Comment by truekonrads

My few rules are: 1) What's the entropy? This helps with encrypted/compressed. You probably need to overcome this? 2) What's the context? Apps are developed in context and context suggests formats. Is it C? Then expect structs. Does it need to go over the wire? Expect run-length encodings. Python/JS - JSON/pickle. 3) There are broadly speaking only a few ways you can read data back into memory: fixed layout, run-length encoding, terminators. A great case-study is ASN.1, once you've built an ASN.1 parser by hand no file format will ever daunt you.