Installed, and it works ofc. Good job! Do you kill the process directly? I guess you do, since the front camera indicator led doesn't shut down as it should.
QProcess*proc = new QProcess(); proc->start(streamout);
Settings don't get saved between one session and another one: you may use QSettings to do it.
Ui is fingerfoe: have you set a main layout in desiner?
ShowDebug button is not so needed, it can be swapped with maemo standard banners (QMaemo5InformationBox, and add QT += maemo5 in project file, than run qmake) to save space.
The calibrate window is in window style? Use a message box with detailed text instead (QMessageBox) to be more hildon oriented.
Binary is a bit big just to be a front end. Have you compiled it as release or debug? Package is not optified, it installs in /usr/local/bin