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