I want to receive JPEG images from an IP camera (over RTSP). For this, I tried cvCreateFileCapture_FFMPEG
in OpenCV. But ffmpeg seems to have some problem with the MJPEG format of the streaming (since it automatically tries to detect the streaming info) and I end up with the following error
mjpeg: unsupported coding type
I, then, decided to use live555 for streaming. Till now, I can successfully establish streaming and capture (non-decoded) images through openRTSP.
The question is how can I do this in my application, e.g., in OpenCV. How can I use openRTSP in OpenCV to get images and save them in JPEG format?
I have heard that the data from openRTSP can be sent to a buffer (or a named pipe) and then read in OpenCV's IplImage
. But I don't know how to do this.
I will really appreciate any help/suggestion in about this problem. I need answers of either of the following questions:
Regards,
Is this an Axis IP camera? Either way, most IP cameras that provide MPEG4 RTSP stream that can be decoded using OpenCV using cvCreateFileCapture_FFMPEG. However, ffmpeg decoder's MJPEG codec has a widely known unresolved issues. I am sure you would have received an error similar to
[ingenient @ 0x97d20c0]Could not find codec parameters (Video: mjpeg)
Option1 : Using opencv, libcurl and libjpeg
To view mjpeg stream in opencv take a look at the following implementation
http://www.eecs.ucf.edu/~rpatrick/code/onelinksys.c or http://cse.unl.edu/~rpatrick/code/onelinksys.c
Option2: Using gstreamer (no opencv)
I would recommend looking at gstreamer if your goal is to just view or save jpeg images
To view MJPEG stream one may execute media pipeline string as follows
gst-launch -v souphttpsrc location="http://[ip]:[port]/[dir]/xxx.cgi" do-timestamp=true is_live=true ! multipartdemux ! jpegdec ! ffmpegcolorspace ! autovideosink
For RTSP
gst-launch -v rtspsrc location="rtsp://[user]:[pass]@[ip]:[port]/[dir]/xxx.amp" debug=1 ! rtpmp4vdepay ! mpeg4videoparse ! ffdec_mpeg4 ! ffmpegcolorspace! autovideosink
To work with C API see
http://wiki.maemo.org/Documentation/Maemo_5_Developer_Guide/Using_Multimedia_Components/Camera_API_Usage
For a simple example take a look at my other post on rtsp for constructing gstreamer C API media pipeline (This is same as gst-launch string but rather implemented as a C API)
Playing RTSP with python-gstreamer
To save MJPEG stream as multiple images the pipeline (Let us put a vertical flip BIN and connect the PADS to the previous and the next BINS to make it fancier)
gst-launch souphttpsrc location="http://[ip]:[port]/[dir]/xxx.cgi" do-timestamp=true is_live=true ! multipartdemux ! jpegdec ! videoflip method=vertical-flip ! jpegenc ! multifilesink location=image-out-%05d.jpg
Also maybe worthwhile have a look at gst-opencv
UPDATE:
Option3: Using gstreamer, Named Pipe and opencv
On Linux one may get mjpeg stream and convert it to mpeg4 and feed it to a named pipe. Then read the data from the named pipe in opencv
Step 1. Create Named Pipe
mkfifo stream_fifo
Step 2. Create opencvvideo_test.c
// compile with gcc -ggdb `pkg-config --cflags --libs opencv` opencvvideo_test.c -o opencvvideo_test
#include <stdio.h>
#include "highgui.h"
#include "cv.h"
int main( int argc, char** argv){
IplImage *frame;
int key;
/* supply the AVI file to play */
assert( argc == 2 );
/* load the AVI file */
CvCapture *capture = cvCreateFileCapture(argv[1]) ;//cvCaptureFromAVI( argv[1] );
/* always check */
if( !capture ) return 1;
/* get fps, needed to set the delay */
int fps = ( int )cvGetCaptureProperty( capture, CV_CAP_PROP_FPS );
int frameH = (int) cvGetCaptureProperty(capture, CV_CAP_PROP_FRAME_HEIGHT);
int frameW = (int) cvGetCaptureProperty(capture, CV_CAP_PROP_FRAME_WIDTH);
/* display video */
cvNamedWindow( "video", CV_WINDOW_AUTOSIZE );
while( key != 'q' ) {
double t1=(double)cvGetTickCount();
/* get a frame */
frame = cvQueryFrame( capture );
double t2=(double)cvGetTickCount();
printf("time: %gms fps: %.2g\n",(t2-t1)/(cvGetTickFrequency()*1000.), 1000./((t2-t1)/(cvGetTickFrequency()*1000.)));
/* always check */
if( !frame ) break;
/* display frame */
cvShowImage( "video", frame );
/* quit if user press 'q' */
key = cvWaitKey( 1000 / fps );
}
/* free memory */
cvReleaseCapture( &capture );
cvDestroyWindow( "video" );
return 0;
}
Step 3. Prepare To Convert From MJPEG to MPEG4 using gstreamer (rate of incoming frames critical)
gst-launch -v souphttpsrc location="http://<ip>/cgi_bin/<mjpeg>.cgi" do-timestamp=true is_live=true ! multipartdemux ! jpegdec ! queue ! videoscale ! 'video/x-raw-yuv, width=640, height=480'! queue ! videorate ! 'video/x-raw-yuv,framerate=30/1' ! queue ! ffmpegcolorspace ! 'video/x-raw-yuv,format=(fourcc)I420' ! ffenc_mpeg4 ! queue ! filesink location=stream_fifo
Step 4. Display Stream in OpenCV
./opencvvideo_test stream_fifo
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With