OpenCV从stdin加载图像/视频 [英] OpenCV load image/video from stdin
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问题描述
我正在尝试使用以下代码从stdin中读取jpg图像:
I am trying to read a jpg image from stdin using the following code:
int c,count=0;
vector<uchar> buffer; //buffer for coding
/* for stdin, we need to read in the entire stream until EOF */
while ((c = fgetc(stdin)) != EOF) {
buffer.push_back(c);
count++;
}
cout << "Bytes: " << count << endl;
Mat im = imdecode(Mat(buffer),CV_LOAD_IMAGE_COLOR);
cout << "Decoded\n";
namedWindow("image", CV_WINDOW_AUTOSIZE);
imshow("image",im);
cv::waitKey(0);
我在cmd中运行它:
OpenCVTest < thumb.jpg
这就是我得到的:
Bytes: 335
Decoded
OpenCV Error: Bad flag (parameter or structure field) (Unrecognized or unsupported array type) in unknown function, file ..\..\..\src\opencv\modules\core\src\array.cpp, line 2482
该错误似乎是合理的,因为该图像约为7 KB,但根据计数器,仅读取了335个字节.
The error seems reasonable since the image is about 7 KB and but according to the counter only 335 bytes have been read.
我在做什么错了?
我的最终目标是逐帧读取stdin中的视频.那有可能吗?
My ultimate goal is to read a video from stdin frame by frame. Would that be possible ?
非常感谢您!
推荐答案
以下内容从stdin逐帧读取jpeg序列.例子:
the following reads a jpeg sequence from stdin frame by frame. examples:
ffmpeg
ffmpeg -i input.mp4 -vcodec mjpeg -f image2pipe -pix_fmt yuvj420p -r 10 -|program.exe
mencoder
mencoder input.mp4 -nosound -ovc lavc -lavcopts vcodec=mjpeg -o -|program.exe
卷曲
curl "http://10.10.201.241/mjpeg/video.cgi&resolution=320x240"|program.exe
代码
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
using namespace cv;
#if defined(_MSC_VER) || defined(WIN32) || defined(_WIN32) || defined(__WIN32__) \
|| defined(WIN64) || defined(_WIN64) || defined(__WIN64__)
# include <io.h>
# include <fcntl.h>
# define SET_BINARY_MODE(handle) setmode(handle, O_BINARY)
#else
# define SET_BINARY_MODE(handle) ((void)0)
#endif
#define BUFSIZE 10240
int main ( int argc, char **argv )
{
SET_BINARY_MODE(fileno(stdin));
std::vector<char> data;
bool skip=true;
bool imgready=false;
bool ff=false;
int readbytes=-1;
while (1)
{
char ca[BUFSIZE];
uchar c;
if (readbytes!=0)
{
readbytes=read(fileno(stdin),ca,BUFSIZE);
for(int i=0;i<readbytes;i++)
{
c=ca[i];
if(ff && c==(uchar)0xd8)
{
skip=false;
data.push_back((uchar)0xff);
}
if(ff && c==0xd9)
{
imgready=true;
data.push_back((uchar)0xd9);
skip=true;
}
ff=c==0xff;
if(!skip)
{
data.push_back(c);
}
if(imgready)
{
if(data.size()!=0)
{
cv::Mat data_mat(data);
cv::Mat frame(imdecode(data_mat,1));
imshow("frame",frame);
waitKey(1);
}else
{
printf("warning");
}
imgready=false;
skip=true;
data.clear();
}
}
}
else
{
throw std::string("zero byte read");
}
}
}
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