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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 ?

• Format ffmpeg command to extract the full klv for an mpg/ts file

  24 décembre 2020, par Andrew Marquez

  I am extracting the KLV data from an mpg file using klvdata and ffmpeg.

  



  Following the readme, I have downloaded the sample "Day Flight.mpg" video file that contains KLV data. Running the quick start command works (I get the exact same result as the readme example for the first 6 frames.)

  



  However, for the life of me I don't know how I can extract the KLV data for the entire video file.

  



  As an experiment, I tried creating the KLV data file from an offset start :

  



  ffmpeg -ss 5 -i Day\ Flight.mpg -map data-re -codec copy -f data - > out.klv


  



  and when I run it through my code with different start times (5, 25, etc.) I do get different results.

  



  This (to me) would suggest that the mpg file does contain KLV data throughout, but I can only access 6 frames at a time.

  



  I would expect to be able to run an ffmpeg command to output the full KLV data. I need help formatting my ffmpeg command to properly provide all the data.

  



  To replicate, download the "Day Flight.mpg" file from the klvdata project page and run the command I posted above. You will note it is less than a page long. It should be many, many pages long. Thank you for your help !

  


• ffmpeg taking so much time to extract frames from mpeg-ts file

  19 septembre 2016, par Syed Azaruddin

  I got a problem from one mpeg-ts video. Actually it was created by some one else and even I don’t know how they are created. The problem is that, ffmpeg is taking so much time to decode all frames from the mpeg-ts video. The command I used for this operation is...

  ffmpeg -i shame-run.mov -r 24/1 test/output%d.jpg

  Actually my application is integrated with ffmpeg v2.1.1. and I had a code for detecting black frames in a mpeg-ts video. Here, my code is not able to detect all black frames from ffmpeg for this mpeg-ts video. So, I taken standalone ffmpeg of same version as mentioned above and decoded standalone. But, it is taking so much time i.e., it is taken half an hour for decoding 1 min duration video.

  So, is there any reason is that ffmpeg not able to extract as fast as required, and is there any reason that video got some errors.