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• How do I use FFMPEG to pipe in a video file and pipe out a converted video file

  11 avril 2014, par Ranjit Aneesh

  I have very limited knowledge of FFMPEG.
  My use case is that I have a content server with a http url from where I want to pipe in a video file (The video file can be of any format) and I have to convert them to some other format, sometime changing the resolution, and then pipe out and post the video back to the content server.

  I cannot keep a copy of the video file on the local file system where I run ffmpeg since they can be of large sizes and precious time will get wasted in doing so and then calling ffmpeg for conversion and finally writing back the file to content server. I may have to support both Linux as well as windows

  My question is

  1. Is it possbile for FFMPEG to be able to read a file from an http url
  2. Is it possbile to pipe in this data in some other way to FFMPEG if 1 is not possible
  3. Is it possbile to write the data back to a http location by making a ReST put/post call
  4. If 3 is not possbile is there some other way that ffmpeg can push the data back to the server.

  Thanks

• Anomalie #3501 : Les forums supprimés restent en base

  24 juillet 2015, par cedric -

  Je ne suis pas certain que ce soit une bonne idée de purger les forums. Il faut réfléchir aux conséquences.
  Notamment je pense au cas :
  1/ un message de forum diffamant est publié (modération a posteriori)
  2/ tu le vois N jours après et le supprime
  3/ Il reste une trace dans Google ou dans un cache miroir, qui déclenche une action légale
  4/ tu te reçois une requête judiciaire pour avoir l’IP, la date et heure du POST
  5/ et là si tu as pas conservé les forums en base tu es mal.

  Normalement les logs de connexion devraient être conservés 1 an.
  Le fait qu’on masque l’IP par un md5 pour l’anonymiser n’est pas contradictoire, car avec les logs serveurs et l’heure tu peux récuperer les IPs qui ont POST sur ton site et retrouver l’IP avec le md5 si il y en a plusieurs.
  Mais si on supprime les forums on n’est plus en capacité de répondre à une requête judiciaire.

  La suppression des SPAMs est par ailleurs embetante car elle affaiblit la detection des nouveaux spams.

• How to employ DXVA2 with ffmpeg to decode and get frame

  23 juin 2016, par bellekci

  I have searched for a simple example about how to decode H264 stream with hardware acceleration using ffmpeg in Windows but I could not find any.
  I know that I should employ dxva2 with ffmpeg to have hardware acceleration.

  I can decode H264 with ffmpeg on CPU, then convert NV12 format to RGBA and save frames as bmp files, thanks to example project provided in post.

  I have followed what is provided in the following post to get help about dxva2 : post

  I believe I can successfully decode with dxva2 ; however, when I want to get the decoded frame and convert it to RGBA format and save it as bmp file, I get an error about source pointers.

  I decode and retrieve frame as following :

  int videoFrameBytes = avcodec_decode_video2(pCodecCtx_hwaccel, pFrameYuv, &got_picture_ptr, avpkt);
  
  
  
  if (got_picture_ptr==1)
  
  {
  
      if(dxva2_retrieve_data_call(pCodecCtx_hwaccel, pFrameYuv) == 0)
  
      {
  
          fprintf(stderr, "Got frame successfully\n");
  
          result = true;
  
      }
  
  }

  and feed the output frame to :

  sws_scale(pImgConvertCtx, pFrameYuv->data, pFrameYuv->linesize, 0, height, frame->data, frame->linesize);  

  I get this error :

  [swscaler @ 030c5c20] bad src image pointers

  Obviously something is wrong with the pFrameYuv->data but I do not know what.

  How can we convert NV12 frame decoded with DXVA2 to RGBA with sws_scale ?