Because some old LCD TV is not really point to point pixel.
Like my 32" TV, it's real resolution is 1360x768 but it also support the HD 1080i.
When play video with chromecast, the screen is cut off around the edge of the video,
I really want a function to scale the output size.
To my knowledge, the pixel issue was called overscan.
I had tried the engineer mode with my TV, but nothing work (it might too old in 2006).
even the newest gpu card also have some problem like this.