The invention provide a video coder arranged to determine a video sequence in the one of the one or more picture of picture. the image size associated with the video sequence to align decoding unit can be a multiple of the size of the video sequence. In one example the video sequences of the coding unit size alignment may include a minimum coding unit size wherein the minimum coding unit size is selected from a plurality of minimum coding unit size corresponding to different pictures in the video sequence. the picture size of a video decoder configured to obtain syntax elements to determine the video sequence and the coding unit size alignment. the video decoder to the image size decoding included in the pictures in the video sequence and the decoded picture stored in the decoded picture buffer.

A video encoder is configured to determine a picture size for one or more pictures included in a video sequence. The picture size associated with the video sequence may be a multiple of an aligned coding unit size for the video sequence. In one example the aligned coding unit size for the video sequence may comprise a minimum coding unit size where the minimum coding unit size is selected from a plurality of smallest coding unit sizes corresponding to different pictures in the video sequence. A video decoder is configured to obtain syntax elements to determine the picture size and the aligned coding unit size for the video sequence. The video decoder decodes the pictures included in the video sequence with the picture size and stores the decoded pictures in a decoded picture buffer.