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• Static ffmpeg library windows

  29 novembre 2022, par peter

  Im trying to use the ffmpeg libraries (libavutil, libswscale, ...) in a bigger project by statically linking them, im not interested in the binaries. Now the issue comes down to getting them statically built. I tried searching for pre-compiled builds but without success.

  


  Following the docs, i compiled them on wsl2 for win64 with

  


  ./configure --arch=x86_64 --target-os=mingw32 --cross-prefix=i686-w64-mingw32- --disable-shared --enable-static
make


  


  After that i copied the libavformat/libavformat.a as libavformat.lib (which should be fine since they are cross-compiled ar archives ?) into my project and linked them with CMake.

  


  When compiling smth like

  


  AVFormatContext* pFormatContext = avformat_alloc_context();


  


  i get a linker error saying

  


  lld-link : error : undefined symbol: avformat_alloc_context


  


  When looking at the libs with dumpbin -linkermember libavformat.lib, i can see

  


  >dumpbin -linkermember libavformat.lib
...
  135CD92 _avformat_alloc_context
...


  


  notice the underscore.

  


  Can i not link the cross-compiled *.a files directly into a windows executable ?

  


  Honestly at this point any ideas are welcome.

  


  Thanks

  


• ffmpeg : How to add an image to the end of a video, freeze framing the last frame and using a fade

  26 novembre 2019, par Jeremy Thomerson

  (I’ve looked at a number of other similar questions, but can’t find any with an answer that actually works)

  I often need to combine a short video clip with in image. Typically, the video clip is a short explanation of a concept, followed by an image that helps the user visualize the concept. Rarely do the frame sizes / resolution of the video and image match. Typically, I need every second of the video clip to display, so even though I would like a cross-fade between the video and image, I’d like to freeze-frame the final frame of the video, and then cross-fade between that frozen frame and the following image.

  I’d like both the video and image, despite the disparity in their resolutions, to "fit to frame", such that I get an output that’s either a) the size of the larger asset, or b) some fixed size (like 720p), and in either case, both the image and video are scaled to fit into those dimensions, while maintaining their original aspect ratio.

  For example, given the following two assets (video and image), how could I accomplish what’s described above ? (Note : these assets are just ones I found that are available for examples, and not the actual type of content I’d be using ; however, they do accurately represent the disparity in resolution and aspect ratio I’d often have between video and image file).

  • https://file-examples.com/wp-content/uploads/2017/04/file_example_MP4_640_3MG.mp4
  • https://upload.wikimedia.org/wikipedia/commons/e/e8/World_blank_map_countries.PNG

  Bonus : At times, I’d like to :

  1. Reverse the order (image, and then video), or
  2. Have a video and then multiple images, one after the other, faded between each, or
  3. Video, fade to image, then more video

  Note : I’m running ffmpeg on Mac / OSX, installed via brew

  Thanks so much if you can help !

• How to directly record screen in .mp4 format using ffmpeg in Windows10 ? [on hold]

  9 août 2019, par Alex Salagean

  I have been using .gifs to make short screen recordings but as the video duration gets longer, the file size also gets a lot larger. Therefore, I want to directly record my screen in a .mp4 format.

  I have tried making a .gif animation using multiple separate images and then converting them to .mp4 via ffmpeg but I need a command which lets me directly record the screen using the .mp4 format.