Method and system for video switching

The invention discloses a method and a system for video switching. The method comprises the steps of advertisement acquisition: analyzing the advertisement address and acquiring an advertisement; acquiring a key frame, namely acquiring a key frame of the positive slice; performing first switching: and when the key frame is played to the key frame or before the key frame is stored, the key frame field is stored, and taking a certain key frame as a first switching point; and the positive plate is switched to the advertisement when the first switching point is in the first switching point, and setting a first audio and video label when the positive film is played in front of the first switching point or the first switching point, the first audio and video label is used for identifying the audio and video source type of the front and back features of the switching point and the advertisement; and the switching operation between the positive film and the advertisement is carried out according to the first audio an