A picture decoding method, comprising: obtaining a current picture of a video, which is segmented by using random access points into multiple video segments supporting a random access function, wherein the multiple video segments are referred to as random access segments; selecting, from a knowledge base, K reference pictures of the current picture, wherein at least one picture in the knowledge base does not belong to a random access segment in which the current picture is located, and K is an integer greater than or equal to 1; and decoding the current picture according to the K reference pictures; wherein selecting, from the knowledge base, K reference pictures of the current picture comprises: selecting, from the knowledge base, the K reference pictures of the current picture based on a reference picture index of the current picture that is obtained by decoding a first video bitstream to which the current picture belongs; and characterized in that the method further comprises: if no reference picture that matches the reference picture index is found from a second video bitstream, requesting, from a server, an incremental bitstream of the second video bitstream that comprises a reference picture that matches the reference picture index, decoding the incremental bitstream of the second video bitstream to obtain the reference picture that matches the reference picture index, and using, as a reference picture of the current picture, the obtained reference picture that matches the reference picture index and wherein at least one picture in the knowledge base is obtained by decoding the second video bitstream. obtaining a current picture of a video, which is segmented by using random access points into multiple video segments supporting a random access function, wherein the multiple video segments are referred to as random access segments; selecting, from a knowledge base, K reference pictures of the current picture, wherein at least one picture in the knowledge base does not belong to a random access segment in which the current picture is located, and K is an integer greater than or equal to 1; and decoding the current picture according to the K reference pictures; wherein selecting, from the knowledge base, K reference pictures of the current picture comprises: selecting, from the knowledge base, the K reference pictures of the current picture based on a reference picture index of the current picture that is obtained by decoding a first video bitstream to which the current picture belongs; and characterized in that the method further comprises: if no reference picture that matches the reference picture index is found from a second video bitstream, requesting, from a server, an incremental bitstream of the second video bitstream that comprises a reference picture that matches the reference picture index, decoding the incremental bitstream of the second video bitstream to obtain the reference picture that matches the reference picture index, and using, as a reference picture of the current picture, the obtained reference picture that matches the reference picture index and wherein at least one picture in the knowledge base is obtained by decoding the second video bitstream. if no reference picture that matches the reference picture index is found from a second video bitstream, requesting, from a server, an incremental bitstream of the second video bitstream that comprises a reference picture that matches the reference picture index, decoding the incremental bitstream of the second video bitstream to obtain the reference picture that matches the reference picture index, and using, as a reference picture of the current picture, the obtained reference picture that matches the reference picture index and wherein at least one picture in the knowledge base is obtained by decoding the second video bitstream.