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• How to insert bullet screen comments into a video by using ffmpeg ?

  7 septembre 2019, par Saeron Meng

  I would like to add some real-time comments in my video but I do not know how to use ffmpeg to realize this. The comments are like screen bullets through the screen, scrolling from right to left.

  My thought is to count the length of the comments and define speeds for them to move. Don’t worry about the source of the comments, I have already gotten them saved as an xml file. Also, I can transfer it into srt. For instance :

  <chat timestamp="671.195">
  
      <ems utctime="1562584080" sender="Bill">
  
          <richtext></richtext>
  
      </ems>
  
  </chat>
  
  <chat timestamp="677.798">
  
      <ems utctime="1562584086" sender="Jack">
  
          <richtext></richtext>
  
      </ems>
  
  </chat>

  The final result is like this (I did not find an example displayed in English), these fancy characters can move horizontally :

  

  I have searched some solutions on the Internet, most of which talk about how to write ass/srt files and add motionless subtitles. Like this :

  3
  
  00:00:39,770 --> 00:00:41,880
  
  When I was lying there in the VA hospital ...
  
  
  
  4
  
  00:00:42,550 --> 00:00:44,690
  
  ... with a big hole blown through the middle of my life,
  
  
  
  5
  
  00:00:45,590 --> 00:00:48,120
  
  ... I started having these dreams of flying.

  ffmpeg -i infile.mp4 -i infile.srt -c copy -c:s mov_text outfile.mp4

  But I need another kind of "subtitles" which can move.

  So my question is, how to modify the ffmpeg command and the template of srt file so as to arrange the subtitles from the top to the bottom and let them move from right to left ?

• ffmpeg screen, audio und mike recording

  6 mai 2022, par DRRDietrich

  So far I've been working with SimpleScreenRecorder to record screen and system sound. But now I also need the audio track from the microphone, which doesn't work reliably with SimpleScreenRecorder. So I tried ffmpeg, which worked right away. However, there still seems to be a problem with the time synchronization of the tracks, which probably causes the first few seconds of my recording to be broken.

  


  I get the following message :

  


  


  Queue input is backward in time

  


  Non-monotonous DTS in output stream 0:1 ; previous : X, current : Y ; changing to X. This may result in incorrect timestamps in the output file.

  


  


  That's the command I'm using. I would prefer an output with two separate audio tracks, but this solution is okay too.

  


  ffmpeg  -video_size 1920x1080 -framerate 25 \
        -thread_queue_size 1024 \
        -f x11grab -i :0.0+0,0 \
        -f pulse -ac 1 -i ${SYSTEMSOUND} \
        -f pulse -ac 1 -i ${MICROPHONE} \
        -filter_complex "[1:a][2:a]amix[a]" \
        -map 0:v -map "[a]" \
        ${OUT}.mkv


  


  How can I improve the script ?
The option -thread_queue_size 1024 was already helpful, although I'm not entirely sure what it exactly does.

  


• ffmpeg android-prepare video from images according to sound file

  16 décembre 2013, par Sameer Z.

  I am working app which create the video from many screen(images).
  I can prepare video from screen.
  Now to select the no of frames depends on the pitch of the audio,for example
  for 1 sec only 3 frames and another sec 5 frames.The audio files are static.

  Please let me know your thoughts how i can achieve this.

  Thanks in advance.