Recherche avancée

Sur d’autres sites (5427)

• How to speed up video conversion

  3 février 2021, par Arheisel

  I'm currently working in a project that involves converting large series of .jpg (>6000) into video format. These frames (320x240) are stored in folders at a rate of 2.5fps. Generating a couple of folders every hour that need to be converted ASAP.

  


  For now I've tried copying the folder to a ram disk and using avconv which takes about a minute.

  


  Here is my command :

  


  avconv -threads auto -y -r 2.51 -i %03d-capture.jpg -s 320x240 -r 25 video.mpeg


  


  

  • Could ffmpeg work faster ?

  


  • Is there a way to speed it up ?

  


  • Which video format takes less time to convert to ?

  


  


• Multiple frames lost if I use av_read_frame in FFmpeg

  12 juin 2015, par Krishna

  I have an HEVC sequence with 3500 frames and I am writing a decoder for reading it (read frame by frame and dump to yuv). In my main(), I have a for loop that calls a decoder() 3500 times (I am assuming at this stage that the main() knows how many frames there are).

  So, for every call to decoder(), I need a complete frame to be returned. This is what the decoder() looks like..

  bool decode(pFormatCtx, pCodecCtx)
  
  {
  
      int gotaFrame=0;
  
  
  
      while (gotaFrame==0) {
  
  
  
          printf("1\t");
  
  
  
          if ( !av_read_frame(pFormatCtx, &packet) ) { 
  
              if(packet.stream_index==videoStreamIndex) {
  
  
  
                  // try decoding
  
                  avcodec_decode_video2(pCodecCtx, pFrame, &gotaFrame, &packet);
  
  
  
                  if (gotaFrame) {  // decode success.
  
  
  
                      printf("2\t");
  
  
  
                      // dump to yuv ... not shown here. 
  
  
  
                      // cleanup
  
                      av_frame_unref(pFrame);
  
                      av_frame_free(&pFrame);
  
                      av_free_packet(&packet);
  
  
  
                      return true;
  
                  }
  
              }
  
          }
  
      }
  
  }

  The behavior is like this : 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 2 1 2 ...... it looks like it reads several frames before decoding one ? The first frame is an I-frame, so shouldn’t that be decoded right away ?

  With this code, I end up losing the several frames (indicated by the series of 1s). Can someone help me out here ? Is there something I am doing wrong in my code ?

  Update : the test clip is video-only. No audio.

• How to record a video conference (e.g skype, oovoo, ...) with a program written in C#

  13 août 2014, par Matin Lotfaliee

  I want to record screen (a video conference e.g skype, oovoo, ...) with a program written in C#. I searched a lot about how to do this :

  • Here suggests Windows Media Encoder, but none of their samples work correctly on my Win7. I installed the SDK but even the links to Microsoft are somehow broken or old.
  • Here suggests creating a video stream from a series of screenshots using ffmpeg. but it is probably impossible to keep the audio,mic and screenshots synced.
  • Here suggests creating a GIF file, but it does not support audio which is important to me.
  • Here suggess using Gallio framework, but I was unable to find where the usable DLL for recording is.
  • Here seems to be a great solution but it is not free...

  Compression is not important to me because a video conference uses CPU a lot.

  Can you help me find a good and easy solution with references ?