What's a good #format to serialize simple structured #data in an efficient way?

I'm thinking about some binary #XML encoding. Also, #ASN.1 because it natively uses integers, not just strings. Is the packed representation (PER) widely supported?

The data will be a bunch of interleaved time series streams, so variable field lengths could be a big win.

Is there a format for stuff like that?

#Matroska's EBML? Only I'd have to hack the schema in.

#mkv #serialization #formats