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• how to change the fps of video during playback of video without restarting video

  8 juin 2018, par Mahek Delawala

  I want to change the fps of video at run time (during the playback of video) without restarting or pausing using ffmpeg. I searched about it in the internet but I am not able to get the command which can change the fps directly without restarting the video but i found ffmpeg command which can create a new file with modified fps as shown below.
  ffmpeg -y -r 20 -i input_file -r 45 output_file
  Is it possible to change fps of video during run time using ffmpeg command ? If yes please provide me the command if not how can i change using c code. Please help me in this issue as early as possible.
  Thank you.

• Getting 500 error when uploading video to twitter from android app

  11 juillet 2016, par Sakshi

  I am trying to compress video using FFMPEGAndroid library using the following command.

  {"-y" ,"-i", file.getAbsolutePath(),
  
  "-c:v", "libx264", "-crf", "20",
  
  "-aspect", "1:1",
  
  "-pix_fmt", "yuv420p",
  
  "-c:a", "aac", "-strict","experimental",
  
  "-b:a", "96k", "-ac", "2", "-ar", "44100",
  
  "-preset", "ultrafast",
  
  "/storage/emulated/0/output.mp4"}

  When I try to share the video on Twitter from my android app, I get 500 Internal Server Error. I am able to share same video on Facebook and on my app. I have been read a lot of forums and FFMPEG manuals but no luck.

• How do I create a 360 [stereo] panorama video of a virtual scene using OpenGL or DirectX ?

  14 novembre 2015, par Prashant Raina

  Like many of you, I have seen the magical 360 degree videos doing the rounds on Facebook right now. I would really like to know how to programmatically create such a video using OpenGL or DirectX, but I found surprisingly little information about it.
  There are several issues I am not clear on :

  1. How do I set up my vertex and fragment shaders to render a frame of 360 video ?
  2. Do I have to generate one image per frame, or a cubemap, or something else ?
  3. Once I have the frames, how do I combine them into a single video file for upload ? My Googling suggests that I should use ffmpeg, but I couldn’t figure out which parameters to use, or what sort of input it expects for 360 video.
  4. What additional steps are needed to make a stereo 360 video ?

  I am not asking how to render an existing video onto the screen, or how to use physical cameras for 360 video.

  Thanks in advance !