Recherche avancée

Sur d’autres sites (7408)

• How save an audio buffer with Fluent FFmpeg

  17 juin 2016, par Luke

  I have a Buffer object that contains audio data and I’m wondering if I can save this Buffer through Fluent FFmpeg without writing it to a file temporary first.

  I came across this other question : fluent-ffmpeg module : "end" event does not fire

  Which seems to do what I need but with video, however, this technique doesn’t seem to work for me. I get the following error :

  ffmpeg write error 'Input stream error: not implemented'

  How can I pipe a Buffer directly to Fluent FFmpeg without writing it to a temporary file first ?

• Automatically detect box/coordinates of burned-in subtitles in a video source

  8 mars 2021, par AndroidX

  In reality I'd like to detect the coordinates of the "biggest" (both in height and width) burned-in subtitle of a given video source. But in order to do this I first need to detect the box coordinates of every distinct subtitle in the sample video, and compare them to find the biggest one. I didn't know where to start about this, so the closest thing I found (sort of) was ffmpeg's bbox video filter which according to the documentation computes "the bounding box for the non-black pixels in the input frame luminance plane", based on a given luminance value :

  


  ffmpeg -i input.mkv -vf bbox=min_val=130 -f null -


  


  This gives me a line with coordinates for each input frame in the video, ex. :

  


  [Parsed_bbox_0 @ 0ab734c0] n:123 pts:62976 pts_time:4.1 x1:173 x2:1106 y1:74 y2:694 w:934 h:621 crop=934:621:173:74 drawbox=173:74:934:621


  


  The idea was to make a script and loop through the filter's output, detect the "biggest" box by comparing them all, and output its coordinates and frame number as representative of the longest subtitle.

  


  The bbox filter though can't properly detect the subtitle box even in a relatively dark video with white hardsubs. By trial and error and only for a particular video sample which I used to run my tests, the "best" result for detecting the box of any subtitle was to use a min_val of 130 (supposedly the meaningful values of min_val are in the range of 0-255, although the docs don't say anything). Using the drawbox filter with ffplay to test the coordinates reported for a particular frame, I can see that it correctly detects only the bottom/left/right boundary of the subtitle, presumably because the outline of the globe in the image below is equally bright :

  


  

  


  Raising min_val to 230 slightly breaks the previously correct boundaries at the bottom/left/right side :

  


  

  


  And raising it to 240 gives me a weird result :

  


  

  


  However even if I was able to achieve a perfect outcome with the bbox filter, this technique wouldn't be bulletproof for obvious reasons (the min_val should be arbitrarily chosen, the burned-in subtitles can be of different color, the image behind the subtitles can be equally or even more bright depending the video source, etc.).

  


  So if possible I would like to know :

  


  

  1. Is there a filter or another technique I can use with ffmpeg to do what I want

  


  2. Is there perhaps another CLI tool or programming library to achieve this

  


  3. Any hint that could help (perhaps I'm looking at the problem the wrong way)

  


  


• Revision 50993 : Mise à jour de Markitup en version 1.1.12 Markitup prenant à peu près en ...

  3 septembre 2011, par marcimat@… — Log

  Mise à jour de Markitup en version 1.1.12
  Markitup prenant à peu près en charge les boutons multiligne, on se base maintenant dessus pour les notres : forceMultiline devient multiline dans la déclaration des boutons.
  On change de technique pour ce qui est du calcul les sélections (sélectionner toute une ligne, tout un mot, au plus proche d’une sélection ou du curseur) : avec les dernières évolutions de Markitup, seul IE se permet des folies. On ne traite donc que le cas IE spécifiquement, et on laisse Markitup gérer les calculs de position du curseur. Du coup, il y a moins de modifications du code de Markitup.
  On n’utilise plus la librairie XRegExp qui ne semble plus utile pour nos calculs d’expressions régulières.
  Testé avec : FF6, IE8, Opera11.52, Chromium 12.0