Oh, and in comment #4, I didn't update the command, but since you said 533 strings, it sounds like you figured it out:
lupdate -extensions cpp,h -source-language en -target-language de . -ts ./res/translations/mixxx_de.ts
Oh, and in comment #4, I didn't update the command, but since you said 533 strings, it sounds like you figured it out:
lupdate -extensions cpp,h -source-language en -target-language de . -ts ./res/translati ons/mixxx_ de.ts