One of the smartest projects I've ever seen was a tool that took the human-readable tables of the HEVC and AV1 specs, used them as input to https://en.wikipedia

One of the smartest projects I've ever seen was a tool that took the human-readable tables of the HEVC and AV1 specs, used them as input to https://en.wikipedia.org/wiki/OMeta https://en.wikipedia.org/wiki/OMeta parser-generator, and then output both HEVC parsers in a variety of languages and also auto-fuzzers for test coverage. Ended up at https://www.graphcore.ai/posts/graphcore-open-sources-argon-streams-av1-video-decoder-verification-tool https://www.graphcore.ai/posts/graphcore-open-sources-argon-... Personally I've also written a parser-generator for XML in C# to overcome some of the odd limitations of Microsoft's one when used in AOT contexts. Hand-rolling is easy if the grammar is small. The larger it gets (and video codecs are huge!) the more you want something with automatic consistency.