# audioPackFormat (Matrix)

The `audioPackFormat`

with `typeDefinition`

'Matrix' needs extra sub-elements to allow the definition of encoding (e.g. Left/Right to Mid/Side), decoding (e.g. Mid/Side to Left/Right) and direct (e.g. Lo/Ro) matrices.

The matrix can either be an encoding, a decoding or a direct matrix. An encoding matrix converts an input pack of any type (though “DirectSpeakers” would be the most likely to be used) into a matrix-encoded pack. A decoding matrix takes matrix-encoded pack and converts into a channel-based output pack. Related encoding and decoding matrices can be cross-referenced.

For example, Stereo to Mid/Side would be an encoding matrix, and Mid/Side to Stereo would be a decoding matrix.

The diagram below how encoder and decoder matrix `audioPackFormat`

s relate to each other, as well in the input and output `audioPackFormat`

s and `audioChannelFormat`

s.

The diagram below shows how a direct matrix `audioPackFormat`

relates to input and output `audioPackFormat`

s and `audioChannelFormat`

s.

## Attributes

There are no additional attributes defined for the `audioPackFormat`

with `typeDefinition`

'Matrix'. 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`

'Matrix'.

Even though it is defined as a common sub-element, the absoluteDistance sub-element is unlikely to be used in the 'Matrix' mode.

Sub-element | Description | Example | Quantity |
---|---|---|---|

audioChannelFormatIDRef | Reference to an audioChannelFormat | AC_00021001 | 0...* |

audioPackFormatIDRef | Reference to an audioPackFormat | AP_00021002 | 0...* |

absoluteDistance | Absolute distance in metres | 4.5 | 0 or 1 |

encodePackFormatIDRef | Reference to an encoding matrix audioPackFormat from a decoding matrix. | AP_00020001 | 0…* |

decodePackFormatIDRef | Reference to a decoding matrix audioPackFormat from an encoding matrix. | AP_00020101 | 0 …* |

inputPackFormatIDRef | Reference to a channel-based (DirectSpeakers) input audioPackFormat. | AP_00010002 | 0 or 1 |

outputPackFormatIDRef | Reference to a channel-based (DirectSpeakers) matrix decoded audioPackFormat. | AP_00010002 | 0 or 1 |

The encoding matrix contains an inputPackFormatIDRef, which references a channel-based input pack. It can also contain a list of decodePackFormatIDRefs, which are references to corresponding decoding matrices.

The decoding matrix contains an outputPackFormatIDRef, which reference a channel-based output pack. It can also contain a list of encodePackFormatIDRefs, which are references to corresponding encoding matrices.

The direct matrix contains an inputPackFormatIDRef, which references a channel-based input pack and an outputPackFormatIDRef, which reference a channel-based output pack.

## Example

<audioPackFormat audioPackFormatID="AP_00021001" audioPackFormatName="PackMat1_Encode" typeLabel="0002" typeDefinition="Matrix"> <audioChannelFormatIDRef>AC_00021001</audioChannelFormatIDRef> <audioChannelFormatIDRef>AC_00021002</audioChannelFormatIDRef> <decodePackFormatIDRef>AP_00021101</decodePackFormatIDRef> <inputPackFormatIDRef>AP_00010002</inputPackFormatIDRef> </audioPackFormat>