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• ffmpeg for archval and convertability

  26 juillet 2021, par Satya

  I've got a couple hundred gigs of *.dv files. I'd like to convert them to H.264 or something else or even leave them alone. The purpose is archival, with an eye to maximum convertability especially to DVD. The content is family videos.

  


  Would this be fine ?

  


  ffmpeg -i input.dv \
    -c:v libx264 -preset slower \
    -crf 17 \
    -pix_fmt yuv420p \
    output.mp4


  


  I went with the slower preset because encoding time isn't an issue and I'd like a smaller file size. crf 17 is for least-lossy while being widely playable. I read somewhere that yuv420p is needed for some Quicktime players.

  


  Should I throw in -c:a aac for AAC audio ? The audio is voice only, no need for music-hall quality.

  


  I looked at https://trac.ffmpeg.org/wiki/Encode/H.264 for previous research and that's where I got those settings, but it is silent on the audio settings.

  


• SDL2 C++ Capturing Video of Renderer Animation/Sprite

  27 octobre 2016, par alok

  I have an animation/sprite created using SDL2. The animation works fine when it is being rendered to a screen. But now I also want it to be recorded into a video file (locally stored). For this, I am planning on using FFmpeg APIs, to which I’ll be sending a raw RGB pixel data array.

  My problem is with fetching the data from SDL2 APIs.

  What I’ve tried is :

  // From http://stackoverflow.com/questions/30157164/sdl-saving-window-as-bmp
  
  SDL_Surface *sshot = SDL_CreateRGBSurface(0, 750, 750, 32, 0x00ff0000, 0x0000ff00, 0x000000ff, 0xff000000);
  
  SDL_RenderReadPixels(gRenderer, NULL, SDL_PIXELFORMAT_ARGB8888, sshot->pixels, sshot->pitch);
  
  
  
  // From https://wiki.libsdl.org/SDL_RWFromMem
  
  char fName[50];
  
  sprintf(fName, "/tmp/a/ss%03d.bmp", fileCnt);
  
  
  
  
  
  char bitmap[310000];
  
  SDL_RWops *rw = SDL_RWFromMem(bitmap, sizeof(bitmap));
  
  SDL_SaveBMP_RW(sshot, rw, 1); 

  Above does not work. But dumping a single frame into a file with following code works :

  SDL_SaveBMP(sshot, "/tmp/alok1/ss.bmp")

  This obviously is not an acceptable solution - Writing to thousands of BMPs and then using FFmpeg from command-line to create a video.

  What am I doing wrong ? How do you extract data from SDL_RWops ? Is the use of SDL_RWFromMem the right approach to my problem statement ?

• How to install libavcodec and libavutil from its source in linux

  25 janvier 2017, par neckTwi

  FFMPEG is providing libavutil and libavcodec libraries. While compiling and installing ffmpeg as described at https://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu I can find libavcodec and libavutil folders in the ffmpeg source folder. I want to install these libraries to use them in my c++ programs. But there are no Makefiles in these folders. How can I install them ?