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• HTML5 Video FFMPEG Shell Script

  18 novembre 2011, par Schermy

  I wrote this quick and dirty shell script to run ffmpeg over a bunch of files to generate webm/ogg/h.264 videos for a HTML5 site.

  #!/bin/bash
  
  
  
  ext=$1
  
  enc=$2
  
  
  
  #!/bin/bash
  
  for file in *.$ext; do
  
          while pidof /usr/local/bin/ffmpeg; do sleep 10; done >/dev/null
  
  
  
          ffmpeg -i "$file" -s 1280x720 -b 500k  "${file/%$ext/$enc}"   
  
  done

  It works great for my purposes but I've noticed that each video now takes a lot longe to convert and ffmpeg is not taking advantage of my multi-core setup.

  I would like to improve this script when I have some time and make it available for use by others but I'd like to solve this issue first.

  Thanks in advance for all of your help.

  P.S. This is setup to use the ffmpeg installation from brew on the Mac (and yes I would like to make this script more platform agnostic later on).

• Turn image sequence into video with transparency

  29 janvier 2014, par Cody Hatch

  I've got what seems like it should be a really simple problem, but it's proving much harder than I expected. Here's the issue :

  I've got a fairly large image sequence consisting of numbered frames (output from Maya, for what its worth). The images are currently in Targa (.tga) format, but I could convert them to PNGs or other arbitrary format if that matters. The important thing is, they've got an alpha channel.

  What I want to do is programatically turn them into a video clip. The format doesn't really matter, but it needs to be lossless and have an alpha channel. Uncompressed video in a Quicktime container would probably be ideal.

  My initial thought was ffmpeg, but after wasting most of a day on it it seems it's got no support at all for alpha channels. Either I'm missing something, or the underlying libavcodec just doesn't do it.

  So, what's the right way here ? A command line tool like ffmpeg would be nice, but any solution that runs on Windows and could be called from a script would be fine.

  Note : Having an alpha chanel in your video isn't actually all that uncommon, and it's really useful if you want to composite it on top of another video clip or a still image. As far as I know uncompressed video, the Quicktime Animation codec, and the Sorenson Video 3 codec all support tranparency, and I've heard H.264 does as well. All we're really talking about is 32-bit color depth, and that's pretty widely supported ; both Quicktime .mov files and Windowss .avi files can handle it, and probably a lot more too.

  Quicktime Pro is more than happy to turn an image sequence into a 32-bit .mov file. Hit export, change color depth to "Millions of Colors+", select the Animation codec, crank the quality up to 100, and there you are - losslessly compressed video, with an alpha chanel, and it'll play back almost anywhere since the codec has been part of Quicktime since version 1.0. The problem is, Quicktime Pro doesn't have any sort of command-line interface (at least on Windows). ffmpeg supports encoding using the Quicktime Animation codec (which it calls qtrle), but it only supports a bit-depth of 24 bits.

  The issue isn't finding a video format that supports an alpha channel. Quicktime Animation would be ideal, but even uncompressed video should work. The problem is finding a tool that supports it.

• Apply video effects

  11 octobre 2013, par ishan jain

  I am creating an application, in which I have to give the option to apply different effects (normal, sepia, black & white, vintage, HD) to the VIDEO. I am creating this application for android version 2.3 .
  I am thinking of following the flow video -> convert to image frames -> apply effect to frames using some library -> convert frames to video.

  Can anyone help me that if above flow is correct or not ? And which library I can use for applying effects to the frames or is there any other way to apply the effects to the video ?

  Thanks