A video coding device comprising: lower-layer coding means for coding a video sequence at a lower frame rate; upper-layer coding means for coding one or more specified part-areas of the video sequence at a higher frame rate; and synthesizing means for synthesizing a video sequence of the upper-layer with a video sequence of the lower-layer by using part-area-information representing the specified part-area; characterized in that the synthesizing means generates a lower-layer frame for synthesizable frame in absence of the lower-layer frame corresponding to the temporal position of the synthesizable frame in order to fill the absence, by using the lower-layer frame existing temporally before the synthesizable frame and a second part-area-information of a lower-layer frame existing temporally after the synthesizable frame, and by using the lower-layer frame existing temporally after synthesizable frame for a portion of only the first part-area, and by using the lower-layer frame existing temporally before the synthesizable frame for a portion of only the second part-area. A corresponding decoding device is also provided.