Cross-platform video conversion tool + Python ( Gstreamer ? )

I'm开发者_如何学编程 looking for a tool to do the following:

1. Convert video/audio from multiple formats to WebM format.
2. Needs to be command-line or Python-binded.
3. Cross-platform.
4. No royalty licenses - Thus, all FFMpeg-based tools are out - See this for an explanation.

The best framework I've found so far is GStreamer, But I'm not sure if it's cross-platform or if gst-python is cross-platform. I've installed GStreamer on my mac using homebrew, but it's missing some elements (i.e. alsasink), and I don't think I can compile gst-python for Mac. They require pygtk. Everything there is linux-based (-only!) :(

Know anything else that might do the trick? Or how can I fix Gstreamer + gst-python to work properly on mac/win/linux altogether?

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you can try FFMPEG for format conversion. FFMPEG v.0.6 adds support for VP8 (WebM)