A method for use in encoding and decoding pictures in a video stream, comprising: identifying a current picture in the video stream for encoding or decoding; identifying a collocated picture for inter prediction of the current picture, wherein identifying the collocated picture includes: indicating, depending on a state of a flag, whether the collocated picture can be located using a first collocated picture index list or a second collocated picture index list; if the flag is in a first state: providing a first reference picture set number that indicates a total number of reference pictures in the first collocated picture index list that are available for inter prediction of the current picture; and determining if the first reference picture set number indicates that there is more than one reference picture in the first collocated picture index list, and if so identifying the collocated picture from the first collocated picture index list with a collocated picture index syntax; if the flag is in a second state: providing a second reference picture set number that indicates a total number of reference pictures in the second collocated picture index list that are available for inter prediction of the current picture, and determining if the second reference picture set number indicates that there is more than one reference picture in the second collocated picture index list, and if so identifying the collocated picture from the second collocated picture index list with the collocated picture index syntax; and using the collocated picture to encode or decode the current picture. identifying a current picture in the video stream for encoding or decoding; identifying a collocated picture for inter prediction of the current picture, wherein identifying the collocated picture includes: indicating, depending on a state of a flag, whether the collocated picture can be located using a first collocated picture index list or a second collocated picture index list; if the flag is in a first state: providing a first reference picture set number that indicates a total number of reference pictures in the first collocated picture index list that are available for inter prediction of the current picture; and determining if the first reference picture set number indicates that there is more than one reference picture in the first collocated picture index list, and if so identifying the collocated picture from the first collocated picture index list with a collocated picture index syntax; if the flag is in a second state: providing a second reference picture set number that indicates a total number of reference pictures in the second collocated picture index list that are available for inter prediction of the current picture, and determining if the second reference picture set number indicates that there is more than one reference picture in the second collocated picture index list, and if so identifying the collocated picture from the second collocated picture index list with the collocated picture index syntax; and indicating, depending on a state of a flag, whether the collocated picture can be located using a first collocated picture index list or a second collocated picture index list; if the flag is in a first state: providing a first reference picture set number that indicates a total number of reference pictures in the first collocated picture index list that are available for inter prediction of the current picture; and determining if the first reference picture set number indicates that there is more than one reference picture in the first collocated picture index list, and if so identifying the collocated picture from the first collocated picture index list with a collocated picture index syntax; providing a first reference picture set number that indicates a total number of reference pictures in the first collocated picture index list that are available for inter prediction of the current picture; and determining if the first reference picture set number indicates that there is more than one reference picture in the first collocated picture index list, and if so identifying the collocated picture from the first collocated picture index list with a collocated picture index syntax; if the flag is in a second state: providing a second reference picture set number that indicates a total number of reference pictures in the second collocated picture index list that are available for inter prediction of the current picture, and determining if the second reference picture set number indicates that there is more than one reference picture in the second collocated picture index list, and if so identifying the collocated picture from the second collocated picture index list with the collocated picture index syntax; and providing a second reference picture set number that indicates a total number of reference pictures in the second collocated picture index list that are available for inter prediction of the current picture, and determining if the second reference picture set number indicates that there is more than one reference picture in the second collocated picture index list, and if so identifying the collocated picture from the second collocated picture index list with the collocated picture index syntax; and using the collocated picture to encode or decode the current picture.