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• Cannot get ffmpeg2.3.3 to work with Opencv2.4.9

  6 septembre 2014, par Siddharthan P R

  I need to open a video file in opencv2.4.9. I used the following code and I got the output : !!! Sorry cant find the video file !!!.

  So I figured I need to install ffmpeg first then install opencv. So I Uninstalled opencv and ffmpeg then tried to install ffmpeg 2.3.3 properly. Here are the methods i tried to install ffmpeg.

  Method 1: sudo apt-get install ffmpeg.

  Method 2: Download (HTTP): http://ffmpeg.org/releases/ffmpeg-2.3.3.tar.bz2

  Then i typed the following in the terminal after cd to the extracted folder.

  sed -i 's/-lflite"/-lflite -lasound"/' configure && 
  
  ./configure --prefix=/usr        \
              --enable-gpl         \
              --enable-version3    \
              --enable-nonfree     \
              --disable-static     \
              --enable-shared      \
              --disable-debug      \
              --enable-libass      \
              --enable-libfdk-aac  \
              --enable-libmp3lame  \
              --enable-libtheora   \
              --enable-libvorbis   \
              --enable-libvpx      \
              --enable-libx264     \
              --enable-x11grab     &&
  make &&
  gcc tools/qt-faststart.c -o tools/qt-faststart
  

  Though Method 1 works fine (in just installing ffmpeg), the problem with Method 1 is that i cannot use "./configure --enable-shared" anywhere because i cannot locate the file "configure".

  The problem with method 2 is that it says

  -ERROR: libass not found, after installing libass it says
  
  -ERROR: libfdk-aac-0.1.3 not found, then
  
  -ERROR: lame-3.8 not found, then
  
  -ERROR: libtheora not found, here i really got tired of installing all these packages. I stopped.
  

  I am really confused how to pull this off: with Method 1 or Method 2 (both seem not to work ). Can i change the ./ configure using method 1?

  Any help would be greatly appreciated.

              #include 
              #include 
  
              int main(int argc, char** argv) 
              {
                  cvNamedWindow("xample2", CV_WINDOW_AUTOSIZE);
                  CvCapture* capture = cvCreateFileCapture( "1.mp4" );
                  if (!capture)
                  {
                    std::cout << "!!! Sorry cant find the video file !!!\n";
                    return -1; 
                  }
  
                  IplImage* frame;
                  while (1) 
                  {
                      frame = cvQueryFrame(capture);
                      if(!frame) 
                          break;
  
                      cvShowImage("xample2", frame);
  
                      char c = cvWaitKey(33);
                      if (c == 27) 
                          break;
                  }
  
                  cvReleaseCapture(&capture);
                  cvDestroyWindow("xample2");
              }
  

• OpenCV cv2 not working in Windows 7

  6 septembre 2014, par Subhendu Sinha Chaudhuri

  I have a Windows 7 SP1 64 Bit machine with open cv2.4.9 installed and python 2.7.6 installed. I use pre compiled version of opencv

  The following code works perfectly for me

  import cv2.cv as cv
  import time
  
  cv.NamedWindow("camera", 0)
  
  capture = cv.CaptureFromCAM(0)
  
  while True:
      img = cv.QueryFrame(capture)
      cv.ShowImage("camera", img)
      if cv.WaitKey(10) == 27:
          break
  cv.DestroyAllWindows()
  

  Now when I try to use this code

  import cv2
  import numpy as np
  cam = cv2.VideoCapture(0)
  s, img = cam.read()
  
  winName = "Movement Indicator"
  cv2.namedWindow(winName, cv2.CV_WINDOW_AUTOSIZE)
  
  while s:
    cv2.imshow( winName,img )
  
    s, img = cam.read()
  
    key = cv2.waitKey(10)
    if key == 27:
      cv2.destroyWindow(winName)
      break
  
  print "Goodbye"
  

  The window is opened , the camera is initialized (as camera lights are on) , but nothing is displayed and the window closes and the program exits.

  WHERE am I going wrong??

  QUESTION 2 Can any one also suggest me how to capture live video stream from my Linux machine 192.168.1.3 . The stream is being generated by ffmpeg.

  The video stream can be opened in web browser. But I want to capture it with opencv and python.

• Save MJPEG video stream to a raw file

  6 septembre 2014, par user824963

  I've a cheap IP cam, and i need to save the video stream inside a single file.

  i've tried to execute the wget command towards the stream' url and the result was a file with this syntax:

  --object-ipcamera
  Content-Type:image/jpeg
  Content-Length:8012
  
  ÿØÿà [JPEG IMAGE CHARACTERS]  ÿÙ
  --object-ipcamera
  Content-Type:image/jpeg
  Content-Length:8012
  
  ÿØÿàÆÿ [JPEG IMAGE CHARACTERS]  ÿÿÿÙ
  --object-ipcamera
  Content-Type:image/jpeg
  Content-Length:8036
  

  Since i need to store the video stream, is mp4 a proper format to do that? What if mp4 file being truncated?

