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• Does ffmpeg support clip feature in ass with subtitle filter ?

  14 mars 2019, par neonew

  I want to use clip/iclip feature in ASS with ffmpeg to display the subtitles one by one. Below is my ASS file content :

  [Script Info]  
  
  ScriptType: v4.00+  
  
  WrapStyle: 0  
  
  ScaledBorderAndShadow: yes  
  
  PlayResX: 1000  
  
  PlayResY: 560  
  
  [V4+ Styles]  
  
  Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding  
  
  Style: Default,FZLanTingHei-R-GBK,24,&H000000,&H00FF0000,&H00000000,&H00000000,0,0,0,0,100,100,0,0,2,0,0,1,0,0,0,1  
  
  [Events]  
  
  Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text  
  
  Dialogue: 0,0:00:00.00,0:00:02.00,Default,,0000,0000,0000,,{\pos(717,91)\iclip(717,91,1000,191)\t(0,1000,\iclip(1000,91,1000,191))}Hello World!

  ffmpeg command :

  ffmpeg -i input.mp4 -filter_complex "subtitles=myass.ass" output.mp4

  However, the text just appeared two seconds, but didn’t have clip feature.
  So, is there something wrong ?

• How to know the delay of frames between 2 videos, to sync an audio from video 1 to video 2 ?

  8 janvier 2021, par jaimepm

  world.

  


  I have many videos that I want to compare one-to-one to check if they are the same, and get from there the delay of frames, let's say. What I do now is opening both video files with virtualdub and checking manually at the beginning of video 1 that a given frame is at position, i.e., 4325. Then I check video 2 to see the position of the same frame, i.e., 5500. That would make a delay of +1175 frames. Then I check at the end of the video 1 another given frame, position let's say 183038. I check too the video 2 (imagine the position is 184213) and I calculate the difference, again +1175 : eureka, same video !
The frame I chose to compare aren't exactly random, it must be one that I know it is exactly one I can compare to (for example, a scene change, an explosion that appears from one frame to another, a dark frame after a lighten one...) and I always try to check for the first comparison frames within the first 10000 positions and for the second check I take at the end.
What I do next is to convert the audio from video 1 to video 2 calculating the number of ms needed, but I don't need help with that. I'd love to automatize the comparison so I just have to select video 1 and video 2, nothing else, that way I could forget forever virtualdub and save a lot of time.

  


  I'm tagging this post as powershell too because I'm making a script where at the moment I have to introduce the delay between frames (after comparing manually) myself. It would be perfect that I could add this at the beginning of the script.

  


  Thanks !

  


• Building FFmpeg for Android

  13 juin 2013, par varevarao

  I've spent almost a week on this now, trying to get FFmpeg "Angel"/"Happiness" to build for Android.
  I've tried build scripts from all over the internet to no avail. I got closest was using this. As the author himself says the script doesn't work for newer versions of FFmpeg due to this bug, which has been dismissed on that ticket saying "I found a Makefile that does it." This was dis-heartening, being the only post on all of the vast Google world that was anywhere close to my problem.
  So, question time :

  Is there a way to get around the above bug ? I'm trying to use the newest ffmpeg API, and "Love" is just giving me "undefined reference" errors while trying to use av_encode_video2(), and av_free_frame(). The code I was working on the lines of is at the ffmpeg git repo, under /doc/examples/decoding_encoding.c (the function starting on line 338).

  Update : So they've done away with codec_names.sh in "Angel". Sorry didn't notice that before, but the problem persists in a different avatar now. With every build attempt the compiler throws a certain

  start ndk-building...
  
  /home/<user>/android-ndk/build/core/build-binary.mk:41: *** target file `clean&#39; has both : and :: entries.  Stop.
  
  </user>

  Say whatnow !?