Method for shortening display latency based on variable refresh rate technology and related rendering device thereof

A rendering device for controlling a display device with a variable refresh rate function, comprising:

• a decoding unit configured to receive a video stream and decoding the video stream to generate a plurality of decoded video frames;
• and
• a refresh rate control unit, coupled to the decoding unit, configured to determine a frame ready time for each of the decoded video frames, and a frame display time for each of the decoded video frames, and accordingly determine a target refresh rate for the display device based on a frame latency between the frame ready time and the frame display time corresponding to at least one of the decoded video frames;
• wherein the rendering device is configured to control the display device to display the video stream at the target refresh rate.