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• How to create thumbnails of videos with Meteor, CollectionFS, & FFMPEG

  24 juin 2015, par Jared Martin

  I’m using Meteor with CollectionFS to store videos. I need a transform to create thumbnails of my videos.

  Videos = new FS.Collection("videos", {
  
    stores: [
  
      new FS.Store.FileSystem("thumbs", { 
  
        transformWrite: function(fileObj, readStream, writeStream) {
  
          // What goes here?
  
        }
  
      }),
  
      new FS.Store.FileSystem("videos"),
  
    ],
  
  });

  I’ve worked out how to do this with ffmpeg :

  ffmpeg -i video.mp4 -vf  "thumbnail,scale=640:360" -frames:v 1 thumb.png

  But I’m not sure how to do this with the readStream I’m given and output the writeStream.

  Here’s an example of how it is done with images using GraphicsMagick :

  Images = new FS.Collection("images", {
  
    stores: [
  
      new FS.Store.FileSystem("thumbs", { 
  
        transformWrite: function(fileObj, readStream, writeStream) {
  
          // Transform the image into a 10x10px thumbnail
  
          gm(readStream, fileObj.name()).resize('10', '10').stream().pipe(writeStream);
  
        }
  
      }),
  
      new FS.Store.FileSystem("images"),
  
    ],
  
  });

  Although the samples use the local filesystem, Ill be using cvs:dropbox, so you can’t rely on the file being there locally.

• concatenate mp4 videos with ffmpeg concat demuxer in android

  6 mai 2016, par Ara Badalyan

  I want to concatenate mp4 videos with ffmpeg, the problem is when I want to merge videos taken with Iphone and Android it throws problem

  " Non-monotonous DTS in output stream 0:1 ; previous : 150528, current : 139268 ; changing to 150529. This may result in incorrect timestamps in the output file."

  This is my code

  merge.txt

  file 'iphone.mp4'
  
  file 'android.mp4'

  ffmpeg command

  ffmpeg -f concat -i marge.txt -c copy -y merge.mp4

  If I can’t merge this videos how can i make them with same parameters (frame rate, bitrate...) and merge them ?

  P.S I use ffmpeg version 2.4.2 , because I can’t find android ffmpeg library higher then 2.4.2.

• creating thumbnails from multiple videos

  28 septembre 2020, par blue

  I have multiple videos, and i want to create a thumbnail image for each video.i also want the image thumbnails to have the same names as the videos and have specific width/height.

  
Is it also possible to have ffmpeg create thumbnails with a specific aspect ratio and instead of stretching the video it could add black bars ?

  
Now i don't know a thing about how ffmpeg works so i looked up a tutorial online and configured it,tested out a simple script and it worked.

  
i found what the script i was looking for but i don't know a thing about bash scripts so it just throws an error and i don't how to figure it out.
  

  


  for f in *.mp4; do ffmpeg -i "$f" -ss 00:00:03 -vframes 1 -s 480x320 "${f%.mp4}.jpg"; done