Gamma shifts/ Color shifts depend on a million settings liek what CoDec is used, how your project color space is set up, what source footage or even general color settings on your system. You have to provide a lot more info.
footage : HD - xdcam ex 1080 50i (35 mb/s vbr )
color settings :
depth 8 bit
working space : none
codec :xdcam ex 1080 50i (35 mb/s vbr )