直播：后台 JWT 推流、前台画中画；WebRTC 服务与 Nginx WebSocket 代理

Made-with: Cursor

server/vendor/github.com/pion/rtp/codecs/av1_packet.go

@@ -0,0 +1,204 @@
+// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+package codecs
+
+import (
+	"github.com/pion/rtp/codecs/av1/obu"
+)
+
+const (
+	zMask     = byte(0b10000000)
+	zBitshift = 7
+
+	yMask     = byte(0b01000000)
+	yBitshift = 6
+
+	wMask     = byte(0b00110000)
+	wBitshift = 4
+
+	nMask     = byte(0b00001000)
+	nBitshift = 3
+
+	obuFrameTypeMask     = byte(0b01111000)
+	obuFrameTypeBitshift = 3
+
+	obuFameTypeSequenceHeader = 1
+
+	av1PayloaderHeadersize = 1
+
+	leb128Size = 1
+)
+
+// AV1Payloader payloads AV1 packets
+type AV1Payloader struct {
+	sequenceHeader []byte
+}
+
+// Payload fragments a AV1 packet across one or more byte arrays
+// See AV1Packet for description of AV1 Payload Header
+func (p *AV1Payloader) Payload(mtu uint16, payload []byte) (payloads [][]byte) {
+	payloadDataIndex := 0
+	payloadDataRemaining := len(payload)
+
+	// Payload Data and MTU is non-zero
+	if mtu <= 0 || payloadDataRemaining <= 0 {
+		return payloads
+	}
+
+	// Cache Sequence Header and packetize with next payload
+	frameType := (payload[0] & obuFrameTypeMask) >> obuFrameTypeBitshift
+	if frameType == obuFameTypeSequenceHeader {
+		p.sequenceHeader = payload
+		return
+	}
+
+	for payloadDataRemaining > 0 {
+		obuCount := byte(1)
+		metadataSize := av1PayloaderHeadersize
+		if len(p.sequenceHeader) != 0 {
+			obuCount++
+			metadataSize += leb128Size + len(p.sequenceHeader)
+		}
+
+		out := make([]byte, min(int(mtu), payloadDataRemaining+metadataSize))
+		outOffset := av1PayloaderHeadersize
+		out[0] = obuCount << wBitshift
+
+		if obuCount == 2 {
+			// This Payload contain the start of a Coded Video Sequence
+			out[0] ^= nMask
+
+			out[1] = byte(obu.EncodeLEB128(uint(len(p.sequenceHeader))))
+			copy(out[2:], p.sequenceHeader)
+
+			outOffset += leb128Size + len(p.sequenceHeader)
+
+			p.sequenceHeader = nil
+		}
+
+		outBufferRemaining := len(out) - outOffset
+		copy(out[outOffset:], payload[payloadDataIndex:payloadDataIndex+outBufferRemaining])
+		payloadDataRemaining -= outBufferRemaining
+		payloadDataIndex += outBufferRemaining
+
+		// Does this Fragment contain an OBU that started in a previous payload
+		if len(payloads) > 0 {
+			out[0] ^= zMask
+		}
+
+		// This OBU will be continued in next Payload
+		if payloadDataRemaining != 0 {
+			out[0] ^= yMask
+		}
+
+		payloads = append(payloads, out)
+	}
+
+	return payloads
+}
+
+// AV1Packet represents a depacketized AV1 RTP Packet
+/*
+*  0 1 2 3 4 5 6 7
+* +-+-+-+-+-+-+-+-+
+* |Z|Y| W |N|-|-|-|
+* +-+-+-+-+-+-+-+-+
+**/
+// https://aomediacodec.github.io/av1-rtp-spec/#44-av1-aggregation-header
+type AV1Packet struct {
+	// Z: MUST be set to 1 if the first OBU element is an
+	//    OBU fragment that is a continuation of an OBU fragment
+	//    from the previous packet, and MUST be set to 0 otherwise.
+	Z bool
+
+	// Y: MUST be set to 1 if the last OBU element is an OBU fragment
+	//    that will continue in the next packet, and MUST be set to 0 otherwise.
+	Y bool
+
+	// W: two bit field that describes the number of OBU elements in the packet.
+	//    This field MUST be set equal to 0 or equal to the number of OBU elements
+	//    contained in the packet. If set to 0, each OBU element MUST be preceded by
+	//    a length field. If not set to 0 (i.e., W = 1, 2 or 3) the last OBU element
+	//    MUST NOT be preceded by a length field. Instead, the length of the last OBU
+	//    element contained in the packet can be calculated as follows:
+	// Length of the last OBU element =
+	//    length of the RTP payload
+	//  - length of aggregation header
+	//  - length of previous OBU elements including length fields
+	W byte
+
+	// N: MUST be set to 1 if the packet is the first packet of a coded video sequence, and MUST be set to 0 otherwise.
+	N bool
+
+	// Each AV1 RTP Packet is a collection of OBU Elements. Each OBU Element may be a full OBU, or just a fragment of one.
+	// AV1Frame provides the tools to construct a collection of OBUs from a collection of OBU Elements
+	OBUElements [][]byte
+
+	videoDepacketizer
+}
+
+// Unmarshal parses the passed byte slice and stores the result in the AV1Packet this method is called upon
+func (p *AV1Packet) Unmarshal(payload []byte) ([]byte, error) {
+	if payload == nil {
+		return nil, errNilPacket
+	} else if len(payload) < 2 {
+		return nil, errShortPacket
+	}
+
+	p.Z = ((payload[0] & zMask) >> zBitshift) != 0
+	p.Y = ((payload[0] & yMask) >> yBitshift) != 0
+	p.N = ((payload[0] & nMask) >> nBitshift) != 0
+	p.W = (payload[0] & wMask) >> wBitshift
+
+	if p.Z && p.N {
+		return nil, errIsKeyframeAndFragment
+	}
+
+	if !p.zeroAllocation {
+		obuElements, err := p.parseBody(payload[1:])
+		if err != nil {
+			return nil, err
+		}
+		p.OBUElements = obuElements
+	}
+
+	return payload[1:], nil
+}
+
+func (p *AV1Packet) parseBody(payload []byte) ([][]byte, error) {
+	if p.OBUElements != nil {
+		return p.OBUElements, nil
+	}
+
+	obuElements := [][]byte{}
+
+	var obuElementLength, bytesRead uint
+	currentIndex := uint(0)
+	for i := 1; ; i++ {
+		if currentIndex == uint(len(payload)) {
+			break
+		}
+
+		// If W bit is set the last OBU Element will have no length header
+		if byte(i) == p.W {
+			bytesRead = 0
+			obuElementLength = uint(len(payload)) - currentIndex
+		} else {
+			var err error
+			obuElementLength, bytesRead, err = obu.ReadLeb128(payload[currentIndex:])
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		currentIndex += bytesRead
+		if uint(len(payload)) < currentIndex+obuElementLength {
+			return nil, errShortPacket
+		}
+		obuElements = append(obuElements, payload[currentIndex:currentIndex+obuElementLength])
+		currentIndex += obuElementLength
+	}
+
+	return obuElements, nil
+}