一、Nginx服务器搭建
因为要将处理过的图片串成rtmp码流，因此，需要搭建一个rtmp服务器，常用的方案是Nginx服务器。
1.1 安装依赖
sudo apt-get update
sudo apt-get install -y openssl libssl-dev libpcre3 libpcre3-dev zlib1g-dev
sudo apt-get install -y autoconf automake build-essential git libass-dev libfreetype6-dev libsdl2-dev libtheora-dev libtool libva-dev libvdpau-dev libvorbis-dev libxcb1-dev libxcb-shm0-dev libxcb-xfixes0-dev pkg-config texinfo wget zlib1g-dev
sudo apt-get install -y ffmpeg
1.2 编译源码
- 在工作空间下，新建一个nginx文件夹，用来存放需要下载nginx和nginx-rtmp-module两个安装包源码。
- nginx下载链接，nginx-rtmp-module下载链接。
- 解压文件，生成nginx-1.18.0文件夹，生成nginx-rtmp-module文件夹。
- 然后编译安装nginx，cd进nginx的目录。
cd nginx-1.18.0
./configure --add-module=../nginx-rtmp-module
make -j4
sudo make install
1.3 测试nginx
直接运行以下命令：
sudo /usr/local/nginx/sbin/nginx
在浏览器中输入localhost：80（或者服务器的IP），看到如下画面，表示安装成功。
无人机之眼 | ROS图像RTMP协议推流到地面站，CPU表示软件解码
1.4 配置
编辑
/usr/local/nginx/conf/nginx.conf文件（）。sudo gedit /usr/local/nginx/conf/nginx.conf
#user nobody;
worker_processes 1;
#error_log logs/error.log;
#error_log logs/error.log notice;
#error_log logs/error.log info;
#pid logs/nginx.pid;
events {
worker_connections 1024;
}
rtmp {
server {
listen 1935; # 服务端口--默认
chunk_size 4096; # 数据传输块的大小--默认
# 设置直播的application名称是live
application live {
live on; # live on表示开启直播模式
}
}
}
http {
include mime.types;
default_type application/octet-stream;
#log_format main '$remote_addr - $remote_user [$time_local] "$request" '
# '$status $body_bytes_sent "$http_referer" '
# '"$http_user_agent" "$http_x_forwarded_for"';
#access_log logs/access.log main;
sendfile on;
#tcp_nopush on;
#keepalive_timeout 0;
keepalive_timeout 65;
#gzip on;
server {
listen 80;
server_name localhost;
#charset koi8-r;
#access_log logs/host.access.log main;
location / {
root html;
index index.html index.htm;
}
location /info {
rtmp_stat all;
rtmp_stat_stylesheet stat.xsl;
}
location /stat.xsl {
root html;
}
#error_page 404 /404.html;
# redirect server error pages to the static page /50x.html
#
error_page 500 502 503 504 /50x.html;
location = /50x.html {
root html;
}
}
}
配置完之后，需要重启nginx：
sudo cp nginx-rtmp-module/stat.xsl /usr/local/nginx/html/
sudo /usr/local/nginx/sbin/nginx -s reload
然后在浏览器中输入localhost:80/info可看到如下画面：
无人机之眼 | ROS图像RTMP协议推流到地面站，CPU表示软件解码
至此，完成了rtmp-nginx服务器的全部配置。
1.5 让系统启动时自动加载nginx服务
- 首先需要安装sysv-rc-conf：
sudo apt-get update
apt install sysv-rc-conf
- 设置nginx开机启动：
先为nginx在下创建一个启动脚本/etc/init.d/
gedit /etc/init.d/nginx
添加内容如下：
#! /bin/sh
# chkconfig: 2345 55 25
# Description: Startup script for nginx webserver on Debian. Place in /etc/init.d and
# run 'update-rc.d -f nginx defaults', or use the appropriate command on your
# distro. For CentOS/Redhat run: 'chkconfig --add nginx'
### BEGIN INIT INFO
# Provides: nginx
# Required-Start: $all
# Required-Stop: $all# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: starts the nginx web server
# Description: starts nginx using start-stop-daemon
### END INIT INFO
# Author: licess
# website: http://lnmp.org
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
NAME=nginx
NGINX_BIN=/usr/local/nginx/sbin/$NAME
CONFIGFILE=/usr/local/nginx/conf/$NAME.conf
PIDFILE=/usr/local/nginx/logs/$NAME.pid
case "$1" in
start) echo -n "Starting $NAME... "
if netstat -tnpl | grep -q nginx;then
echo "$NAME (pid `pidof $NAME`) already running."
