Which file converter do I write for education, fun and real-world application?

I am looking for some real-world application task which singlehandedly will give me some programming experience. I am thinking about file format converter but I am not sure about which pair of formats to chose. I would prefer a binary or mixed formats as more trickier ones. Which of existing file format conversion would you suggest to 开发者_如何学Gome to look at ?

Thanks in advance

BMP - TGA image file conversion is an appropriate start. This also allows you to add more formats as you progress.

A converter from .fsdb to .ltx, .ltx2, .fst and the other way around ( .ltx, .ltx2, .fst to .fsdb ) would be very very nice to have.

The .ltx, .ltx2, .fst are formats used and understood by gtkwave waveform viewer. The gtkwave is very capable open source waveform viewer used in digital/mixed signal design community.

The .fsdb is the proprietary format used in the commercial waveform viewer verdi (former 'debussy').