  I tried with ffmpeg:

  ffmpeg -i http://:99/vieostream.cgi out.mp4
  

  the output was

  [ingenient @ 0x1f51600] Could not find codec parameters for stream 0 (Video: mjpeg): unspecified size
  Consider increasing the value for the 'analyzeduration' and 'probesize' options
  [ingenient @ 0x1f51600] Estimating duration from bitrate, this may be inaccurate
  http://aaa@192.168.0.104:99/vieostream.cgi: could not find codec parameters
  

  and even setting these parameter to the max allowed value there is still the some output.

  I want also say that if i open the video url using VLC GUI, the video stream immediately comes out, so there is a way to auto-detect the video parameters?

  Note: my server has a small CPU

• GStreamer force decodebin2 output type

  6 septembre 2014, par user975326

  I'm trying to write a program in C which replicates the pipeline:

  gst-launch -v filesrc location="bbb.mp4" ! decodebin2 ! ffmpegcolorspace ! autovideosink
  

  DecodeBin2 has a dynamic pad and I've attached a callback to handle its creation. I am unable to link it to ffmpegcolorspace however because the pad capability is always video/quicktime. I would like it to be video/x-raw-yuv or something else which is compatible with ffmpegcolorspace.

  Is this possible to force/select the output type of decodebin2?

  Thanks.

  EDIT: Please do not recommend playbin. I'm trying to learn how how to make pipelines.

• ffmpeg silence detect and removal

  6 septembre 2014, par Zahlii

  I am trying to use the following command with the latest ffmpeg build to remove silence from my .mp3 files:

  ffmpeg -i SILENCE.mp3 -af silencedetect=n=-50dB:d=1 -y -ab 192k  SILENCE_OUT.mp3
  

  However, the following output is produced:

  ffmpeg version N-66154-g1654ca7 Copyright (c) 2000-2014 the FFmpeg developers
    built on Sep  5 2014 22:10:38 with gcc 4.8.3 (GCC)
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av
  isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab
  le-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --
  enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-lib
  modplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrw
  b --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinge
  r --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --en
  able-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis
   --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-
  libx265 --enable-libxavs --enable-libxvid --enable-decklink --enable-zlib
    libavutil      54.  7.100 / 54.  7.100
    libavcodec     56.  1.100 / 56.  1.100
    libavformat    56.  4.100 / 56.  4.100
    libavdevice    56.  0.100 / 56.  0.100
    libavfilter     5.  1.100 /  5.  1.100
    libswscale      3.  0.100 /  3.  0.100
    libswresample   1.  1.100 /  1.  1.100
    libpostproc    53.  0.100 / 53.  0.100
  Input #0, mp3, from 'SILENCE.mp3':
    Metadata:
      title           : Snowblind (Featuring Tasha Baxter)
      artist          : Au5
      album           : Snowblind (Featuring Tasha Baxter)
      genre           : Electronica
      performer       : Au5
      track           : 1/1
      date            : 2014
      album_artist    : Au5,Tasha Baxter
      major_brand     : mp42
      minor_version   : 0
      compatible_brands: isommp42
      encoder         : Lavf55.42.100
    Duration: 00:05:50.80, start: 0.025057, bitrate: 192 kb/s
      Stream #0:0: Audio: mp3, 44100 Hz, stereo, s16p, 192 kb/s
  Output #0, mp3, to 'SILENCE_OUT.mp3':
    Metadata:
      TIT2            : Snowblind (Featuring Tasha Baxter)
      TPE1            : Au5
      TALB            : Snowblind (Featuring Tasha Baxter)
      TCON            : Electronica
      TPE3            : Au5
      TRCK            : 1/1
      TDRL            : 2014
      TPE2            : Au5,Tasha Baxter
      major_brand     : mp42
      minor_version   : 0
      compatible_brands: isommp42
      TSSE            : Lavf56.4.100
      Stream #0:0: Audio: mp3 (libmp3lame), 44100 Hz, stereo, s16p, 192 kb/s
      Metadata:
        encoder         : Lavc56.1.100 libmp3lame
  Stream mapping:
    Stream #0:0 -> #0:0 (mp3 (native) -> mp3 (libmp3lame))
  Press [q] to stop, [?] for help
  [silencedetect @ 0000000004398f40] silence_start: -0.00628118
  [silencedetect @ 0000000004398f40] silence_end: 3.21413 | silence_duration: 3.22
  041
  [silencedetect @ 0000000004398f40] silence_start: 343.844
  [libmp3lame @ 00000000043b2940] Trying to remove 1152 samples, but the queue is
  empty
  size=    8223kB time=00:05:50.79 bitrate= 192.0kbits/s
  video:0kB audio:8222kB subtitle:0kB other streams:0kB global headers:0kB muxing
  overhead: 0.011485%
  

  The generated audio file however still has the original length without any silence removed. See the following images:

  Any help is appreciated!

  EDIT: Alright, silence detect is only DETECTING the silence. Not removing it. I will try to post a solution for this.