==== hierarchy_descriptor

Defined by MPEG in <<ISO-13818-1>>.

[source,xml]
----
<hierarchy_descriptor
    no_view_scalability_flag="bool, default=true"
    no_temporal_scalability="bool, default=true"
    no_spatial_scalability="bool, default=true"
    no_quality_scalability="bool, default=true"
    hierarchy_type="uint4, required"
    hierarchy_layer_index="uint6, required"
    tref_present="bool, required"
    hierarchy_embedded_layer_index="uint6, required"
    hierarchy_channel="uint6, required"/>
----
