Device Description File

The device description file (DDF) describes all data structures of a target device and how to access them via xTP.

Usually this file is generated by SFD automatically, and is not visible to end user.

So this document is mainly for audio object developers. They have to implement the creation of the DDF inside of the audio algorithm toolbox (AAT).

<Identification>

Identification of the target device is optional. If at least <Product> exists, a message is sent to the target device to check if the target device matches the device description fil

<VirtualDevice>

VirtualDevice with index zero is always the NodeManager and is added automatically.

<Objects>

Objects can be defined in two ways:

• If an object is only used once, it can be defined directly in the Node Def tree.
• If an object is used several times, then an object Tmp should be defined and the object Tmp can be Incld by using an object Incl.

<Object>

<Object>

Each StateVariable that is defined in the object represents one row of the table. In addition to the Attrs and Elmts of an object Def, a TableObject Def has:

<Object>

This object converts Biquad parameters to Biquad coefficients.

<TargetValues>

A BiquadCoefficientsObject must have five TargetValues (order is fixed):

1. FIR0
2. FIR1
3. FIR2
4. IIR1
5. IIR2

<StateVariables>

A BiquadCoefficientsObject must have four fixed StateVariables and an optional StateVariable (order does not matter). Assignment of StateVariables is done by buddy type:

<StateVariables>

StateVariables can be defined in two ways:

• If a StateVariable is only used once, it can be defined directly within the object Def.
• If a StateVariable is used several times, then a StateVariable Tmp should be defined and the StateVariable Tmp should be Incld in a StateVariable.

StateVariable for continuous numerical values.

StateVariable for enumerated discrete values with an additional label per value.

<Value>

Values must have an ascending order!

StateVariable for filter types: Enumerated discrete values are mapped to a filter type.

FilterTypeSV must not be first StateVariable of a PEQ buddy group! Otherwise EQ filter control (Graph – Frequency / Gain) will not work.

<Value>

Values must have an ascending order!

StateVariable that Incls a data array of float values.

Name	Type	Def	Tmp	Description
Type	Attr	1	1	Possible value: FloatArraySV
<DataType>	Elmt	1	1	Possible value: Block
Size Infowas added with J + 1 release	Elmt	1	1	Number of array elements
<Min> Infowas misused until J release to define minimal length of array. From J + 1 onwards value range can be defined	Elmt	1	1	Minimum is only used for display purpose
<Max> Infowas misused until J release to define maximal length of array. From J + 1 onwards value range can be defined	Elmt	1	1	Maximum is only used for display purpose
<DefaultValue>	Elmt	0 .. 1	0 .. 1	Comma separated default values of the array. There is no need to specify all values of the array. e.g. ‘0,1,0,0’ or ‘0,-1,-0.5,0.3’

StateVariable that includes a data array of 16 bit float values.

Data type was added with N release.

StateVariable that includes a data array of 16-bit fixed-point values.

Name	Type	Def	Tmp	Description
Type	Attr	1	1	Possible value: FixedPoint16ArraySV
<DataType>	Elmt	1	1	Possible value: Block
Size Infowas added with J + 1 release	Elmt	1	1	Number of array elements
<Min> Infowas misused until J to define minimal length of array. From J + 1 onwards value range can be defined	Elmt	1	1	Minimum is only used for display purpose
<Max> Infowas misused until J to define maximal length of array. From J + 1 onwards value range can be defined	Elmt	1	1	Maximum is only used for display purpose
<DefaultValue> Infowas misused until J release to define default size of the array. From J + 1 onwards default values of the array can be defined	Elmt	0 .. 1	0 .. 1	Comma separated default values of the array. There is no need to specify all values of the array. e.g. ‘0,1,0,0’ or ‘0,-1,-0.5,0.3’

StateVariable that includes string values.

StateVariable that includes a data array of 16-bits, 24-bits or 32-bits fixed-point values.

Name	Type	Def	Tmp	Description
Type	Attr	1	1	Possible value: FixedPoint16ArraySV
<DataType>	Elmt	1	1	Possible value: Block
Size Infowas added with J + 1 release	Elmt	1	1	Number of array elements
<Min> Infowas misused until J to define minimal length of array. From J + 1 onwards value range can be defined	Elmt	1	1	Minimum is only used for display purpose
<Max> Infowas misused until J to define maximal length of array. From J + 1 onwards value range can be defined	Elmt	1	1	Maximum is only used for display purpose
<DefaultValue> Infowas misused until J release to define default size of the array. From J + 1 onwards default values of the array can be defined	Elmt	0 .. 1	0 .. 1	Comma separated default values of the array. There is no need to specify all values of the array. e.g. ‘0,1,0,0’ or ‘0,-1,-0.5,0.3’
<TargetValue>	Attr	NA	NA	TargetValue must use FixedPointBitConverter and specify format for M and N e.g. ‘ <TargetValue> <BitConverter DigitsBeforeDecimal=”8″                       DigitsAfterDecimal=”24″>FixedPointBitConverter</BitConverter> </TargetValue>’

 

A TargetValue is the link between a StateVariable and a memory block of the target device.

Legend:

Emphasized fields are only an example and can be adjusted.

<StateVariable Key=”CoefficientsHighTmp” Type=”FixedPoint16ArraySV”>

   <DataType>Block</DataType>

   <Size>3072</Size>

   <Min>-1</Min>

   <Max>1</Max>

   <DefaultValue>0</DefaultValue>

   <BuddyGroup>FIR</BuddyGroup>

   <BuddyType>Coefficients</BuddyType>

   <TargetValue>

      <BitConverter>UInt8ArrayBitConverter</BitConverter>

   </TargetValue>

</StateVariable>

<StateVariable Key=”StringTmp” Type=”StringSV”>

   <DataType>String</DataType>

   <DefaultValue>some Text</DefaultValue>

   <TargetValue Size=”32“>

      <BitConverter>StringBitConverter</BitConverter>

   </TargetValue>

</StateVariable>