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• how to explain this C language code from ffmpeg remuxing

  20 avril 2017, par Fidona

  can someone help me what the meaning of this code ? this is a code from ffmpeg remuxing code.

  static void log_packet(const AVFormatContext *fmt_ctx, const AVPacket *pkt, const char *tag, int hours, int mins, int secs, int us, int *time )
  
  {
  
      AVRational *time_base = &fmt_ctx->streams[pkt->stream_index]->time_base;
  
      total = total + pkt->duration;
  
    //  printf( "%d:%d:%d.%d \n", hours,  mins,  secs, us );
  
      *time = av_q2d(*time_base) * pkt->pts ;
  
  }

  I’m kind of new to C language. thank you !

• ffmpeg override the same file for every second of the video [on hold]

  5 février 2017, par Dorin Pleava

  I want to get one image for every 10 seconds from a livestream/video, but the image should have the same name, meaning I want to override it every cycle.

  This is my command :

  ffmpeg.exe -i http://iphone-streaming.ustream.tv/uhls/17074538/streams/live/iphone/playlist.m3u8 -bt 20M -s 480x300 -vf fps=1/10 -y photo.jpg

  This code works for one image but for the next I get this

  "Could not get frame filename number 2 from pattern ’photo.jpg’ (either set updatefirst or use a pattern like %03d within the filename pattern)
  av_interleaved_write_frame() : Invalid argument"

  If I replace photo.jpeg with photo%03d.jpg I get photo001.jpec, followed by photo002.jpeg, etc.

• Issue regarding concatenate videos ffmpeg

  8 février 2021, par Mayank Thapliyal

  I want to concatenate 3 videos using ffmpeg. So I did a research on the net and got the required code. But later on I realized that it will not work as the attributes of the video are different and hence I will have to re-encode the videos

  


  So I got this on the internet :-

  


  ffmpeg -i 1.mp4-i 2.mp4 -i 3.mp4 -filter_complex "[0:v] [0:a] [1:v] [1:a] [2:v] [2:a] concat=n=3:v=1:a=1 [v] [a]" -map "[v]" -map "[a]" output.mp4

  


  But when I ran it,it was SUPER slow. And ffmpeg recommended to add vsync 2 in the code. I added it in the following manner :-

  


  ffmpeg -i 1.mp4-i 2.mp4 -i 3.mp4 -vsync 2 -filter_complex "[0:v] [0:a] [1:v] [1:a] [2:v] [2:a] concat=n=3:v=1:a=1 [v] [a]" -map "[v]" -map "[a]" output.mp4

  


  Now the video was processed on time and the result was also fine. But I don't know the meaning of the code. Will someone be kind enough to explain what exactly is happening ? (in this way I would be sure that the code will always work for me for all videos)