项目需求
python 客户端将opencv读取到的图片发送给python服务端，然后python服务端将opencv图发送给Linux设备，将处理结果通过C++ 传给服务端，然后服务端再传给客户端。
这里服务端可以改成C++ 写的，就不用这么麻烦了，但是需要将python的pickle包解码成C++ 的pickle包，还未尝试。
以下所给代码，并不一定能跑通，思路在哪里，结合自己的代码
第一步，python间通信
这种方式能一次性全部发送，一次性全部接受（如发一张图片，接受一张，发两张，接受两张）
方法一
Python Client
import datetime
import pickle
import time
import cv2
from multiprocessing.connection import Client
import os
host = 'localhost'
port = 9006
frame_num = 0
def connect_and_send(path, mode='file'):
global frame_num
client = Client((host, port))
while 1:
img_dict_list = []
# 从文件夹读取图片
if mode == 'file':
img_list = []
img_path = './data'
for filename in os.listdir(img_path):
read_img = cv2.imread(img_path + '/' + filename)
img_list.append(read_img)
# 存入dict
for i in range(len(img_list)):
img_obj = {'frame_num': i + 1, 'image': img_list[i],
'time': time.strftime('%Y%m%d%H%M%S', time.localtime())}
img_dict_list.append(img_obj)
else:
read_img = cv2.imread(path)
img_obj = {'frame_num': frame_num + 1, 'image': read_img,
'time': datetime.datetime.now().strftime('%M%S.%f')}
img_dict_list.append(img_obj)
frame_num += 1
# 1. obj to pickle 用json的话会慢，因为read_img需要to_list()
data_bytes = pickle.dumps(img_dict_list)
# 2. 发送文件
print('client send: ', datetime.datetime.now().strftime('%M%S.%f'))
client.send(data_bytes)
det_result = client.recv()
print('client receive: ', datetime.datetime.now().strftime('%M%S.%f'))
det_result = pickle.loads(det_result)
print(det_result)
break
if __name__ == '__main__':
connect_and_send('data/ship.jpg', mode='1')
Python Server端
import datetime
import pickle
import cv2
import numpy as np
from multiprocessing.connection import Listener
host = '192.168.0.2'
port = 9006
server_sock = Listener((host, port))
print("Connecting... ...")
sock = server_sock.accept()
while 1:
try:
received_bytes = sock.recv()
print('server receive: ', datetime.datetime.now().strftime('%M%S.%f'))
except Exception as e:
received_bytes = None
print(e)
if not received_bytes: # 当客户端下线，不让服务端下线
server_sock.close()
sock.close()
print("Client's data is empty !!!")
server_sock = Listener((host, port))
print("Reset Sever")
sock = server_sock.accept()
continue
else:
# bytes to list
img_dict_list = pickle.loads(received_bytes)
# detect
det_dict_list = []
img_num = len(img_dict_list)
img = img_dict_list[0]['image']
# img send to server
det_obj = {'frame_num': 1, 'det_output': getCResult(lib, det, img, img_num), # getCResult获取检测结果
'time': datetime.datetime.now().strftime('%Y%m%d%H%M%S.%f')}
det_dict_list.append(det_obj)
# send result to client
content = pickle.dumps(det_dict_list)
print('server send: ', datetime.datetime.now().strftime('%M%S.%f'))
sock.send(content)
参考链接：Python，用简单代码上传内存中的图片到远程服务器进行处理、Python传输图片（同一局域网下版本）
第二步，python调用C++ 动态库（opencv）返回检测结果
一共有cython、pybind11、ctypes等包，这里用的是ctypes
首先你需要有个.so文件，可以用cmake生成，注意python中你要调的包的位置，用camke不改.so文件的路径的话自动在当前文件夹生成，所以会报 **undefined symbol: strTest，**Linux指令：cp 复制文件
cmake自行查阅吧，这里做个示范
project(xxx)
add_library(xxx SHARED xxx.cpp) //这里会将.cpp中的非类方法加入到.so文件中
add_executable(yyy yyy.cpp)
target_link_libraries(yyy xxx)
link：https://www.cnblogs.com/blog-3123958139/p/5575360.html
难点一：传输字符串 string to std::string
C++ 端：
extern "C" { // 加了才能识别到括号内的方法，必须！用C格式写代码
int Detect_Init(Detect* det, char* config_path){ // det用于调用类方法，后续会讲
std:string config_path1(config_path, sizeof(config_path)); // 将char*转为string类型
return det->Init(config_path1);
}
}
python端
from ctypes import *
import ctypes
ll = ctypes.cdll.LoadLibrary
lib = ll("../lib/libDetect.so")
# 设置传递参数类型argtypes和返回类型restype
lib.Detect_new.argtypes = []
lib.Detect_new.restype = ctypes.c_void_p
