DVD 16:9 Letterbox Height in 4:3 Example
The use of 16:9 video for 4:3 displays with letterbox framing for DVD has the following values for the source and destination pictures.
The following rectangle values are used in the PictureSourceRect16thPel member of the DXVA_BlendCombination structure for the source picture:
top = 0
bottom = top + (16 X vertical_size) = 7680 or 9216
The following rectangle values are used in the PictureDestinationRect member of the DXVA_BlendCombination structure for the destination picture:
top = vertical_size / 8 = 60 or 72
bottom = 7 X vertical_size / 8 = 420 or 504