A video data processing apparatus provided according to one embodiment of the present invention includes a processor and a blending circuit. The processor provides a first set of parameters according to a first channel identification signal and a second set of parameters according to a second channel identification signal. The blending circuit blends a first image into first video data at a first timing according to the first set of parameters and a second image into second video data at a second timing according to the second set of parameters. A time difference between the first timing and the second timing is less than a frame period of the first video data.