return nil, errNilPacket
}
if len(packet) < 1 {
return nil, errShortPacket
}
p.I = packet[0]&0x80 != 0
p.P = packet[0]&0x40 != 0
p.L = packet[0]&0x20 != 0
p.F = packet[0]&0x10 != 0
p.B = packet[0]&0x08 != 0
p.E = packet[0]&0x04 != 0
p.V = packet[0]&0x02 != 0
p.Z = packet[0]&0x01 != 0
pos := 1
var err error
if p.I {
pos, err = p.parsePictureID(packet, pos)
if err != nil {
return nil, err
}
}
if p.L {
pos, err = p.parseLayerInfo(packet, pos)
if err != nil {
return nil, err
}
}
if p.F && p.P {
pos, err = p.parseRefIndices(packet, pos)
if err != nil {
return nil, err
}
}
if p.V {
pos, err = p.parseSSData(packet, pos)
if err != nil {
return nil, err
}
}
p.Payload = packet[pos:]
return p.Payload, nil
}
// Picture ID:
//
// +-+-+-+-+-+-+-+-+
// I: |M| PICTURE ID | M:0 => picture id is 7 bits.
// +-+-+-+-+-+-+-+-+ M:1 => picture id is 15 bits.
// M: | EXTENDED PID |
// +-+-+-+-+-+-+-+-+
//
func (p *VP9Packet) parsePictureID(packet []byte, pos int) (int, error) {
if len(packet) <= pos {
return pos, errShortPacket
}
p.PictureID = uint16(packet[pos] & 0x7F)
if packet[pos]&0x80 != 0 {
pos++
if len(packet) <= pos {
return pos, errShortPacket
}
p.PictureID = p.PictureID<<8 | uint16(packet[pos])
}
pos++
return pos, nil
}
func (p *VP9Packet) parseLayerInfo(packet []byte, pos int) (int, error) {
pos, err := p.parseLayerInfoCommon(packet, pos)
if err != nil {
return pos, err
}
if p.F {
return pos, nil
}
return p.parseLayerInfoNonFlexibleMode(packet, pos)
}
// Layer indices (flexible mode):
//
// +-+-+-+-+-+-+-+-+
// L: | T |U| S |D|
// +-+-+-+-+-+-+-+-+
//
func (p *VP9Packet) parseLayerInfoCommon(packet []byte, pos int) (int, error) {
if len(packet) <= pos {
return pos, errShortPacket
}
p.TID = packet[pos] >> 5
p.U = packet[pos]&0x10 != 0
p.SID = (packet[pos] >> 1) & 0x7
p.D = packet[pos]&0x01 != 0
if p.SID >= maxSpatialLayers {
return pos, errTooManySpatialLayers
}
pos++
return pos, nil
}
// Layer indices (non-flexible mode):
//
// +-+-+-+-+-+-+-+-+
// L: | T |U| S |D|
// +-+-+-+-+-+-+-+-+
// | TL0PICIDX |
// +-+-+-+-+-+-+-+-+
//
func (p *VP9Packet) parseLayerInfoNonFlexibleMode(packet []byte, pos int) (int, error) {
if len(packet) <= pos {
return pos, errShortPacket
}
p.TL0PICIDX = packet[pos]
pos++
return pos, nil
}
// Reference indices:
//
// +-+-+-+-+-+-+-+-+ P=1,F=1: At least one reference index
// P,F: | P_DIFF |N| up to 3 times has to be specified.
// +-+-+-+-+-+-+-+-+ N=1: An additional P_DIFF follows
// current P_DIFF.
//
func (p *VP9Packet) parseRefIndices(packet []byte, pos int) (int, error) {
for {
if len(packet) <= pos {
return pos, errShortPacket
}
p.PDiff = append(p.PDiff, packet[pos]>>1)
if packet[pos]&0x01 == 0 {
break
}
if len(p.PDiff) >= maxVP9RefPics {
return pos, errTooManyPDiff
}
pos++
}
pos++
return pos, nil
}
// Scalability structure (SS):
//
// +-+-+-+-+-+-+-+-+
// V: | N_S |Y|G|-|-|-|
// +-+-+-+-+-+-+-+-+ -|
// Y: | WIDTH | (OPTIONAL) .
// + + .
// | | (OPTIONAL) .
// +-+-+-+-+-+-+-+-+ . N_S + 1 times
// | HEIGHT | (OPTIONAL) .
// + + .
// | | (OPTIONAL) .
// +-+-+-+-+-+-+-+-+ -|
// G: | N_G | (OPTIONAL)
// +-+-+-+-+-+-+-+-+ -|
// N_G: | T |U| R |-|-| (OPTIONAL) .
// +-+-+-+-+-+-+-+-+ -| . N_G times
// | P_DIFF | (OPTIONAL) . R times .
// +-+-+-+-+-+-+-+-+ -| -|
//
func (p *VP9Packet) parseSSData(packet []byte, pos int) (int, error) {
if len(packet) <= pos {
return pos, errShortPacket
}
p.NS = packet[pos] >> 5
p.Y = packet[pos]&0x10 != 0
p.G = (packet[pos]>>1)&0x7 != 0
pos++
NS := p.NS + 1
p.NG = 0
if p.Y {
p.Width = make([]uint16, NS)
p.Height = make([]uint16, NS)
for i := 0; i < int(NS); i++ {
p.Width[i] = uint16(packet[pos])<<8 | uint16(packet[pos+1])
pos += 2
p.Height[i] = uint16(packet[pos])<<8 | uint16(packet[pos+1])
pos += 2
}
}
if p.G {
p.NG = packet[pos]
pos++
}
for i := 0; i < int(p.NG); i++ {
p.PGTID = append(p.PGTID, packet[pos]>>5)
p.PGU = append(p.PGU, packet[pos]&0x10 != 0)
R := (packet[pos] >> 2) & 0x3
pos++
p.PGPDiff = append(p.PGPDiff, []uint8{})
for j := 0; j < int(R); j++ {
p.PGPDiff[i] = append(p.PGPDiff[i], packet[pos])
pos++
}
}
return pos, nil
}
// VP9PartitionHeadChecker is obsolete
type VP9PartitionHeadChecker struct{}
// IsPartitionHead checks whether if this is a head of the VP9 partition
func (*VP9Packet) IsPartitionHead(payload []byte) bool {
if len(payload) < 1 {
return false
}
return (payload[0] & 0x08) != 0
}
