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• What is the relationship among FFmpeg, librtmp and rtmpdump ?

  2 septembre 2021, par yanzhang.guo

  I am a beginner of FFmpeg. I can see that video can be pushed to an RTMP server by FFmpeg or librtmp on the Internet. But I also see that when compiling FFmpeg, I need to add option enable-librtmp. Are they parallel or inclusive ? What is rtmpdump ? Does the libtrmp API use RTMP lower-level functions directly ?

  


• What does Elementary Stream mean in Terms of H264

  5 août 2015, par user1767754

  I read what an Elementary Stream is on Wikipedia. A tool i am using "Live555" is demanding "H.264 Video Elementary Stream File". So when exporting a Video from a Video Application, do i have to choose specific preferences to generate a "Elementery Stream" ?

• Two pass high quality theora/vorbis ffmpeg encoding

  25 septembre 2017, par Lea Chescotta

  I want to achieve the same video encoding that I had with ffmpeg2theora with standard ffmpeg, this is because i need the flexibility ffmpeg has to make the container mkv, with subtitles other than srt.

  In ffmpeg2theora i have the following command that output a very high quality and very small filesize file :

  $ ffmpeg2theora --videobitrate 2000 --two-pass --first-pass firstpass --speedlevel 0 --width 640 --height 360 --resize-method lanczos --noaudio input.mkv
  
  $ ffmpeg2theora --videobitrate 2000 --two-pass --second-pass firstpass --speedlevel 0 --width 640 --height 360 --resize-method lanczos --noaudio input.mkv --output output.ogv

  Being the most interesting options here i think (From ffmpeg2theora manual page) :

  --two-pass
  
  --first-pass <filename>
  
  --second-pass <filename> 
  
  --speedlevel
  
      encoding is faster with higher values the cost is quality and bandwidth (default 1)
  
  </filename></filename>

  But i can only found a simple way to encode theora/vorbis in standard ffmpeg (from : https://trac.ffmpeg.org/wiki/TheoraVorbisEncodingGuide) :

  ffmpeg -i input.mkv -codec:v libtheora -qscale:v 7 -codec:a libvorbis -qscale:a 5 output.ogv

  That produces a very bad quality output even in the best quality setting (10)

  How can I do a 2 pass ’high quality’/’not so big filesize’ theora/vorbis in plain ffmpeg ?