2022年5月4日 (三) 13:04的版本

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

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

C2 -->
C2 必须在 S1之后

<-- s2 必须在C1之后

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

Message Type:

• Limit type

0 - Hard: The peer SHOULD limit its output bandwidth to the indicated window size.
1 - Soft: The peer SHOULD limit its output bandwidth to the the window indicated in this message or the limit already in effect, whichever is smaller.
2 - Dynamic: If the previous Limit Type was Hard, treat this message as though it was marked Hard, otherwise ignore this message.

• RTMP Message Format

Message Header: big-endian format

Message Type[1]
Payload length[3]
Timestamp[4]
Stream ID [3]

Message payload: actual data

• • User Control Message - Event Type

• • Types of command

1. NetConnection

Note:
Audio supported: SUPPORT_SND_ADPCM, MP3, NELLY8, NELLY, G711A, G711U, NELLY16,AAC, SPEEX
Video supported: SUPPORT_VID_SORENSON, HOMEBREW, VP6, VP6ALPHA, HOMEBREWV2, H264
AMF0: AMF0 object encoding supported by Flash 6 and later
AMF3: AMF3 encoding from Flash 9 (AS3)

2. NetStream
1. NetConnection

examples

Use nginx as server and ffmpeg as clients
Ref: cnblogs.com/liangblog/p/11122237.html

• source download:

nginx:

http://nginx.org/download/nginx-1.16.1.tar.gz
wget https://github.com/arut/nginx-rtmp-module/archive/master.zip

openssl:

openssl-1.1.1
openssl-3.0.2

rtmpdump:

git clone https://git.ffmpeg.org/rtmpdump

ffmpeg:

git clone https://git.ffmpeg.org/ffmpeg.git ffmpeg

• build

nginx:

./configure --add-module=nginx-rtmp-module
make
sudo make install

  nginx path prefix: "/usr/local/nginx"
  nginx binary file: "/usr/local/nginx/sbin/nginx"
  nginx modules path: "/usr/local/nginx/modules"
  nginx configuration prefix: "/usr/local/nginx/conf"
  nginx configuration file: "/usr/local/nginx/conf/nginx.conf"
  nginx pid file: "/usr/local/nginx/logs/nginx.pid"
  nginx error log file: "/usr/local/nginx/logs/error.log"
  nginx http access log file: "/usr/local/nginx/logs/access.log"
  nginx http client request body temporary files: "client_body_temp"
  nginx http proxy temporary files: "proxy_temp"
  nginx http fastcgi temporary files: "fastcgi_temp"
  nginx http uwsgi temporary files: "uwsgi_temp"
  nginx http scgi temporary files: "scgi_temp"

Nginx会被安装在/usr/local/nginx目录下
vi /usr/local/nginx/conf/nginx.conf

events   {
  //events模块来用指定nginx的工作模式和工作模式及连接数上限
}
http        {
  //负责HTTP服务器相关属性的配置
}
rtmp {
    server {
        listen 1935;
        buflen 10s;
        application myapp {
            live on;
            max_connections 1024;
        }
        application mgclient {
            live on;
            hls on;
            hls_fragment_naming sequential;
            hls_playlist_length 30s;
            hls_continuous on;
 
        }
    }
}

rtmpdump:

make sys=posix
sudo make install

ffmpeg:

prerequirements: sudo apt install pkg-config
./configure --enable-librtmp
make
sudo make install

• start the server

启动      ：/usr/local/nginx/sbin/nginx
检查配置文件：/usr/local/nginx/sbin/nginx -t
重载配置文件：/usr/local/nginx/sbin/nginx -s reload
重启      : /usr/local/nginx/sbin/nginx -s reopen
停止      ：/usr/local/nginx/sbin/nginx -s stop

• push a mp4 file

ffmpeg -re -i ${HOME}/test.mp4 -vcodec copy -codec copy -f flv rtmp://localhost/myapp/test1

• play a mp4

ffplay rtmp://localhost/myapp/test1

*libRTMP study

Trouble shootings

1. prerequirements:

 openssl library: apt install libssl-dev && sudo apt install OpenSSL
 PCRE library: no
 zlib: sudo apt install zlib1g-dev
 nginx configure:
 ./configure --prefix=/usr/local/nginx --add-module=./nginx-rtmp-module --with-http_ssl_module --without-http_rewrite_module

2. openssl 3.x compiling error

 vi nginx/objs/Makefile => CFLAGS += -Wno-warning -Wno-deprecated-declarations

3. fix librtmp compiling errors:
librtmp/dh.h

typedef struct dh_st {
  MP_t p;
  MP_t g;
  MP_t pub_key;
  MP_t priv_key;
  long length;
} MDH;

librtmp/handshake.h,

#define HMAC_setup(ctx, key, len) { ctx=HMAC_CTX_new(); HMAC_Init_ex(ctx, key, len, EVP_sha256(), 0);}
#define HMAC_crunch(ctx, buf, len) HMAC_Update(ctx, buf, len)
#define HMAC_finish(ctx, dig, dlen) HMAC_Final(ctx, dig, &dlen); HMAC_CTX_free(ctx)
 
static void HMACsha256(const uint8_t *message, size_t messageLen, ...)
static void InitRC4Encryption() {
    HMAC_CTX* ctx;
    HMAC_setup(ctx, secretKey, 128);
    HMAC_crunch(ctx, message, messageLen);
    HMAC_finish(ctx, digest, digestLen);
 
}

librtmp/hashswf.c

struct info
{
  z_stream *zs;
  HMAC_CTX* ctx;
  int first;
  int zlib;
  int size;
};
 
#else   /* USE_OPENSSL */
#include <openssl/ssl.h>
#include <openssl/sha.h>
#include <openssl/hmac.h>
#include <openssl/rc4.h>
#define HMAC_setup(ctx, key, len)       { ctx=HMAC_CTX_new(); HMAC_Init_ex(ctx, (unsigned char *)key, len, EVP_sha256(), 0);}
#define HMAC_crunch(ctx, buf, len)      HMAC_Update(ctx, (unsigned char *)buf, len)
#define HMAC_finish(ctx, dig, dlen)     HMAC_Final(ctx, (unsigned char *)dig, &dlen);
#define HMAC_close(ctx) HMAC_CTX_free(ctx)
#endif

4. For new OS, you will need

- X11: sudo apt install xorg-dev
- ALSA: sudo apt install libpulse-dev
- SDL: ./configure --enable-video-x11 --enable-x11-shared --enable-video-x11-vm --enable-alsa