I’ve created the ebml package: ebml: A pure EBML parser. Its main goal is to enable serving a webm stream by splitting the initialization segments from the media segments. You can also use this library to parse the Extensible Binary Meta Language (EBML), webm and mkv file format.
The library provides a stream parser on top of the binary incremental decoder, and I’d love to get some feedback on the implementation 
Cheers,
-Tristan
Congratulations on the release!
I’ve been looking into ways to generate WebP pictures, especially animated ones. I assume your library just provides support for the container format, but but not for encoding the image data inside?
Also see
Hmm, nevermind, WebP even seems to use a different container format (RIFF).
That is correct, my EBML library only supports the container format. RIFF looks very similar and simple, but you would also need to implement the VP8 key frame codec to generate WebP.
By the way, I wrote a blog post about a motivating use-case for EBML here: Broadcasting a WebM stream using MSE – Tristan's Zettelkasten