[M4IF Technotes] Interpretation of vop_coded

[Yogendra Kumar Gupta]

Dear All,
Can anyone please explain the interpretation of the flag vop_coded (when
vop_coded = 0) when video_object_layer_shape == RECTANGULAR. The standard
gives details of the construction of reconstructed frame but does not give
any interpretation regarding the construction of the current frame (that
would be used for display). The Microsoft reference code puts a grey image
of colour 128 in the o/p which doesn't look very nice in between while
watching a video. One of the conformance bitstreams contains frames where
every alternate frame the flag vop_coded is set to 0 and the o/p looks like
a blinking one where you get a decoded image and a gray image alternatively.
Could a better solution be use the previous frame itself for display when
vop_coded = 0. Also I would like to know when the flag vop_coded needs to be
set to 0 on the encoding side.
Regards
Yogender Kumar Gupta