RTMP study notes RTMP study notes 0

Ref: https://www.adobe.com/devnet/rtmp.html
Handshaking Sequence

---

uninitialized ----

C0 -->
C1 -->
<-- S0 必须在 C0或C1 之后
<-- S1 必须在 C0或C1 之后

---

version sent -----

C2 -->
C2 必须在 S1之后

---

Ack sent -----

<-- s2 必须在C1之后

---

Handshake Done ----

data -->
data必须在S2之后

  <-- data 必须在c2 之后

---

C0-> RTMP version 8 bits (=3)

 <- S0 RTMP version 8 bit (=3)

C1,S1 1536 bytes

time[4]:   stream 的参考基准时间
zero[4]:0
random bytes[1528]  乱数token

C2,S2 1536 bytes

time[4]:   C2: S1 的时间; S2: C1 的时间
time2[4]:  读取S1/C1的时间
random bytes[1528]: C1/S1的乱数token

Chunk:
| Basic Header | Message Header | Extended Timestamp | Chunk Data |
+--------------+----------------+--------------------+--------------+
Basic Header: 1~3 bytes, Chunk Stream ID + chunk type
Message Header:0,3,7, or 11 bytes,message的type
Extended Timestamp: 0 or 4 bytes
Chunk header = Basic Header + Message Header + Extended Timestamp
Chunk data: variable size.
Chunk Stream ID: 3~65599,

 0n = 64+n (64~319)
 1mn = 64+m + n*256 (64~65599)
 n (n !=0,1,2 one byte) (3~63)
 2 is reserved for level control

chunk type 高2位:format of Message header

Type 0: 11 byte 用于stream 开头
 timestamp[3]: 发送时间, 0xffffff  使用Extended Timestamp [32bits]
 message length[3]
 message type id[1]
 message stream id[4]
Type 1: 7 bytes
 timestamp delta[3]
 message length[3]
 message type id[1]
Type 2: 3 bytes ID 与长度跟前个chunk 同
 timestamp delta[3]
Type 3: no message header. timestamp , ID 与长度跟前个chunk 同

message type id

1,2,3,5,6 for protocol control message
8: audio
9: video

Protocol Control Messages
message stream ID 0: control stream
chunk stream ID 2: used in control stream
message type id

ID	Name	Fields	size	Meaning
1	Set Chunk Size	maximum chunk size	32 bits	Set maximum chunk size (1~0x7FFFFFFF)
2	Abort Message	chunk stream ID	32 bits	chunk stream ID message to be discard
3	Acknowledgement	sequnce number	32 bits	This field holds the number of bytes received so far.
5	Window Acknowledgement Size	window size	32 bits	inform the peer of the window size to use between sending acknowledgments
6	Set Peer Bandwidth	Acknowledgement Window size	32	sends this message to limit the output			Set Peer Bandwidth	Acknowledgement Window size	32	sends this message to limit the output bandwidth of its peer.