Split this report from #105

Can you add more detail here, e.g. where exactly in the code the problem is? Or maybe suggest a patch?

For MV-HEVC we are constrained to two views, but in general I would prefer to keep the implementation open to potential new profiles. But the issue may also affect 3D-HEVC?

1. In HEVC MV-HEVC Spec, there isn't identicalMotion Codition check description found. I think this code implementation in HTM are used to save read data bandwidth in non-MV-HEVC mode, Because if this condition is correct, the L0 and L1 would be same and 1/2 average used for combination, so that the result would be same as L0 only. However, for MV-HEVC, L0 and L1 may come from the different view picture of the same POC, so the simplify process may have some issue. Anyway, they need your double confirm and clarify??

2. Are MV-HEVC constrained to 2-views, Actually, in comformance streams, we found that 3-views sreams exists.

3. I think the issue may also affect 3D-HEVC. But need you to double confirm item#1.

I think you are right.
The Identical motion checks whether the two reference pictures and MVs are identical or not. And the current HTM uses only POC to check the identicality of the pictures.
But as you point out, the 3D picture has two dimensions, POC and View. So in my understanding, we should check "ViewId" (or ViewOrderId ) as well as "POC" in HTM (Another way is by checking "layer id").

A patch is attached. We may use MVHEVCS_H.bit (IBP structure) for check (please #define NH_MV_FIX_TICKET_105 0 for the test. It can be seen disbling identical motion check changes the decoding picture of layer2 (MVHEVCS_H_2) )

By the way, Multiview main profile supports more than 2 views (up to 62 views or something). The plan of Multiview stereo profile had been removed thanks to
per layer profile/level signalling.

Note: it seems the issue may exist in SHM as well.

Thanks for the patch. It seems to be fine for MV-HEVC. However, for 3D-HEVC the #elif branch is never reached, since NH_MV is always equal to 1 when NH_3D_ARP is equal to 1. A modified fix will be included in HTM-15.1.

If that, does MV-HEVC conformance streams of 3 views also need to referesh, is that right??

Thanks for ARP case fix.

And regarding comformance streams, this issue seems only affect MVHEVCS_H (3 views with IBP structure). But in my understanding, other streams also need to refresh due to other issues (especially TICKET100, OLS constraint for 2 layers, and PTL for non-additional OLS).

Do you have any plan when we will refresh the conformance MV-HEVC streams? So that we can double check them.