[M4IF Technotes] interlaced content in MPEG-4

[Gaurav Aggarwal]

Hi all,
Is it true that in MPEG-4 either all VOP will be progressive or all
interlaced? MPEG-2 had two syntactic entities: progressive_sequence
and progressive_frame. There it is possible to have a sequence where
prog_seq=0 but still get pictures with prog_frame=1. 
In MPEG-4, there appears to be a single entity called "interlaced"
at video_object_layer. Now, this VOL is similar to a sequence, and
there is no interlaced/prog flag at the VOP layer. Is it correct to
say that either all pictures are progressive or all are interlaced?
Also, doesn't MPEG-4 support Pan Scan? It appears that there are no
display sizes. Only source sizes coded as video_object_layer_width
and video_objet_layer_height. Is it true that the stream doesn't
have the panning capabilities that MPEG-2 video had?
Thanks,
Gaurav
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