I teach 3D animation at the University of Colorado at Boulder, and am frequently asked by students how they can get their hands on free or cheap image editors (for preparing textures), video editors (for rendering video segments from the single frames rendered by AutoDesk Maya, the most popular 3D animation application), and editing soundtracks for animated videos.
If you are looking for free tools to flesh out your workflow for your project, consider:
1. The following is a free video editor. I know it has a very loyal following: redshark. This runs on windows; the mac version is not available yet. There is also a linux version.
2. This is a free app that is both a sound editor (cutting and pasting and trimming chunks of wave files) and a mixer (blending multiple layers, like voice and music into a single layer): audacity. This runs on macs and windows.
3. This is a free video editor from Microsoft that runs on windows. It is very simple but other students tell me they have used it: Movie Maker.
4. This is a free image editor that runs on macs and windows. It is very powerful: GIMP.
5. This is an audio editor that runs on Windows and Macs. I THINK, but am not sure that there is a free version. I couldn’t find a direct link to it on their site. It might be that you need to download the not-for-free version and then use it in trial mode: WavePad. To download their mac version, you need to be on a mac, and to download their windows version, you need to be on a windows machine.
They also happen to have a video editor and I don’t know if there is a free version:VideoPad. The video editor is, however, windows-only. It is relatively inexpensive.
6. All macs should have garageband on it. This is actually a full mixing program, as well as a host for electronic instrument plugins, but it can be used as a sound editor alone.
7. This is a free image editor for windows: paint.net. It is very basic, but I have done a few interesting things with it.