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• ffmpeg record audio from Xvfb on Centos

  25 mai 2017, par boygiandi

  I’m trying to record audio from Xvfb. And I have some problems :

  1. What’s the different between alsa and pulse. I get confuse
  2. Server Centos have no soud card :

  arecord -l

  arecord : device_list:268 : no soundcards found...

  3. I may have many Xvfb process, how to record video and audio from specific Xvfb process. I checked this https://trac.ffmpeg.org/wiki/Capture/ALSA#Recordaudiofromanapplication but still don’t understand how it works.

  ffmpeg -f alsa -ac 2 -i hw:0,0 -acodec pcm_s16le output.wav

  I seen many command like this, but I don’t know how to get hw:0,0 ( id of sound card ? )

  Please help. Thanks

• choosing outbound IP (eth0 or eth1) in FFMPEG

  4 septembre 2018, par Ba Ta

  I have 2 IP addresses on my server.

  $curl --interface eth0 ifconfig.co      
  
  111.111.111.111
  
  
  
   $curl --interface eth0:0 ifconfig.co      
  
  222.222.222.222

  So via curl I can switch via interfaces so my IP address changes when I visit any url based on eth IP

  How can I use same thing via ffmpeg ?

  For example, if want to access this video via ffmpeg (it uses 111.111.111.111 to access it)

   ffmpeg -i 123.com/video.mp4

  how can I access same video from my second IP 222.222.222.222 ?

  Is there any command like this, perhaps ?

  ffmpeg --interface eth0:0  -i 123.com/video.mp4

• ffmpeg, add static image to beginning and end with transitions

  14 mars 2021, par CreateChange

  ffmpeg noob here, trying to help my mother with some videos for real estate walkthroughs. I'd like to set up a simple pipeline that I can run videos through and have outputted as such :

  


  

  • 5 second (silent) title card ->

  


  • xfade transition ->

  


  • property walk through ->

  


  • xfade transition ->

  


  • 5 second (silent) title card

  


  


  Considerations :

  


  

  • The intro / outro card will be the same content.

  


  • The input walkthrough videos will be of variable length so, if possible, a dynamic solution accounting for this would be ideal. If this requires me to script something using ffprobe, I can do that - just need to gain an understanding of the syntax and order of operations.

  


  • The video clip will come in with some audio already overlaid. I would like for the title cards to be silent, and have the video/audio clip fade in/out together.

  


  


  I have gotten a sample working without the transitions :

  


  ffmpeg -loop 1 -t 5 -i title_card.jpg \
    -i walkthrough.MOV \
    -f lavfi -t 0.1 -i anullsrc \
    -filter_complex "[0][2][1:v][1:a][0][2]concat=n=3:v=1:a=1[v][a]" \
    -map "[v]" -map "[a]" \
    -vcodec libx265 \
    -crf 18 \
    -vsync 2 \
    output_without_transitions.mp4


  


  I have been unable to get it to work with transitions. See below for the latest iteration :

  


  ffmpeg -loop 1 -t 5 -r 60 -i title_card.jpg \
    -r 60 -i walkthrough.MOV \
    -f lavfi -t 0.1 -i anullsrc \
    -filter_complex \
    "[0][1:v]xfade=transition=fade:duration=0.5:offset=4.5[v01]; \
    [v01][0]xfade=transition=fade:duration=0.5:offset=12.8[v]" \
    -map "[v]" \
    -vcodec libx265 \
    -crf 18 \
    -vsync 2 \
    output_with_transitions.mp4


  


  This half-works, resulting in the initial title card, fading into the video, but the second title card never occurs. Note, I also removed any references to audio, in an effort to get the transitions alone to work.

  


  I have been beating my head against the wall on this, so help would be appreciated :)