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• Is it possible to use FFMPEG to generate F4V videos ?

  10 juillet 2012, par James Raber

  I need to generate a script that converts videos to F4V's for use with Flash Media Server 4.5...is this possible ? I have it converting files to MP4s and then swapping the extension. This works fine, but seems like a dirty work around. I'd prefer to use a generate a true F4V. I've heard mixed things on whether or not ffmpeg truly supports F4Vs. Any guidance would be appreciated. Also, is there a doc guide on what file formats are allowed by FFMPEG ?

• How to create videos with small file size but large resolution ?

  13 février 2017, par Gregory Magarshak

  Is there a programmatic way to create videos that capture, essentially, a powerpoint presentation, that would be not much larger than the audio + screenshots of the powerpoint itself ?

  I want to make software that produces videos with the full resolution of a powerpoint on a large screen, and with a person speaking over it and wvwn doodling. Kind of like "bcontext" software. And then I want to export videos for youtube and other places to be hosted. But I want them to be SMALL. So they can be downloaded by people with slow connections eg in India.

  What factors can affect video size and how can i take advantage of the relative "stillness" of most pixels at most times to make the compression preserve the full sharpness and yet take advantage of the lack of visual changes ? What software do you recommend ?

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

  29 juin 2017, 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.