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• FFMpeg Out of sync audio/video in iOS application

  28 juillet 2016, par yogbd

  The app saves the camera output into a mov. file, then turn it to flv format that sent by AVPacket to rtmp server.
  It switch every time between two files, one is written by the camera output and the other one is sent.
  My problem is that the audio/video is getting out of sync after a while.

  The first buffer sent is allways 100% sync but after awhile it get messed.
  I belive its a DTS-PTS problem..

   if(isVideo)
  
  {
  
      packet->stream_index = VIDEO_STREAM;
  
     packet->dts = packet->pts = videoPosition;
  
      videoPosition += packet->duration = FLV_TIMEBASE * packet->duration * videoCodec->ticks_per_frame * videoCodec->time_base.num / videoCodec->time_base.den;
  
  
  
  }
  
  else
  
  {
  
      packet->stream_index = AUDIO_STREAM;
  
      packet->dts = packet->pts = audioPosition;
  
      audioPosition += packet->duration = FLV_TIMEBASE * packet->duration / audioRate;
  
  
  
     //NSLog(@"audio position = %lld", audioPosition);
  
  }
  
  
  
  packet->pos = -1;
  
  packet->convergence_duration = AV_NOPTS_VALUE;
  
  
  
  // This sometimes fails without being a critical error, so no exception is raised
  
  if((code = av_interleaved_write_frame(file, packet)))
  
  {
  
      NSLog(@"Streamer::Couldn't write frame");
  
  }
  
  av_free_packet(packet);

• FFmpeg : Is it better to make a application then using ffmepg directly

  14 juillet 2020, par Mirabeau

  For all my IP camera streams, I use, under Linux, ffmpeg by a bash script which allows me at the same time to manage :

  


  1/ Convert the RTSP streams to HTTP (HLS) for the "Live" and therefore which generates "m3u8" file and *.ts segments

  


  2/ Backup the stream for archiving (in increments of 5 minutes), a cron remove older files (xx days)

  


  ffmpeg -i "rtsp://[IP_CAM01]" -rtsp_transport tcp -c copy -map 0 -f segment -segment_time 300 -segment_atclocktime 1 -segment_format mkv "cam01-% 03d.mkv" -c copy -f segment -segment_list cam01.m3u8 -segment_list_flags + live -segment_time 2 -segment_list_size 20 -segment_wrap 20 cam01-% 03d.ts


  


  The question I ask myself, and the reason for this message is as follows :

  


  

  • would there be an interest (memory / cpu / speed) to develop a program (C/C++/other ?) to do the same thing by using the libraries of ffmpeg ?

  


  • or the "gain" and the interest would be so minimal that it is not worth the expenditure of energy and time ?

  


  


  I appeal to your feedback, your opinions, your tips !, and if you had leads (sample) to attack this kind of development, I am interested.

  


  Thank you very much in advance for your feedback.
(this is my fist question on stackoverflow, Champagne ! ;))

  


• Save two video streams in one video file c#, Windows 8 application [on hold]

  19 septembre 2014, par manos

  I am developing a Windows store application which will be able to record video from two video sources (e.g. two usb cameras or usb camera and embeded tablet camera) and then save the two video streams in one video file. So, when the saved video will play, it will show a large video frame (video from camera 1) and inside that, in the top right corner, a smaller video frame (video from camera 2). Basically, i want to render one video on top of the other. I think the process is called picture in picture, but I am not 100% sure. I am able two capture the 2 video streams (same length, same video quality) but I do not know how to proceed after that. How to do the rendering. Do I save the streams into two files and then process those files or do i need to process the streams directly (merge them) and then save to file ?
  I have read that you can do something like that by using ffmpeg libraries. But so far I have not managed to find any c# code to it. Any ideas ?

  Thanks in advance,
  Manos