25. The method of claim 23 , wherein determining a second resolution of the source video comprises setting a resolution adjustment level based on the video coding complexity of the source video.
23. The method of claim 16 , wherein determining an optimal resolution for the source video comprises: receiving the source video having a first video format and a first resolution; obtaining a video coding complexity score of the source video; determining a second resolution of the source video based on the video coding complexity; and encoding the source video into an output video having the second resolution and a predetermined video output format.