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• what is the best open source framework for programmatically producing .mov or .flv video files ? [closed]

  12 mai 2013, par Andrew Arrow

  I would like to programmatically produce a simple animation video. Don't think "Toy Story" level of animation, think simple stick figures moving around the screen and other very simple lines and dots in black and white only. The point of the video is to explain a complicated scientific concept with a 5 minute video vs. pages and pages of text trying to describe images with words.

  What is the best open source framework to make a .mov or .flv file that I can then upload to youtube or vimeo. I could use ImageMagick to write out jpeg after jpeg, and then ffmpeg to turn those jpegs into a .mov file. But is there a better framework out there for simple animation like this ? I feel like the ImageMagick to ffmpeg route is going to involve a lot of me writing code from scratch to make a stick figure walk across the screen.

• ffmpeg and Youtube upload - can't merge existing audio track with external one

  9 avril 2012, par Aleksy Goroszko

  I am realizing campaign, where idea is that users are creating TV ad. The process looks as following :

  • User watches ad (youtube video)
  • User selects video (mp4 file played in Flash Player)
  • User records his own voice using webcam/mic for the selected video
  • User's voice is uploaded to server
  • User's voice is merged with selected video (video+music) and saved as mp4 file
  • User's video is uploaded to youtube

  When realizing audio-video merging I found some suprises :

  When I was using command

  ffmpeg -i sourceVideoFile.mp4 -i sourceAudioFile.mp3 -acodec copy -vcodec copy outputFile.mp4 - video's music was replaced by user's voice.

  So I used option -newaudio :

  ffmpeg -i sourceVideoFile.mp4 -i sourceAudioFile.mp3 -acodec copy -vcodec copy outputFile.mp4 -newaudio - I can hear that output video has both music and user's voice. So - that's what I wanted to reach. But...

  The surprize is that if I upload this video to Youtube, after it's processing I can watch it and hear only music. User's voice disappears !

  So, how to keep both voice and music ?

  Any idea, gurus ? :)

• Node.js asynchronous video conversion slow

  9 décembre 2016, par lukstei

  I wrote a little website/service, which can download a video from a website (currently Youtube) and converts it on the fly to an mp3 file and sends this file back as the response.

  For example, you when you request http://localhost:8000/v=http ://www.youtube.com/watch?v=HhoewflkQu0, then it will download this video and response the audio layer encoded in MP3.

  This all works very well, my problem is that this is very slow and I can’t figure out why.

  ---

  Simplified the script behaves like this :

  Download the video and write it to the stdin of ffmpeg, and the stdout goes to the response.
  Video (MP4, FLV) -> FFMPEG -> MP3

  I used curl to figure out how fast the script is :

  $ curl http://localhost:8000/v=http://www.youtube.com/watch?v=HhoewflkQu0

  I get only about 5-10k.

  So why is this so slow ?

  1. The server, from which I am downloading the video is slow.
  2. The conversion is slow (because of a slow CPU).
  3. The data transfer between node.js -> FFMPEG is slow.

  I tried to download the video in a normal download manager, and i got about 320k, which is my normal download speed, so the first point isn’t the bottleneck.

  To point 2 and 3, I tried to write a local file to the stdin, and I got about 600k so that isn’t it either.

  So why is my script so slow, and what can I do to make it faster ?

  https://gist.github.com/1304637

  Thanks in advance.