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• How can I create videos from images with transitions in C# ?

  4 septembre 2021, par Kjensen

  Using C# code, I want to take a number of images, add some music and create a video.

  


  I think I can best explain what I want in pseudo-code... :

  


  var video = new Video(1080, 1920); //create a video 1080*1920px 
video.AddFrame("C:\temp\frame01.jpg", 2000); //show frame for 2000ms
video.AddTransition(Transitions.Fade, 500); //fade from first to second frame for 500ms
video.AddFrame("C:\temp\frame02.jpg", 1000); //show frame for 1000ms
video.AddTransition(Transitions.Fade, 500); //fade from second to third frame for 500ms
video.AddFrame("C:\temp\frame03.jpg", 2000); //show frame for 2000ms
video.AddSound("C:\temp\mymusic.mp3"); //added from start of video
video.Save("C:\temp\MyAwesomeVideo.avi", Format.MP4);


  


  Does something like this exist ?

  


  I know there are a couple of older libraries, that can do some stuff with ffmpeg to create slideshows, but I looked at some of them, and they are insanely tricky to get working - and designed for something quite different.

  


  Backstory :

  


  I created a system for a cinema, which every week generates x number of images using movie posters, showtimes etc - and would like to take those images, turn them into a video which will be shared on social media.

  


• ffmpeg : error while loading shared libraries : libopenh264.so.5 [closed]

  6 avril, par ESZ

  I am using ffmpeg and getting this error

  



  
ffmpeg: error while loading shared libraries: libopenh264.so.5: cannot open shared object file: No such file or directory


  



  I have already checked if the library exists and it does. I added it to /etc/ld.so.conf as mentioned in this previous question but it doesn't work.

  


• What is the optimal way to synchronize frames in ffmpeg c/c++ ?

  16 septembre 2022, par Turgut

  I made a program that read's n number of video's as input, draws those videos to the GLFW window and finally encodes it all as a singular video output. The problem is frames of each video in question can be different, it's dependent on the user's input.

  


  For example : the user can put two video's which has an FPS of 30 and 59, and can want an output 23,797. The problem is those video's are not in sync with each other, thus on the output we can see that the input video's are either faster or slower.

  


  Duration of each video is also dependent on the input. For example, in accordance to the previous example, the first input might be 30 second and the second can be 13 second, while the output is 50 seconds.

  


  I mostly read the frames similar to a moving png rather than a solid video since there are no iframe and bframes. There are just data I get from the GLFW window.

  


  As an example, let's say we give one video as input which has an FPS of 30 and duration of 30, and our output has an FPS of 23.797 and duration of 30. I have 2 function's skip_frame and wait_frame which respectively either read's a frame twice so we skip a frame or don't read the frame on that iteration. Those function's are used depending on the situation, whether it's output < input or output > input.

  &#xA;

  Here is what my code roughly looks like :

  &#xA;

  while(current_time < output_duration){
   for(auto input_video: all_inputs){
      for(int i = 0; i < amount_to_read_from_input(); i++){
         frame = input_video.read_frame();
      }
   }
   
   GLFW_window.draw_to_screen(frame);

   encoder.encode_one_video_frame(GLFW_window.read_window());
}


  &#xA;

  Basically skip_frame and wait_frame are both inside amount_to_read_from_input() and return 2 or 0 respectively.

  &#xA;

  So far I have tried multiplying duration with fps for both input and output. Then getting the result of their subtraction. Going from our previous example we get 900 - 714 = 186.&#xA;Then I divide the result to the output fps like so : 714 / 186 = 3.8. Meaning that I have to skip a frame every 3.8 iterations. (I skip a frame every 3 iterations and save the residual 0.8 for the next iter.)

  &#xA;

  But it's still a seconds or two behind. (Like it ends at 29 seconds for a 30 second output.) and the audio is out-of-sync. Ffmpeg handles my audio so there are no errors on that part.

  &#xA;

  Also seen this question but I don't think I can utilize ffmpeg's function's here since im reading from a glfw window and it comes down to my algorithm.

  &#xA;

  The problem is what is the math here ?

  &#xA;

  What can I do to make sure these frames are stabilized on almost every input/output combination ?

  &#xA;