Also an analog colorspace, YDbDr was used in SÉCAM (Séquentielle ccouleur à mémoire), the French analog TV standard that was also used in Germany, Greece and the Middle east, among others. YDbDr, like the others, use the luminance, Y, and two chrominance components: Db, Dr (for différence bleue and différence rouge).
What’s unusual with this one is how the chrominance components are scaled. Unlike the other colorspaces we’ve seen so far, this one stretches the two chrominance components quite a bit, giving it a squished appearance. Why? It may be that it buys the scheme some tolerance to the frequency modulation used to encode the chrominance components—but I haven’t found anything on this. In fact, just finding documentation on SÉCAM is hard.