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• mov : Evaluate the movie display matrix

  3 novembre 2016, par Vittorio Giovara

  mov : Evaluate the movie display matrix
  This matrix needs to be applied after all others have (currently only
  
  display matrix from trak), but cannot be handled in movie box, since
  
  streams are not allocated yet. So store it in main context, and apply
  
  it when appropriate, that is after parsing the tkhd one.
  Signed-off-by : Vittorio Giovara <vittorio.giovara@gmail.com>
  

  • [DH] libavformat/isom.h
  • [DH] libavformat/mov.c

• How to add subtitles to PowerPoint presentation

  5 septembre 2018, par ppdlx

  Okay, to clear things up I will say that I’m posting here because I found the answer and want to help people in future who come upon the same problem. Since PowerPoint is not the right tool to title an presentation I will tell you my way of doing this. If you can do it in PowerPoint alone, super for you but I could not do it in PowerPoint alone, therefore this way. So what I did is the following, I simply recorded the presentation and made subtitles for it and in the final I hardcoded the subtitles into the video. Here is how I did it.

  How to add subtitles to your PowerPoint presentation

  First, I downloaded the latest SnagIt software from their official website. You can have a free trial there. Click here to download SnagIt. Then using SnagIt I recorded my whole screen and played the presentation. I made a video file of the presentation. Let’s call it presentation.mp4.

  Then I downloaded my subtitle making software, an awesome open source program called Subtitle Edit from it’s official website. It’s really simple to use it and it is awesome and user friendly. It doesn’t take too long to subtitle a three minute presentation. When you are satisfied with the subtitles save them as .srt and call them whatever you like. Now we have a video file and corresponding subtitles for it.

  Now we need to hardcode the subtitles into the video file, in other words to burn the subtitles to the video. I did this using another awesome open source software called ffmpeg. See the website and download it from official ffmpeg website. Extract it somewhere and for convinience put subtitle and video file to it’s bin directory. You can put it elsewhere if you like it that way. The first command I used is to transform .srt to .ass.

  ffmpeg -i subtitles.srt subtitles.ass

  Afterwards it’s easy to make a subtitled video file with the following command :

  ffmpeg -i presentation.mp4 -vf ass=subtitles.ass presentation_subtitled.mp4

  I am not sure for the command and can’t get now to see the correct command but if it fails you can seek help on this page.

  Now that we have our presentation_subtitled.mp4 we can now trim the video to our likings.

  ffmpeg -i presentation_subtitled.mp4 -ss 00:01:00 -to 00:02:00 -c copy presentation_final.mp4

  Of course, edit the -ss and -to option, it’s the start time and the end time of your video.

  That’s it ! Now you have your presentation_final.mp4 video file where you have your presentation with subtitles. Ffmpeg is awesome because you can convert it to any format you like.

  You have some help with hardcoding subtitles on Subtitle Edit web page, but one software gave me a virus, one software didn’t work, and after trial and error this is the way that worked for me and it’s really convinied due to great open source software - Subtitle Edit and ffmpeg.

• Does ffmpeg has multiple hls webvtt subtitles

  3 avril 2018, par sandeep

  I am trying to use ffmpeg to generate multiple webvtt hls subtitles.But ffmpeg considering only one subtitle in the hls output.
  Please let me know if ffmpeg can support multiple webvtt subtitles for hls .