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• How to solve error : "cvCreateFileCaptureWithPreference : backend FFMPEG doesn't support legacy API anymore"

  24 octobre 2018, par Sarvin

  I am trying to build and run an OpenCV project from Github using OpenCV 3.4.2, Cmake 3.13.0-rc1 and VS 2017. The project builds successfully as I understand from the build output but it throws the above warning after I run the program. The video I want to load is in a .AVI format and uses cvCaptureFromAVI function. Just trying to learn OpenCV, your help and kindness is appreciated.

  Source :

  #include <iostream>
  
  #include <opencv2></opencv2>opencv.hpp>
  
  
  
  #include "package_bgs/PBAS/PixelBasedAdaptiveSegmenter.h"
  
  #include "package_tracking/BlobTracking.h"
  
  #include "package_analysis/VehicleCouting.h"
  
  
  
  using namespace cv;
  
  
  
  int main(int argc, char **argv)
  
  {
  
    std::cout &lt;&lt; "Using OpenCV " &lt;&lt; CV_MAJOR_VERSION &lt;&lt; "." &lt;&lt; 
  
    CV_MINOR_VERSION &lt;&lt; "." &lt;&lt; CV_SUBMINOR_VERSION &lt;&lt; std::endl;
  
  
  
    /* Open video file */
  
    CvCapture *capture = 0;
  
  
  
    capture = cvCaptureFromAVI("video.avi");
  
    if(!capture){
  
      std::cerr &lt;&lt; "Cannot open video ting tong!" &lt;&lt; std::endl;
  
      return 1;
  
    }
  
  
  
    /* Background Subtraction Algorithm */
  
    IBGS *bgs;
  
    bgs = new PixelBasedAdaptiveSegmenter;
  
  
  
    /* Blob Tracking Algorithm */
  
  
  
  
  
  
  
  cv::Mat img_blob;
  
    BlobTracking* blobTracking;
  
    blobTracking = new BlobTracking;
  
  
  
    /* Vehicle Counting Algorithm */
  
    VehicleCouting* vehicleCouting;
  
    vehicleCouting = new VehicleCouting;
  
  
  
    std::cout &lt;&lt; "Press 'q' to quit..." &lt;&lt; std::endl;
  
    int key = 0;
  
    IplImage *frame;
  
    while(key != 'q')
  
    {
  
      frame = cvQueryFrame(capture);
  
      if(!frame) break;
  
  
  
      cv::Mat img_input = cv::cvarrToMat(frame);
  
      cv::imshow("Input", img_input);
  
  
  
      // bgs->process(...) internally process and show the foreground mask image
  
      cv::Mat img_mask;
  
      bgs->process(img_input, img_mask);
  
  
  
      if(!img_mask.empty())
  
      {
  
        // Perform blob tracking
  
        blobTracking->process(img_input, img_mask, img_blob);
  
  
  
        // Perform vehicle counting
  
        vehicleCouting->setInput(img_blob);
  
        vehicleCouting->setTracks(blobTracking->getTracks());
  
        vehicleCouting->process();
  
      }
  
  
  
      key = cvWaitKey(1);
  
    }
  
  
  
    delete vehicleCouting;
  
    delete blobTracking;
  
    delete bgs;
  
  
  
    cvDestroyAllWindows();
  
    cvReleaseCapture(&amp;capture);
  
  
  
    return 0;
  
  }
  
  </iostream>

  Error :

  

• Live stream is gets delayed while processing frame in opencv + python

  18 mars 2021, par Himanshu sharma

  I capture and process an IP camera RTSP stream in a OpenCV 4.4.0.46 on Ubuntu.
Unfortunately the processing takes quite a lot of time, roughly 0.2s per frame, and the stream quickly gets delayed.
Video file have to save for 5 min but by this delaying video file is saved for 3-4 min only.

  


  Can we process faster to overcome delays ?

