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• ffmpeg speed encoding problem

  15 septembre 2011, par amrouch

  I am currently developing an application that makes capturing video from a webcam on Linux using the Qt Designer tool and V4L2 and ffmpeg libraries under C + +, to capture the image there is no problem using lib V4L2, and since That a picture is ready I send it to the encoder which is based on ffmpeg libs, initially the encoder creates a video file, and it receives images to encode it in this file, my problem is as follows : the encoding is normally done, but after if I start playing the recorded video file, speed appears to be accelerated compared to the regular speed ! So what is clear, the problem is in video encoding,
  my question is, is there a method or function that manages ffmpeg encoding speed pictures ?????
  thank you for your help.

• FFMPEG Error initializing complex filters when using watermark [duplicate]

  13 décembre 2019, par Ahmed T

  This question already has an answer here :

  • How to add transparent watermark in center of a video with ffmpeg ?
    
    1 answer
    

  Im trying to convert mp4 file using ffmpeg on windows by using this command ,

  ffmpeg -i 1.mp4 -vcodec libx264 -movflags +faststart -threads 0 -r 25 -g 50 -crf 25 -me_method hex -trellis 0 -bf 8 -acodec aac -strict -2 -ar 44100 -ab 128k -vf subtitles=1.srt:force_style='FontName=Changa,Fontsize=20' -qscale:v 3 -preset veryfast 1z.mp4

  its converted without problem but i need to use png watermark file to be converted with the video bottom right i have tried all options using search but no one works sometimes i got problem for complex rules , im a new with ffmpeg and i dont know how to do it , your help really appreciated .
  Thanks

• Speed problems with realtime recording with libavcodec and libavformat

  1er novembre 2022, par WalleyM

  I am trying to use libavcodec and libavformat to write an mp4 video file in realtime using h264. I am using an approach heavily inspired by this answer here This works well as a non-realtime solution however, avcodec_receive_packet() starts running much slower after 20 frames or so (this is usually around the first time it returns success and thus av_interleaved_write_frame() is called for the first time). This is so slow that my writing cannot work in realtime.

  


  Solutions I have tried :

  


  

  • Enabling multithreading on my codec context

  


  • Running avcodec_receive_packet() and av_interleaved_write_frame() on a separate thread to my capture from the realtime video source

  


  • Changing the gop_size in the video context

  


  • Lowering my bitrate in the video context

  


  


  Is there anything I'm missing ? Possibly some fundamental rules to capturing video in realtime. I am not very experienced with programming with video.