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• ffmpeg subtitles alignment and position

  7 mai 2024, par friendlygiraffe

  I am adding subtitles to a video using :

  



  ffmpeg -i "imput.mp4" -lavfi "subtitles=subtitles.srt:force_style='OutlineColour=&H100000000,BorderStyle=3,Outline=1,Shadow=0,Fontsize=18'" -crf 1 -c:a copy "output.mp4"


  



  Which results in :

  



  

  



  I am repositioning this using Alignment :

  



  ffmpeg -i "imput.mp4" -lavfi "subtitles=subtitles.srt:force_style='Alignment=9,OutlineColour=&H100000000,BorderStyle=3,Outline=1,Shadow=0,Fontsize=18'" -crf 1 -c:a copy "output.mp4"


  



  

  



  But according to the Line-Alignment ASS Tags docs, there are only 9 positions. 1 : Bottom left, 2 : Bottom center, 3 : Bottom right, 5 : Top left, 6 : Top center, 7 : Top right, 9 : Middle left, 10 : Middle center, 11 : Middle right

  



  Is there a way to tweak this positioning ?

  



  I want the subs to be left-aligned, but lower down. Like this :

  



  

  


• Using ffmpeg to stream to Facebook Live Video : can preview, but not go live

  17 novembre 2016, par Einar Magnússon

  I am trying to stream a webpage to Facebook Live video using ffmpeg. I know I can use OBS, but I’m trying to do it from a server, so I can’t go with OBS. It works fine when I’m previewing, but as soon as I press ’Go live’, at first it seems like it’s starting, but then when it takes me to the live view it just says that the video has ended. I even checked the error of the video log using Graph API, nothing. I’m using PhantomJS to pipe screenshots to ffmpeg :

  phantomjs phantom.js | ffmpeg -y -c:v mjpeg \
  
  -f image2pipe \
  
  -r 5 -i \
  
  - -c:v libx264 \
  
  -x264-params keyint=5 \
  
  -b:v 1000k -minrate 1000k -maxrate 1000k -bufsize 500k \
  
  -f flv 'rtmp://rtmp-api.facebook.com:80/rtmp/xxxxxxxxxxxxxxxx'

  As I said, it’s working fine in the preview of the live stream on Facebook, but just ends immediately when I go live. I added the bitrate options to try to keep a constant bitrate as mandated by Facebook (https://developers.facebook.com/docs/videos/live-video/production-broadcasts), and I have a keyframe every 5 frames (rather low frame rate at 5fps) so that requirement is fulfilled as well.

  I’m not sending any audio, could that cause a problem ?

• Compiling FFMPEG on CentOS DigitalOcean

  29 juillet 2015, par coder_uk

  I set up a DigitalOcean instance running CentOS 6.5 and successfully followed the guide to compile FFMPEG (https://trac.ffmpeg.org/wiki/CompilationGuide/Centos). Hurrah !

  But of course I realised that by default, DigitalOcean creates a root user and so ffmpeg now lives in /root/bin/ffmpeg. Which isn’t ideal because when I want to exec the ffmpeg bin from nginx, I would have to run nginx as root for it to have permission.

  Questions ...

  1) Long-shot, but presumably if I change the owner of the ffmpeg binary to nginx, it still won’t work, because nginx won’t be able to access the /root folder it is in. Correct ?

  2) I could run nginx as root (’user root’). But this seems like a very bad idea. Correct ?

  3) Which leaves me with the option of creating a new user, and then compiling ffmpeg into its home folder. But : which user ? EC2 creates ’ec2-user’, so should I make my own equivalent for DO ? But then won’t I have to run nginx as that user, else I’ll run into the same problem ?

  Or should I compile ffmpeg into the ’nginx’ home folder, if indeed it has one ? Is that how it is supposed to be done ?

  Since compiling ffmpeg takes ages, I don’t want to keep doing it, and the static files all seem very out of date. Thanks