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• How to Crop Video in Kotlin Similar to Image Cropping Using FFmpeg ? [closed]

  19 septembre 2024, par Hafsa Azram

  I'm currently working on a Kotlin application where I need to crop videos in a manner similar to how images are cropped (i.e., selecting a rectangular area of the video to keep, rather than just trimming time segments). I'm using FFmpeg for video processing, but I'm encountering issues with the cropping commands.

  


  If FFmpeg is not suitable for video cropping, what other libraries or tools are available for this purpose in Kotlin ? How can I integrate and use these libraries in my project for cropping videos ?

  


• FFMPEG API and cropping

  24 juin 2016, par Jguillot

  I learned how to use FFMPEG API with dranger’s tutorial, and I implemented a video reader using the library SDL to display the video.

  I have a HD video 1280*720 (i only worked with mp4) and i want to select a VGA-screen anywhere in the HD video (I mean cropping a VGA screen in a HD video), recuperate the data and display it on screen.

  In the FFMPEG API, we can use the function av_picture_crop (here). I get a "yellow" overlay on the cropped video and my application crashes after fews seconds. Before posting here, i read here that the function wasn’t finish yet. But when i reading the code, i don’t find a way to finish it.
  This is a part of my code :

  AVFrame *pFrame = NULL;
  
  AVFrame *pFrameCropped = NULL;
  
  bmp = SDL_CreateYUVOverlay(CODEC_WIDTH, // width
  
                            CODEC_HEIGHT, // height
  
                            SDL_YV12_OVERLAY, // format
  
                            screen); // SDL_Surface to display
  
  
  
  
  
  sws_ctx = sws_getContext(CODEC_WIDTH, // src width
  
                          CODEC_HEIGHT, // src height
  
                          pCodecCtx->pix_fmt, // src img format
  
                          STREAM_WIDTH, // dest width, 
  
                          STREAM_HEIGHT, // dest height
  
                          AV_PIX_FMT_YUV420P, // dest img format
  
                          SWS_BILINEAR, // option to rescalling
  
                          NULL, //
  
                          NULL, //
  
                          NULL //
  
                          );
  
  
  
  while(
  
  av_read_frame(pFormatCtx, 
  
                  &packet)>=0) 
  
  {
  
  if(packet.stream_index==videoStream) 
  
  {
  
    avcodec_decode_video2(pCodecCtx,
  
                           pFrame,
  
                           &frameFinished,
  
                           &packet);
  
  
  
    if(frameFinished) 
  
    {
  
      SDL_LockYUVOverlay(bmp);
  
  
  
      av_picture_crop((AVPicture*)pFrameCropped,
  
                       (AVPicture*)pFrame,
  
                       (AVPixelFormat)pFrame->format,
  
                       150,
  
                       300);
  
      pict.data[0] = pFrameCropped->data[0];// "X"
  
      pict.data[1] = pFrameCropped->data[1];
  
      pict.data[2] = pFrameCropped->data[2];
  
  
  
      // pict.linesize == number of bytes per line 
  
      pict.linesize[0] = pFrameCropped->linesize[0];
  
      pict.linesize[1] = pFrameCropped->linesize[2];
  
      pict.linesize[2] = pFrameCropped->linesize[1];
  
  
  
      sws_scale(sws_ctx, // the scaling context previously created with sws_getContext()
  
                  (uint8_t const * const *)pFrameCropped->data, // Pointers to the planes of the source slice 
  
                  pFrame->linesize, // the array containing the strides for each plane of the source image 
  
                  0, // position in src img processed slice.  
  
                     // It's number (counted starting from zero) 
  
                     // in the image of the first row of the slice  
  
                  CODEC_HEIGHT, // source slice height. Number of rows in the slice
  
                  pict.data, // pointers to the planes of the destination image 
  
                  pict.linesize); // strides for each plane of the destination image 
  
  
  
      // Unlock SDL_Overlay
  
      SDL_UnlockYUVOverlay(bmp);
  
  }

  Get the compilation error :

  *** glibc detected *** ./HDtoVGA: corrupted double-linked list: 0x08d74e30 ***

  In the FFMPEG command line tool, we can crop a video, using vf_crop (here) but I don’t find how to implement the same function in my code.

  Do you have any hint to help me ?

• Is it possible for FFMPEG built-in command line api to achieve below batch command ?

  24 janvier 2017, par BOBO

  My scenario is listed below :

  1. use ffmpeg to grab videos from their live raw urls and directly convert them into (480px * 480px) .mp4 custom video format with white background if uncovered after resize, disregarding the input video url source might be different in original dimensions, square or rectangular or vertical rectangular etcs.

  code sample is like : (prefer running on local machine, cause faster less costly than run it on server under same hardware spec )

   ffmpeg -i "[raw http video url]"  -vf "scale=iw*min(480/iw\,480/ih):ih*min(480/iw\,480/ih),pad=480:480:(480-iw)/2:(480-ih)/2:color=white" [target_path_and_filename].mp4

  2. when video finished step 1 and saved onto the hard-disk,
     I need to calculate duration of it and retrive information of three frame timestamp in seconds, such as store in an array
     [0, duration/2, duration] using ffprobe

  3. using ffmpeg api command to extract 3 jpeg files
     at the

     0sec frame firstframe.jpg,
     duration/2 (sec) middleframe.jpg,
     and last frame = duration (sec).jpg

  Final step I would like to combine all three steps into one combined task of ffmpeg command line and for loop it in a windows command line batch file.

  so final result of the single batch file, I would like to see if i run :

  loop_ffmpeg_urlvideos_into_3_jpegsets_task.bat video_urls.txt

  output are all those 3 image sets extracted from every row of the url array under one folder if there are [n] lines of vidoes in the video_urls.txt :

  video1_firstframe.jpg video1_middleframe.jpg video1_lastframe.jpg
  video2_firstframe.jpg video2_middleframe.jpg video3_lastframe.jpg
  ......
  video[n]_firstframe.jpg video[n]_middleframe.jpg video[n]_lastframe.jpg

  I’m able to go through the second and third step by using php-ffmpeg library,

  $ffmpeg = FFMpeg\FFMpeg::create();
  
  $video = $ffmpeg->open($video_url);    
  
  $duration = $ffmpeg->getFFProbe()->format($video_url)->get('duration');
  
  
  
  $breakpoints = [0,$duration/2,$duration];
  
  
  
  foreach( $breakpoints as $key=>$breakpoint ):
  
        $jpgfname ="video[$key].jpg"; 
  
        $video
  
         ->frame(FFMpeg\Coordinate\TimeCode::fromSeconds($breakpoint))
  
        ->save( $yoursavepath.'/'.$jpgfname );          
  
  endforeach; 

  but I think it would be greater if all these can be achieved via ffmpeg command line doing 3 steps together.
  so just to loop video_urls from single txt file, and
  run windows bat file at background one time to extract all image sets i wanted without using other 3rd party libraries which might introduce more dependencies on the configuration of [local/remote] server + switching interface from command line CMD.exe to web browser.