I followed these instructions here on this link below to remove a black background from an image and to render preserving both the RGB and Alpha channels for transparency. I used to use a black background and blend in screen mode but sometimes the image is too transparent so I wanted to be able to key out the background.
I did a good job in using Keylight and creating what I needed with a green background and keying out the green, however the finished render output results in a HUGE uncompressed .avi file that plays in a herky-jerky fashion. Any suggestions on what codec I should use within the After Effects render cue for AVI files? It's unfortunate in that I spent all day creating many video files after keying out the green, only to be left with virtually unplayable files that quickly gobbled up all my free space on my main drive. I use a Windows machine and most of the videos with an alpha channel from online sites like Video Hive use a MOV format for Apple Quicktime and I would like to be able to play back in Windows Media Player. Thank you,
As a workaround I used the Quicktime format and will import these files into After Effects. Much smaller than the avi files and no herky jerky animation.
Even this is a stopgap solution until I can get good at creating my own presets for motion paths on objects and text... I started out creating videos in Power Point and this program has some handy presets for their animations so I found it easier to create a video with the objects with the animations I wanted, key out the background and save the result as an RGB+Alpha video so i can use it as an overlay in my compositions. Eventually I will be able to do all of this in After Effects and will no longer need Power Point 2013 as it is simply an office presentation tool and not a full blown video creation and effects program like After Effects or Premiere Pro is. Power Point also has some psuedo extruded text options by using bevels and character outlines (stroke in After Effects) and doesn't take 30 hours to render a 50 second MP4 video file like ray-tracing or Cineware in After Effects does. Eventually I will invest $2500 in a high end nVidia workstation graphics card as I've been building my own gaming PCs since 2006.