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• Web-based video editor

  10 octobre 2014, par Danny

  We have a web-based editor currently that allows users to build animated web apps. The apps are made up of shapes, text, images, and videos. Except for videos, all other elements can also be animated around the screen. The result of building a animated app is basically a big blob of JSON.

  The playback code for the web app is web-based as well. It takes the JSON blob and constructs the HTML, which ends up playing back in some sort of browser environment. The problem is that most of the time this playback occurs on lower-end hardware like televisions and set-top boxes.

  These performance issues go away if there is some way to be able to convert a digital sign to video. Then the STB/smart TV simply plays a video, which is much more performant than playing back animations in a web view.

  Given a blob of JSON describing each layer and how to draw each type of object, its animation points, etc, how could I somehow take that and convert it to video on the server ?

  My first attempt at this was using PhantomJS to load the playback page in a headless browser, take a series of screenshots, and then use ffmpeg to merge those screenshots into a video. That worked great so long as there is no video. But it does not work with video since there is no HTML5 video tag support in PhantomJS, and even if there was, I would lose any audio.

  The other way I was thinking of doing it would be to again load the playback page in PhantomJS, but turn off the video layers and leave them transparent, then take screenshots as a series of PNGs with transparency. I would then combine these with the video layers.

  None of this feels very elegant though. I know there are web-based video editors out there that basically do what I’m trying to accomplish, so how do they do it ?

• ffmpeg - why I have three video streams in the output file when I have one video input (one video stream), one logo input

  17 juillet 2024, par Yazhou

  Hi I'm using ffmpeg to transcode some video files from prores or dv to h264/mov. Also I want to add a logo on it and make some other changes.
The command line I use is

  


  ffmpeg -i input.mov -i logo.png -c:a aac -c:v libx264 -pix_fmt yuv420p -crf 18 -map 0:a? -map 0:v -filter_complex "yadif,[1]scale=iw*1:-1[wm];[0:v:0][wm]overlay=main_w-overlay_w-5:5" -disposition:v:0 default output_h264.mov

  


  And what I got has three video streams. One for the logo,one for the video with logo, and one for original video.

  


  Though I put the default video stream as the one with both video and logo as you can see for -disposition:v:0 default, and it's also playing that stream. But when I tried to upload it on Vimeo or Youtube, it uses the wrong stream.

  


  ---

  


  How can I change the command line to let ffmpeg only output one stream ?
And how can I remove the extra streams for the existed outcomes ?

  


• FFMPEG - Merge multiple video in to one video, the output video has no audio

  26 octobre 2018, par Tan Pham

  My input file has 5 video and 1 picture. I want to merge all video to one video, play video at the same time.
  The layout of the output video like this :
  

  Im using ffmpeg to merge video. this is my ffmpeg command :

  ffmpeg 
  
  -i C:\VID\test1.mp4 
  
  -i C:\VID\test2.mp4 
  
  -i C:\VID\test3.mp4 
  
  -i C:\VID\test4.mp4 
  
  -i C:\VID\test5.mp4 
  
  -i C:\VID\background.jpg 
  
  -filter_complex 
  
  " nullsrc=size=1280x720 [base]; 
  
  [0] setpts=PTS-STARTPTS, scale=560x360 [video0];
  
   [1] setpts=PTS-STARTPTS, scale=280x180 [video1]; 
  
  [2] setpts=PTS-STARTPTS, scale=280x180 [video2];
  
   [3] setpts=PTS-STARTPTS, scale=280x180 [video3];
  
   [4] setpts=PTS-STARTPTS, scale=280x180 [video4]; 
  
  [5:v] scale=700x700 [image]; 
  
  [base][video0] overlay=shortest=1 [tmp1]; 
  
  [tmp1][video1] overlay=shortest=1:y=360 [tmp2];
  
   [tmp2][video2] overlay=shortest=1:x=280:y=360 [tmp3]; 
  
  [tmp3][video3] overlay=shortest=1:y=540 [tmp4]; 
  
  [tmp4][video4] overlay=shortest=1:x=280:y=540 [tmp5];
  
   [tmp5][image] overlay=570:10:enable='between(t,0,30)'"
  
   -t 30 -c:v libx264 output.mkv

  The output video layout is working fine but no audio in the output video.
  I want all audio off each video will be keep on the output video. play audio at the same time together.
  I’m using tutorial on this link : Create a mosaic out of several input videos
  Thanks for reading