Of itu-t sg16 wp3 and iso/iec jtc1/SC29/WG11

JCTVC-O0135 MV-HEVC/SHVC HLS: Carriage of auxiliary pictures [B. Choi, Y. Cho, M. W. Park, J. Y. Lee, H. Wey, C. Kim (Samsung)]

Discussed Wed 23rd evening (GJS).

The carriage methods of auxiliary pictures are studied and more specific syntax and constraints are proposed. First, the contribution proposes an indication method of auxiliary pictures with new NAL unit types, and discusses the pros and cons compared to the method specifying a new scalability dimension (proposed by Nokia in JCTVC-O0041). We suggest adopting one of them as a starting point and more specific syntax and constraints on top of that. The items of this contribution are listed below.

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  Carriage method of auxiliary pictures
  
  • 
    With new NAL unit type (proposed): Option-1
    
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    With new scalability dimension (Nokia, JCTVC-O0041): Option-2
    
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  Indication of auxiliary layers in VPS
  
  • 
    Indication of used auxiliary pictures for each layer : for Option-1
    
  • 
    Grouped signalling of layer dependencies : for Option-2
    
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  Constraints for Options 1&2
  
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  Modification of default_one_target_output_layer_flag : for Option-2
  

Regarding "group of layers" concept with grouped dependency structure – partly for bit efficiency and partly as a logical structuring of the data. The quantity of bit savings advantage is not so clear, and whether the dependency structure should be directly coupled may not be entirely clear.

It was asked whether the grouping concept is just a new interesting idea or is a way to solve a problem that we know we need to solve.

Regarding discussion of default_one_target_output_flag, it was remarked that this is somewhat of a way to distinguish between MVC style layering (in which all layers are output) and SHVC layering (in which only one) is output. It was remarked that this may not be the best indicator for combined layering approaches or other combination schemes of different layer types, such as alpha planes along with texture planes. However, it was noted that this flag is just to indicate default behaviour, and non-default indications can be signalled explicitly. It was remarked that O0109 is related.

Further discussed joint 3v+VC Wed 30th (GJS): In further discussion, the grouping concept was suggested to be primarily for convenience or bit savings rather than differing functionality or bug fixing, so this was deferred for further study. Decision: Relating to section #6, regarding auxiliary picture ID as part of the definition of the semantics of default_one_target_output_flag, adopt first variant.