lib.Detect_Init.argtypes = [ctypes.c_void_p, ctypes.c_char_p, ctypes.c_int]
lib.Detect_Init.restype = ctypes.c_int
# 创建一个Detect对象，后续会讲
det = lib.Detect_new()
# init
# 注意将string.encode()不行，编码到.就结束了
config = bytes("../../weights/DetectConfig.yaml", encoding='utf-8') # 字符串任意，注意路径
# 如果需要传递可修改字符串，参考：https://zhuanlan.zhihu.com/p/215790047
# 使用create_string_buffer("test".encode('utf-8'))
lib.Detect_Init(det, config)
参考链接：Python调用C的基础学习（传递数字、字符串、数组（一维、二维）、结构体）
难点二：调用C++ 类方法
C++ 端
class Foo{ //此处不贴自己的代码了，粘贴参考链接的代码
public:
Foo(int);
void bar();
int foobar(int);
private:
int val;
};
Foo::Foo(int n) {val = nl;}
void Foo::bar() {
std::cout << "Value is " << val << std::endl;
}
int Foo::foobar(int n) {return val + n;}
extern "C"{ //用于python调用
Foo* Foo_new(int n) {return new Foo(n);} //核心点，创建一个调用类方法的对象
void Foo_bar(Foo* foo) {foo->bar();}
int Foo_foobar(Foo* foo, int n) {return foo->foobar(n);}
}
python端
import ctypes
lib = ctypes.cdll.LoadLibrary('./libfoo.so') # 注意路径
class Foo(object): # 也可以不写类，直接放在一个def里
def __init__(self, val):
lib.Foo_new.argtypes = [ctypes.c_int]
lib.Foo_new.restype = ctypes.c_void_p
lib.Foo_bar.argtypes = [ctypes.c_void_p]
lib.Foo_bar.restype = ctypes.c_void_p
lib.Foo_foobar.argtypes = [ctypes.c_void_p, ctypes.c_int]
lib.Foo_foobar.restype = ctypes.c_int
self.obj = lib.Foo_new(val)
def bar(self):
lib.Foo_bar(self.obj)
def foobar(self, val):
return lib.Foo_foobar(self.obj, val)
f=Foo(5)
# Calling f.bar() will print a message including the value...
f.bar()
# Now we'll use foobar to add a value to that stored in our Foo object, f
print (f.foobar(7))
# Now we'll do the same thing - but this time demonstrate that it's a normal
# Python integer...
x = f.foobar(2)
print (type(x))
参考链接：Calling C++ Classes from Python, with ctypes…、python 调用 C++ dll, 包含类以及opencv Mat、
难点三：传输结构体并带Mat图片
此处一个坑点是C++ 结构体的变量顺序和变量类型必须与python的类一致！！！！一定要仔细校对
C++ 类型和Python类型对照网址
二维数据在python里需要倒着写 C++ [20][5],python [5][20]
C++ 端
extern "C" {
typedef struct
{
int image_num;
int width[32];
int height[32];
char* frame[32]; // 注意是char* 网上不是uchar*就是POINTER(ubyte) 实际上char*也可，为了与python对应
}PythonImage;
void getInfo(PythonImage input){ //验证是否传输成功
printf("-----Information------\n");
printf("width: %d, height: %d\n", input.width[0], input.height[0]);
}
DetectOutput Detect_Run(Detect* det, PythonImage img){ // DetectOutput是嵌套结构体，只要细心一般都能返回
cv::Mat frame(img.height[0], img.width[0], CV_8UC3, img.frame[0]); // 将char* 转为 Mat格式
return det->Run(frame); //将图片发给检测算法
}
}
python端
from ctypes import *
import ctypes
class PythonImage(Structure):
_fields_ = [('image_num', c_int), # 注意 _fields_ 是双下划线
('width', c_int * val), # val=32
('height', c_int * val),
('frame', c_char_p * val)] # 与C++ 保持一致
ll = ctypes.cdll.LoadLibrary
lib = ll("../lib/libDetect.so")
lib.Detect_Run.argtypes = [ctypes.c_void_p, PythonImage] # 注意此处填class名而不是Structure
lib.Detect_Run.restype = DetectOutput
det = lib.Detect_new()
pi = PythonImage()
PARAM = c_int * 32
height = PARAM()
height[0] = frame.shape[0]
pi.height = height
width = PARAM()
width[0] = frame.shape[1]
pi.width = width
# 对cv2图片进行处理
frame_data = np.asarray(frame, dtype=np.uint8)
frame_data = frame_data.ctypes.data_as(c_char_p)
pi.frame[0] = frame_data
pi.image_num = image_num # 传输图片的数量
lib.getInfo.argtypes = [PythonImage]
lib.getInfo(pi)
lib.Detect_Run(det, pi) # 检测结果
小难点1：嵌套结构体传输/读取指针值/ctypes BUG？
注意C++ 结构体的变量顺序和变量类型必须与python的类一致！！！！一定要仔细校对，其他应该没有什么问题
C++ 端
typedef enum AttributeType
{
PERSON_HEAD = 0,
PERSON_NECK,
} AttributeType;
typedef struct cv_box
{
float x;
float y;
float w;
float h;
} cv_box;
typedef struct cv_object
{
cv_box bbox;
int classes;
float *prob;
AttributeType attribute;
