mirror of
https://github.com/Monibuca/plugin-rtmp.git
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124 lines
4.4 KiB
Go
124 lines
4.4 KiB
Go
package rtmp
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import (
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"encoding/binary"
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"m7s.live/engine/v4/util"
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)
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// RTMP协议中基本的数据单元称为消息(Message).
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// 当RTMP协议在互联网中传输数据的时候,消息会被拆分成更小的单元,称为消息块(Chunk).
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// 在网络上传输数据时,消息需要被拆分成较小的数据块,才适合在相应的网络环境上传输.
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// 理论上Type 0, 1, 2的Chunk都可以使用Extended Timestamp来传递时间
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// Type 3由于严禁携带Extened Timestamp字段.但实际上只有Type 0才需要带此字段.
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// 这是因为,对Type 1, 2来说,其时间为一个差值,一般肯定小于0x00FFFFF
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// 对于除Audio,Video以外的基它Message,其时间字段都可以是置为0的，似乎没有被用到.
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// 只有在发送视频和音频数据时,才需要特别的考虑TimeStamp字段.基本依据是,要以HandShake时为起始点0来计算时间.
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// 一般来说,建立一个相对时间,把一个视频帧的TimeStamp特意的在当前时间的基础上延迟3秒,则可以达到缓存的效果
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const (
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RTMP_CHUNK_HEAD_12 = 0 << 6 // Chunk Basic Header = (Chunk Type << 6) | Chunk Stream ID.
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RTMP_CHUNK_HEAD_8 = 1 << 6
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RTMP_CHUNK_HEAD_4 = 2 << 6
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RTMP_CHUNK_HEAD_1 = 3 << 6
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)
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type Chunk struct {
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ChunkHeader
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Body []byte
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MsgData RtmpMessage
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}
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func (c *Chunk) Encode(msg RtmpMessage) {
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c.MsgData = msg
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c.Body = msg.Encode()
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c.MessageLength = uint32(len(c.Body))
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}
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type ChunkHeader struct {
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ChunkBasicHeader
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ChunkMessageHeader
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// Extended Timestamp (0 or 4 bytes): This field is present in certain
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// circumstances depending on the encoded timestamp or timestamp
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// delta field in the Chunk Message header. See Section 5.3.1.3 for
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// more information
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ExtendTimestamp uint32 `json:",omitempty"` // 标识该字段的数据可忽略
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}
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// Basic Header (1 to 3 bytes) : This field encodes the chunk stream ID
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// and the chunk type. Chunk type determines the format of the
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// encoded message header. The length(Basic Header) depends entirely on the chunk
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// stream ID, which is a variable-length field.
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type ChunkBasicHeader struct {
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ChunkStreamID uint32 `json:""` // 6 bit. 3 ~ 65559, 0,1,2 reserved
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ChunkType byte `json:""` // 2 bit.
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}
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// Message Header (0, 3, 7, or 11 bytes): This field encodes
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// information about the message being sent (whether in whole or in
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// part). The length can be determined using the chunk type
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// specified in the chunk header.
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type ChunkMessageHeader struct {
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Timestamp uint32 `json:""` // 3 byte
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MessageLength uint32 `json:""` // 3 byte
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MessageTypeID byte `json:""` // 1 byte
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MessageStreamID uint32 `json:""` // 4 byte
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}
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// ChunkBasicHeader会决定ChunkMessgaeHeader,ChunkMessgaeHeader有4种(0,3,7,11 Bytes),因此可能有4种头.
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// 1 -> ChunkBasicHeader(1) + ChunkMessageHeader(0)
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// 4 -> ChunkBasicHeader(1) + ChunkMessageHeader(3)
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// 8 -> ChunkBasicHeader(1) + ChunkMessageHeader(7)
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// 12 -> ChunkBasicHeader(1) + ChunkMessageHeader(11)
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func (nc *NetConnection) encodeChunk12(head *ChunkHeader) []byte {
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b := util.Buffer(make([]byte, 0, 16))
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b.WriteByte(byte(RTMP_CHUNK_HEAD_12 + head.ChunkStreamID))
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b.WriteUint24(head.Timestamp)
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b.WriteUint24(head.MessageLength)
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b.WriteByte(head.MessageTypeID)
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binary.LittleEndian.PutUint32(b.Malloc(4), head.MessageStreamID)
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if head.ChunkMessageHeader.Timestamp == 0xffffff {
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binary.LittleEndian.PutUint32(b.Malloc(4), head.ExtendTimestamp)
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}
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return b
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}
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func (nc *NetConnection) encodeChunk8(head *ChunkHeader) []byte {
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b := util.Buffer(make([]byte, 0, 8))
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b.WriteByte(byte(RTMP_CHUNK_HEAD_8 + head.ChunkStreamID))
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b.WriteUint24(head.Timestamp)
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b.WriteUint24(head.MessageLength)
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b.WriteByte(head.MessageTypeID)
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return b
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}
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// func (nc *NetConnection) encodeChunk4(head *ChunkHeader, payload []byte, size int) (need []byte, err error) {
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// if size > RTMP_MAX_CHUNK_SIZE || payload == nil || len(payload) == 0 {
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// return nil, errors.New("chunk error")
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// }
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// b := make([]byte, 4)
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// //chunkBasicHead
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// b[0] = byte(RTMP_CHUNK_HEAD_4 + head.ChunkStreamID)
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// util.PutBE(b[1:4], head.Timestamp)
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// nc.Write(b)
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// nc.writeSeqNum += 4
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// if len(payload) > size {
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// nc.Write(payload[0:size])
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// nc.writeSeqNum += uint32(size)
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// need = payload[size:]
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// } else {
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// nc.Write(payload)
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// nc.writeSeqNum += uint32(len(payload))
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// }
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// return
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// }
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func (nc *NetConnection) encodeChunk1(head *ChunkHeader) []byte {
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return []byte{byte(RTMP_CHUNK_HEAD_1 + head.ChunkStreamID)}
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}
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