audioPackFormat (HOA)

The audioPackFormat with typeDefinition 'HOA' is used for scene-based audio (such as Higher Order Ambisonics). Many audioPackFormat definitions with the 'HOA' type are already defined in the Common Definitions, so they do not need to be defined explicitly when generating ADM metadata.

It is common that a pack of HOA components/signals will share the same normalization, NFC compensation and/or screen-relation. However, when the parameters are specified within an audioBlockFormat, these values overwrite those given in the audioPackFormat.

Attributes

There are no additional attributes defined for the audioPackFormat with typeDefinition 'HOA'. See Common Attributes for the list of common ones.

Sub-elements

In addition to the common sub-elements the following sub-elements are defined for the audioPackFormat with typeDefinition 'HOA'.

Sub-element	Description	Example	Quantity	Default
audioChannelFormatIDRef	Reference to an audioChannelFormat	AC_00040001	0...*	-
audioPackFormatIDRef	Reference to an audioPackFormat	AP_00040002	0...*	-
absoluteDistance	Absolute distance in metres	4.5	0 or 1	-
normalization	Indicates the normalization scheme of the HOA content (N3D, SN3D, FuMa).	N3D	0 or 1	SN3D
nfcRefDist	Indicates the reference distance (in metres) of the loudspeaker setup for near-field compensation (NFC). If no nfcRefDist is defined or the value is 0, NFC is not necessary.	2	0 or 1	0
screenRef	Indicates whether the content is screen-related (flag is equal to 1) or not (flag is equal to 0)	0	0 or 1	0

Example

<audioPackFormat audioPackFormatID="AP_00040001"
                 audioPackFormatName="3D_order1_SN3D_ACN"
                 typeLabel="0004" typeDefinition="HOA">
  <audioChannelFormatIDRef>AC_00040001</audioChannelFormatIDRef>
  <audioChannelFormatIDRef>AC_00040002</audioChannelFormatIDRef>
  <audioChannelFormatIDRef>AC_00040003</audioChannelFormatIDRef>
  <audioChannelFormatIDRef>AC_00040004</audioChannelFormatIDRef>
</audioPackFormat>