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• I can't seem to install opencv2.4.13 for Python3.4 on Mac El Capitan

  1er juin 2016, par ThatProgrammerDude

  This has been driving me nuts. I have been working on this non stop for a week. I have looked at many tutorials online they did not help.

  I have tried so much I don’t even remember what I tried. I can say the last thing I tried though.. which is this video https://www.youtube.com/watch?v=U49CVY8yOxw.

  So I download opencv2.4.13, create the build folder, open cmake, configure, generate and then go to terminal and type in make.

  I get this :

  Richie's Macbook Air:build Richie$ make
  
  [  2%] Built target zlib
  
  [  6%] Built target libtiff
  
  [ 10%] Built target libjpeg
  
  [ 14%] Built target libjasper
  
  [ 16%] Built target libpng
  
  [ 23%] Built target IlmImf
  
  [ 26%] Built target opencv_core
  
  [ 31%] Built target opencv_imgproc
  
  [ 32%] Built target opencv_video
  
  [ 32%] Built target opencv_flann
  
  [ 32%] Building CXX object modules/highgui/CMakeFiles/opencv_highgui.dir/src/cap_ffmpeg.cpp.o
  
  In file included from /Users/Richie/Downloads/opencv-2.4.13/modules/highgui/src/cap_ffmpeg.cpp:45:
  
  /Users/Richie/Downloads/opencv-2.4.13/modules/highgui/src/cap_ffmpeg_impl.hpp:71:6: error: 
  
        "libswscale is necessary to build the newer OpenCV ffmpeg wrapper"
  
      #error "libswscale is necessary to build the newer OpenCV ffmpeg wrapper"
  
       ^
  
  /Users/Richie/Downloads/opencv-2.4.13/modules/highgui/src/cap_ffmpeg_impl.hpp:481:9: error: 
  
        use of undeclared identifier 'sws_freeContext'
  
          sws_freeContext(img_convert_ctx);
  
          ^
  
  /Users/Richie/Downloads/opencv-2.4.13/modules/highgui/src/cap_ffmpeg_impl.hpp:965:17: error: 
  
        use of undeclared identifier 'SWS_BICUBIC'
  
                  SWS_BICUBIC,
  
                  ^
  
  /Users/Richie/Downloads/opencv-2.4.13/modules/highgui/src/cap_ffmpeg_impl.hpp:998:5: error: 
  
        use of undeclared identifier 'sws_scale'
  
      sws_scale(
  
      ^
  
  /Users/Richie/Downloads/opencv-2.4.13/modules/highgui/src/cap_ffmpeg_impl.hpp:1639:46: error: 
  
        use of undeclared identifier 'SWS_BICUBIC'
  
                                               SWS_BICUBIC,
  
                                               ^
  
  /Users/Richie/Downloads/opencv-2.4.13/modules/highgui/src/cap_ffmpeg_impl.hpp:1645:14: error: 
  
        use of undeclared identifier 'sws_scale'
  
          if ( sws_scale(img_convert_ctx, input_picture->data,
  
               ^
  
  /Users/Richie/Downloads/opencv-2.4.13/modules/highgui/src/cap_ffmpeg_impl.hpp:1693:9: error: 
  
        use of undeclared identifier 'sws_freeContext'
  
          sws_freeContext(img_convert_ctx);
  
          ^
  
  /Users/Richie/Downloads/opencv-2.4.13/modules/highgui/src/cap_ffmpeg_impl.hpp:2290:9: warning: 
  
        ignoring return value of function declared with warn_unused_result
  
        attribute [-Wunused-result]
  
          avformat_write_header(oc_, NULL);
  
          ^~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~
  
  1 warning and 7 errors generated.
  
  make[2]: *** [modules/highgui/CMakeFiles/opencv_highgui.dir/src/cap_ffmpeg.cpp.o] Error 1
  
  make[1]: *** [modules/highgui/CMakeFiles/opencv_highgui.dir/all] Error 2
  
  make: *** [all] Error 2
  
  Richie's Macbook Air:build Richie$ 

  From what I can see, it says

  "libswscale is necessary to build the newer OpenCV ffmpeg wrapper"

  I have tried googling though to no avail, does anyone know ?

  EDIT : I do have ffmpeg installed... (brew).

• how can i insert an empty subtitle

  22 avril 2020, par Ginso

  i have a bunch of mp4 files and i would like to convert them to mkv, so that the automatic selection auf audio and subtitle track of vlc works.
the thing is some of them have 4 subtitles (first german and english only for foreign languages and then german and english for all) and some of them only 2 (because in those episodes there are no foreign languages). Can i insert 2 empty subtitle tracks before them so that i can set my vlc to select the first or second subtitle when i watch them ?

  



  i convert the episodes with 4 subtitles like this :

  



  ffmpeg -i in.mp4 -map 0:0 -map 0:1 -map 0:2 -map 0:3 -map 0:4 -map 0:5 -map 0:6 out.mkv

  



  0:0 is of course the video

  



  0:1 and 0:2 are audio tracks

  



  the rest are the subtitles

  



  BTW : is there a language code for forced subtitles ? -metadata:s:s:1 language=?

  


• php streaming video : can tmp file be accessed before move_uploaded_file ?

  5 août 2019, par Jintor

  My question is about accessing file while they are being uploaded to the server.

  Can I perform "live" video streaming but BEFORE move_uploaded_file ???

  because move_uploaded_file have to wait until the video is completely finished.

  <?php
  
  // Can I access tmp before move_uploaded_file ?
  
  move_uploaded_file('tmp_name','new_location');

  Is there a way to access the tmp file during upload and perform ffmpeg ?

  I was considering upload by chunk via xhr request... but it seems .mp4 from a mobile don’t necessarily apply a fast start...

  how live streaming services companies do it ?

  ---

  **** More clarifications :
  Live streaming. Example User X take his phone and want to go live, he hit a button "stream yourself" than the camera starts recording and while uploading, the server begins to save it to the server and other users like Y, Z, A, B begin to watch while X is still begin live