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• Seek issue with ffmpeg

  1er janvier 2015, par Ramesh

  I implemented one audio player using with ffmpeg for playing all format audio files in android.I used following code for seek the song.

           int64_t seekTime = av_rescale_q(seekValue * AV_TIME_BASE,
  
                      AV_TIME_BASE_Q,
  
                      fmt_ctx->streams[seekStreamIndex]->time_base);
  
  
  
              int64_t seekStreamDuration =
  
                      fmt_ctx->streams[seekStreamIndex]->duration;
  
  
  
              int flags = AVSEEK_FLAG_BACKWARD;
  
              if (seekTime > 0 && seekTime < seekStreamDuration)
  
                  flags |= AVSEEK_FLAG_ANY;
  
  
  
              int ret = av_seek_frame(fmt_ctx, seekStreamIndex, seek_target,
  
                      flags);
  
  
  
              if (ret < 0)
  
                  ret = av_seek_frame(fmt_ctx, seekStreamIndex, seekTime,
  
                          flags);
  
  
  
            avcodec_flush_buffers(dec_ctx);

  Its working fine for most of the songs.But some of the mp3 songs getting duration problem.For example if the song length is 2 mins if i seek the song to some position then finally song ends with 2 mins 10 seconds.I get this issue with only mp3 songs.Without seeking the same song ends with exact time. I am using ffmpeg 2.1 The some code working fine with ffmpeg 0.11.1 Please provide any information about this issue.

• Acceptable Video Size For Social Network With FFMpeg

  2 août 2022, par John Santos

  I'm building a social network on Android and using FFMPeg to compress the videos before uploading them. Videos will have maximum 1 minute of duration.

  



  The original video for test has 87.74Mb 1080x1920.

  



  Trying to find the middle point between quality and file size I could get to a video size of either 26Mb with an "meh" quality (which I'm not happy with) or 33.06Mb with a good quality (scaling the video to 480x852).

  



  Problems :

  



  1) It's taking an average of 2min 30sec to compress a 1 minute video !

  



  2) Even 25Mb seems to be too much for a 1 minute video for a social network

  



  The ask :

  



  1) Any clue how do Instagram and Facebook do it to compress and upload the same video above within 1 minute !!?? I know they compress it cause the quality is not the same when on Facebook/Instagram but how to they get it done that fast ?

  



  2) What would it be an acceptable file size for a 1 minute video on Facebook/Instagram ? I'm worried about wasting too much storage for 1 minute videos. Does anyone have any idea about it ?

  



  ---

  



  I'm searching a lot about FFMpeg commands to get it better and better but it would be easier if I had in mind what I want to achieve.

  


• ffmpeg streaming simultaneously synchronized delay to multiple social networks

  4 avril 2021, par Jintor

  I'm able to stream simultaneously using ffmpeg to youtube, twitter, facebook, twitch ... simultaneously BUT the issue is the following : each network have their own delay

  


  in 1 network : 15 seconds delay, an other : 10 seconds delay, etc

  


  I tried 2 different ways

  


  • 1 ffmpeg per network => Signal is strong and stable

  


  • 1 ffmpeg with tee muxer to many at once => horrible, unstable, 1 network accepts it and some other says signal poor or too low bitrate...

  


  ----------- for example I use this for each social network ------------------------------

  


  /usr/bin/ffmpeg -re -i input.mp4 -deinterlace -c:v libx264 -pix_fmt yuv420p 
-preset veryfast -tune zerolatency -c:a aac -b:a 128k -ac 2 -crf 18 -r 30 -g 60  
-b:v 2369k -minrate 2369k -maxrate 2369k -ar 44100 -qscale:v 2 -vf "scale=-2:1080" 
-profile:v main -bufsize 2369k -f flv "rtmp://a.rtmp.youtube.com/live2/key"


  


  ---

  


  


  • I know that it's a case by case basis and not easy to do, but Is there a way to "fake" a delay with ffmpeg (like youtube->x delay, facebook-> y delay, etc) ?

    


  


  • or is there any synchronizing mechanism or timing option in ffmpeg ?

    


  


  • or any other approach ?