opencv imencode 出现断言

Question

// 获取视频文件  
VideoCapture cap(1);
if (!cap.isOpened())
{
    AfxMessageBox("打开摄像头失败！！！");
}
// 获取视频总帧数  
long totalFrameNumber = cap.get(CV_CAP_PROP_FRAME_COUNT);

Mat frame;
cap.read(frame);
Framemem = sizeof(frame);
vector<unsigned char> inImage;
imencode(".jpg", frame, inImage);
size_t datalen = inImage.size();
char *msgImage = new char[datalen];
for (int i = 0; i<datalen; i++)
{
    msgImage[i] = inImage[i];
}
总是在imencode 出现断言，0x01E30A14 (opencv_world300.dll) (controller.exe 中)处有未经处理的异常:  0xC0000005:  读取位置 0x0CE5B000 时发生访问冲突。
求解决

Answer 1

Configuring Nginx
We want to allow users to download files at the following location: "/files/file_name/". file_name represents the file to download.

We start from a classic nginx proxy configuration proxying requests to our web application.

upstream proxy_app {
server 127.0.0.1:7000;
}

server {
listen 80;
server_name example.com;

rewrite_log on;
access_log      /var/log/nginx/access.log;
error_log       /var/log/nginx/error.log debug;

client_max_body_size 4G;
keepalive_timeout 5;

root /var/www;

location / {
    # checks for static file, if not found proxy to app
    try_files $uri/index.html $uri.html $uri @forward_to_app;
}

location @forward_to_app {
    include /etc/nginx/proxy_params;
    proxy_pass      http://proxy_app;
}

}

The idea here is to add an internal directive to URLs for private files and a couple proxy headers.

$ diff -u prev /etc/nginx/conf.d/default
...

• location /files/(.*)/ {
• internal;
• alias /path/to/your/private/files/$1/;

• }

  location @forward_to_app {
  include /etc/nginx/proxy_params;
  proxy_pass http://proxy_app;

•   proxy_set_header X-Sendfile-Type   X-Accel-Redirect;
  

•   proxy_set_header X-Accel-Mapping   /path/to/your/private/files/=/files/(.*)/;
  

  ...

Configuring the Web application
Django
We were serving PDF files through Django here. To have the files served by nginx instead, we return an HttpResponse with an empty body and add a X-Accel-Redirect header. For example:

...
response = HttpResponse()
response['Content-Type'] = 'application/pdf'
response['Content-Disposition'] = 'attachment; filename=%s.pdf' % (file_name, )
response['X-Accel-Redirect'] = '/files/%s' % (file_name, )
return response

Rails
Working with Rails is about the same though a bit different. All the magic happens in the Rack::sendfile middleware. We only need to configure the appropriate x_sendfile_header then call send_file as usual.

In config/environments/production.rb:

# Set header to use.
config.action_dispatch.x_sendfile_header = 'X-Accel-Redirect'

In the controller:

# In case of PDF file
send_file(
    path,
    :disposition => 'inline',
    :type => "application/pdf")