[Mp4-tech] Complementary Field Pairs

[Jagannathan, Shyam]

Dear Experts,
What qualifies a pair of fields as complementary field pairs?
The standard says,
3.1                 complementary field pair: A collective term for a
complementary reference field pair or a complementary non-reference
field pair.
3.2                 complementary non-reference field pair: Two
non-reference fields that are in consecutive access units in decoding
order as two coded fields of opposite parity where the first field is
not already a paired field.
3.3                 complementary reference field pair: Two reference
fields that are in consecutive access units in decoding order as two
coded fields and share the same value of the frame_num syntax element,
where the second field in decoding order is not an IDR picture and does
not include a memory_management_control_operation syntax element equal
to 5.
Let us assume a case where 2 non-reference field pairs appear in
decoding order as below,
    Frame num   :      7             7          
Decoding order  :| TF - BF - BF - TF |
If the BF picture access unit in the first pair is lost in a streaming
network (say),
    Frame num   :      7             7          
Decoding order  :| TF - X - BF - TF |
 the decoder will see TF belonging to first pair and BF belonging to
second pair and 'pair' them together as complementary non-reference
field pair as per standard definition.
This disturbs the correct decoding and hence display sequence.
Is my understanding correct? 
How should a decoder behave in such cases?
Is there a sure shot way of finding complementary field pairs?
Thanks and Regards,
Shyam
-------------- next part --------------
An HTML attachment was scrubbed...
URL: /pipermail/mp4-tech/attachments/20080206/c380122c/attachment.html