int a[7];
} cv_object;
typedef struct cv_object_list
{
cv_object object[128];
int object_num; // 注意这里的顺序 必须object_num 在object[128] 上面， ！！！bug
// 即两行互换位置，否则无法读取object_num的值，具体为什么不清楚
int test[7];
}cv_object_list;
python端
class cv_box(Structure):
_fields_ = [('x', c_float),
('y', c_float),
('w', c_float),
('h', c_float)]
class cv_object(Structure):
_fields_ = [('bbox', cv_box),
('classes', c_int),
('prob', POINTER(c_float)),
('attribute', c_int), # 枚举类型是c_int
('a', c_int * 7)]
class cv_object_list(Structure):
_fields_ = [('object', cv_object * 128),
('object_num', c_int),
('test', c_int * 7)]
# 输出指针值
prob = POINTER(c_float)(object[0].prob) # 即float* prob
print(prob.contents.value) # 获取到c_float()中括号内的值
参考链接：https://blog.csdn.net/Kelvin_Yan/article/details/86546784#t2
小难点2：python获取C++ .h文件内容
参考链接：Python解析C++ 头文件
import CppHeaderParser
cppHeader = CppHeaderParser.CppHeader("../include/type.h")
val = 32
OBJECT_NUM = 128
for h in cppHeader.defines:
if 'BATCH_SIZE' in h:
val = int(h.split(' ')[-1])
if 'OBJECT_NUM' in h:
OBJECT_NUM = int(h.split(' ')[-1])
第三步 传输视频
参考博客：opencv cv2.imshow显示图片一片黑色、 python:读取视频，处理后，实时计算帧数fps、opencv imencode跟imdecode函数jpg（python）
首先如果转换m4s格式到mp4格式，使用命令：ffmpeg -i all.m4s -c copy video.mp4
这个比较简单，总体思路就是opencv读取视频，按帧发送，然后接受回传结果并绘制
客户端
def send_data(img_dict):
start = int(round(time.time() * 1000))
start_time = time.strftime("%Y-%m-%d %H:%M:%S", time.localtime())
# 1. send data
data_bytes = pickle.dumps(img_dict)
client.send(data_bytes) # 貌似client是全局变量
# 2. receive data
det_result = client.recv()
det_result = pickle.loads(det_result)
# print(det_result)
# cal time cost
end = int(round(time.time() * 1000))
end_time = time.strftime("%Y-%m-%d %H:%M:%S", time.localtime())
time_cost = end - start
print('client total time cost: ', time_cost)
# 3. draw boxes 自己写
draw_box(det_result, img_dict)
# 4. save logs 自己写
det_frame_num = det_result['frame_num']
save_logs(time_cost, start_time, end_time, det_frame_num)
def image_send(img):
global frame_num
img_param = [cv2.IMWRITE_JPEG_QUALITY， 95] # 压缩率
_, img = cv2.imencode('.jpg', img, img_param)
# 为了统一图片，如果单要视频，可以直接传输图片img
img_obj = {'frame_num': frame_num, 'image': img}
frame_num += 1
send_data(img_obj)
def read_video_send(path):
global frame_num
frame_num = 1 # 重置frame_num 使其适配视频第一帧
video = cv2.VideoCapture(path)
while True:
_, img = video.read()
cv2.imshow('client', img)
cv2.waitKey(1) # 不加就黑屏
start = time.time()
image_send(img) # send img
end = time.time()
seconds = end - start
fps = 1 / seconds
print("Estimated FPS: {0}".format(fps))
if __name__ == '__main__':
img_file = './data'
img_pa = './data/1.jpg'
client = Client((host, port))
mode = 'video'
if mode == 'image':
read_img = cv2.imread(img_pa)
image_send(read_img)
elif mode == 'images':
read_images_send(img_file)
elif mode == 'video':
read_video_send('./video/1.mp4')
服务端
def connect_send(host, port, lib, det):
server_sock = Listener((host, port))
print("Connecting... ...")
sock = server_sock.accept()
while 1:
try:
received_bytes = sock.recv()
except Exception as e:
received_bytes = None
print(e)
if received_bytes is None: # 不能是not received，否则传视频有问题
server_sock.close()
sock.close()
print("Client's data is empty !!!")
server_sock = Listener((host, port))
print("Reset Sever")
sock = server_sock.accept()
continue
else:
# bytes to list to cv
img_dict = pickle.loads(received_bytes)
img_dict['image'] = cv2.imdecode(img_dict['image'], cv2.IMREAD_COLOR)
# detect one image
det_dict = detect_img(img_dict, lib, det, 1)
# send result to client
content = pickle.dumps(det_dict)
sock.send(content)
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