exit 1
fi
$NGINX_BIN -c $CONFIGFILE
if [ "$?" != 0 ] ; then
echo " failed"
exit 1 else
echo " done"
fi
;;
stop)
echo -n "Stoping $NAME... "
if ! netstat -tnpl | grep -q nginx; then
echo "$NAME is not running."
exit 1
fi
$NGINX_BIN -s stop
if [ "$?" != 0 ] ; then
echo " failed. Use force-quit"
exit 1
else
echo " done"
fi
;;
status)
if netstat -tnpl | grep -q nginx; then
PID=`pidof nginx`
echo "$NAME (pid $PID) is running..."
else
echo "$NAME is stopped"
exit 0 fi
;;
force-quit)
echo -n "Terminating $NAME... "
if ! netstat -tnpl | grep -q nginx; then
echo "$NAME is not running."
exit 1
fi
kill `pidof $NAME`
if [ "$?" != 0 ] ; then
echo " failed"
exit 1
else
echo " done"
fi
;;
restart)
$0 stop
sleep 1
$0 start
;;
reload) echo -n "Reload service $NAME... "
if netstat -tnpl | grep -q nginx; then
$NGINX_BIN -s reload
echo " done"
else
echo "$NAME is not running, can't reload."
exit 1
fi
;;
configtest)
echo -n "Test $NAME configure files... "
$NGINX_BIN -t
;;
*)
echo "Usage: $0 {start|stop|force-quit|restart|reload|status|configtest}"
exit 1
;;
esac
- 保存成功之后我们要对这个管理脚本设置一个权限：
chmod +x /etc/init.d/nginx
- 接下来我们可以看看这个脚本能否正确执行：
/etc/init.d/nginx restart
这个管理脚本支持的命令有start|stop|force-quit|restart|reload|status|configtest。
- 如果没有错误能正确执行，那我们可以开始把他加入启动项了：
sysv-rc-conf --list # 我们先查看一下list中有没有我们刚刚加进去的这个nginx管理脚本
sysv-rc-conf nginx on # 然后用这个命令添加开机自启动
二、运行Prometheus推流示例程序（Python编写）
运行如下命令：
roslaunch prometheus_detection web_cam0.launch # 打开一个usb摄像头0
roslaunch prometheus_detection rtmp_stream.launch # 开始推流
具体的Python推流代码如下（位置在）：
Prometheus/Modules/object_detection/py_nodes/rtmp_stream/ocv_rtmp_stream.py#!/usr/bin/env python
# -*- coding: utf-8 -*-
import rospy
from sensor_msgs.msg import Image
from geometry_msgs.msg import Pose, Point, Quaternion
from cv_bridge import CvBridge
from std_msgs.msg import String
from std_msgs.msg import Bool
import numpy as np
import cv2
import subprocess
import os
import yaml
import math
rospy.init_node('rtmp_stream', anonymous=True)
rtmp = r'rtmp://localhost:1935/live'
size_str = str(640) + 'x' + str(400)
command = ['ffmpeg', '-y', '-an', '-f', 'rawvideo', '-vcodec','rawvideo', '-pix_fmt', 'bgr24', '-s', size_str, '-r', '25', '-i', '-', '-c:v', 'libx264', '-pix_fmt', 'yuv420p', '-preset', 'ultrafast', '-f', 'flv', rtmp]
pipe = subprocess.Popen(
command,
shell=False,
stdin=subprocess.PIPE
)
def image_callback(imgmsg):
bridge = CvBridge()
frame = bridge.imgmsg_to_cv2(imgmsg, "bgr8")
# processing
# end
h, w = frame.shape[:2]
img_resize = 400
if h > w:
h = int(float(h) / w * img_resize)
w = img_resize
else:
w = int(float(w) / h * img_resize)
h = img_resize
frame = cv2.resize(frame, (w, h))
frame = frame[:, :640, :]
pipe.stdin.write(frame.tostring())
cv2.imshow("cap", frame)
# cv2.imshow("area", area)
cv2.waitKey(10)
def rtmp_stream(topic_name):
rospy.Subscriber(topic_name, Image, image_callback)
rospy.spin()
if __name__ == '__main__':
subscriber = rospy.get_param('~camera_topic', '/prometheus/camera/rgb/image_raw')
try:
rtmp_stream(subscriber)
except rospy.ROSInterruptException:
pass
pipe.terminate()
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