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• OpenCV videowriter H264 codec (ffmpeg)

  18 juin 2019, par alcon

  I want to save a video with opencv with lossless compresion so I don’t lose any details of the frames. Everything works with the xvid codec but offcourse this is not a lossless compression so I found that the x264 codec is suitable. However it doesn’t work, I tried the following sample code but while running I get the following error : "could not find encoder for codec id 28 : encoder not found."

  cv::VideoWriter makeVideo;
  
  makeVideo.open("makevideo//newVideo.mp4", CV_FOURCC('X','2','6','4'), 30, cv::Size(1600,1200), true);
  
  cv::Mat image = imread("makevideo//frames//111.png");
  
  
  
  for(int i = 0; i < 200; i++)
  
      makeVideo << image;
  
  
  
  makeVideo.release();

  I found that for this to work, I need to have ffmpeg support. I’m currently using opencv2.4.6 and in this discussion (how can I use the openCV FFMPEG video I/O rather than the DirectShow one in Windows ?) someone mentioned that in opencv2.4 ffmpeg is automatically included. But its not working....

  Here (How to compile OpenCV 2.3 with ffmpeg support with Visual Studio 2010) I found how to compile opencv and ffmpeg yourself on windows. I followed all the steps sucessfully but still I get the same error....

• Can't see logs of x264 lib

  21 octobre 2013, par mkd156

  I have a C++ solution which uses x264.lib. I've set params.i_log_level = X264_LOG_DEBUG; in order to be able to see some logging from x264 lib. However during debugging in Visual Studio Output window I do not see any x264 related logs.

  How can I see those logs ?

• Better vertical stabilization when simultaneously cropping to widescreen format

  21 juillet 2016, par Kelley van Evert

  First of all : forgive me for maybe asking a stupid or somewhat uninformed question. I’m totally new to post processing video, stabilization, etc..

  I’m shooting 1920x1080 compressed movie files with my Canon 5D2, and afterwards crop then to cinematic 1920x800 (2.4:1). (With Magic Lantern I use an overlay bitmap when shooting. And yes, I know that with magic lantern I can shoot RAW, but my cards as well as computer are not fast enough to deal with that much data.)

  Before doing any production, I convert the big .MOV files to smaller ones, simultaneously stabilizing the video a bit, and cropping it to 1920x800. I do this with ffmpeg roughly as follows :

  ffmpeg -i f.MOV -vf vidstabdetect -f null -
  
  ffmpeg -i f.MOV -c:v libx264 -profile:v high -crf 18 -vf "vidstabtransform, crop=in_w:in_h-280" -c:a aac -strict experimental f2.mp4

  However, the fact that a great deal of the vertical resolution is being cropped is not being used to be able to handle the stabilizing transforms better. Often, the image is stretched/skewed vertically, when this is not really needed given the crop used.

  Is it possible in any way to use the crop befenificially in the stabilizing transforms ?

  An example is the frame below. Here, I would rather have that the image is not stretched vertically at all, and just get away with a slight static zoom (crop), because the horizontal black border is the only problem in this frame.