  


  I have two IP camera which have two diffrent fps_rate(Camera 1 have 18000 and camera 2 have 20 fps)

  


  I am implementing this code in difference Ubuntu PCs

  


  

  • Python 3.8.5 (default, Jul 28 2020, 12:59:40) [GCC 9.3.0] on linux

  


  • Django==3.1.2

  


  • Ubuntu = 18.04 and 20.04

  


  • opencv-contrib-python==4.4.0.46

  


  • opencv-python==4.4.0.46

  


  


  input_stream = 'rtsp://'+username+':'+password+'@'+ip+'/user='+username+'_password='+password+'_channel=0channel_number_stream=0.sdp'
input_stream---> rtsp://admin:Admin123@192.168.1.208/user=admin_password=Admin123_channel=0channel_number_stream=0.sdp

input_stream---> rtsp://Admin:@192.168.1.209/user=Admin_password=_channel=0channel_number_stream=0.sdp

vs = cv2.VideoCapture(input_stream)
fps_rate = int(vs.get(cv2.CAP_PROP_FPS))
I have two IP camera which have two diffrent fps_rate(Camera 1 have 18000 and camera 2 have 20 fps)

video_file_name = 0
start_time = time.time()
while(True):
    ret, frame = vs.read()
    time.sleep(0.2)     # <= Simulate processing time (mask detection, face detection and many detection is hapning)


    ###  Start of  writing a video to disk          
    minute = 5  ## saving a file for 5 minute only then saving another file for 5 min
    second  = 60
    minite_to_save_video = int(minute) * int(second)


    # if we are supposed to be writing a video to disk, initialize
    if time.time() - start_time >= minite_to_save_video or  video_file_name == 0 :
        ## where H = heigth, W = width, C = channel 
        H, W, C = frame.shape
        
        print('time.time()-->',time.time(),'video_file_name-->', video_file_name,  ' #####')
        start_time = time.time()

        video_file_name = str(time.mktime(datetime.datetime.now().timetuple())).replace('.0', '')
        output_save_directory = output_stream+str(int(video_file_name))+'.mp4'


        fourcc = cv2.VideoWriter_fourcc(*'avc1')
        
        writer = cv2.VideoWriter(output_save_directory, fourcc,20.0,(W, H), True)

    # check to see if we should write the frame to disk
    if writer is not None:
        
        try:
            writer.write(frame)

        except Exception as e:
            print('Error in writing video output---> ', e)


  


• FFPROBE get start-time of audio only

  13 février 2023, par Marcus

  I am using this to get the start time of the video and audio :

  


  ffprobe -show_entries stream=start_time -i https://www.website.com/video.mp4


  


  And the response I get is :

  


      ffprobe version 4.3.1 Copyright (c) 2007-2020 the FFmpeg developers
      built with Apple clang version 12.0.0 (clang-1200.0.32.28)
      configuration: --prefix=/usr/local/Cellar/ffmpeg/4.3.1_9 --enable-shared --enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr --enable-videotoolbox --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack
      libavutil      56. 51.100 / 56. 51.100
      libavcodec     58. 91.100 / 58. 91.100
      libavformat    58. 45.100 / 58. 45.100
      libavdevice    58. 10.100 / 58. 10.100
      libavfilter     7. 85.100 /  7. 85.100
      libavresample   4.  0.  0 /  4.  0.  0
      libswscale      5.  7.100 /  5.  7.100
      libswresample   3.  7.100 /  3.  7.100
      libpostproc    55.  7.100 / 55.  7.100
    Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'https://www.website.com/video.mp4':
      Metadata:
        major_brand     : isom
        minor_version   : 512
        compatible_brands: isomiso2avc1mp41
        encoder         : Lavf58.76.100
      Duration: 00:03:14.85, start: 0.000000, bitrate: 4488 kb/s
        Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 4418 kb/s, 24 fps, 24 tbr, 90k tbn, 48 tbc (default)
        Metadata:
          handler_name    : VideoHandler
        Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 69 kb/s (default)
        Metadata:
          handler_name    : SoundHandler
[STREAM]
start_time=0.000000
[/STREAM]
[STREAM]
start_time=9.892993
[/STREAM]


  


  How can I get only the second stream, which is the audio, and without all the extra info ?

  


  So the response would just be :

  


  


  start_time=9.892993