[Mp4-tech] [H.264] A question regarding frame_num

[Ye-Kui.Wang nokia.com]

Leaving field pictures out, a long-term reference picture may have the same frame_num value as a short-term reference picture, but two short-term reference pictures shall not share the same frame_num value. 
BR, YK
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	Sent: 2006$BG/(B1$B7n(B12$BF|(B 9:41
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	Subject: [Mp4-tech] [H.264] A question regarding frame_num
	Hi Experts,
	I had one question regarding the frame_num that is it possible the reference pictures in DPB have the same frame_num except for complementary reference field pairs ?
	For example, if there is a sequence IDR, P1, P2, P3, P4, P4, P6, P7, P8 with MaxFrameNum as 8, each are all reference frame, and each have frame_num has 0, 1, 2, 3, $B!D(B, 7, and 0. After P8 is decoded, it$B!G(Bs also inserted to DPB as a reference frame, then there would be 2 reference frame having fram_num as 0. If there is another picture P9 is to be decoded, Because IDR and P8 have the same frame_num, decoder would compute their PicNum as the same if P9 is a frame, and in this kind of case, if sliding window is to be applied to kick off one reference frame, which one should decoder choose ??
	Thanks in advance,
	Eric