Audio Delta

Compute delta features

Since R2022b

• 

Libraries:
Audio Toolbox / Features

Description

The Audio Delta block computes the delta of the input audio features. The delta is an approximation of the first derivative of the audio features with respect to time.

Examples

Extract GTCC from Audio in Simulink

Extract gammatone cepstral coefficients and their delta features in Simulink^®.

• Open Model

Ports

Input

Port_1 — Audio features

scalar | vector | matrix | 3-D array

Audio features, specified as a scalar, vector, matrix, or 3-D array. The delta computation operates along the first dimension. All other dimensions are treated as independent channels.

Data Types: single | double

Output

Port_1 — Delta of audio features

scalar | vector | matrix | array

Delta of audio features, returned as an array that is the same size and data type as the input.

Data Types: single | double

Parameters

Delta window length — Window length over which to calculate delta

9 (default) | odd integer greater than 2

Window length over which to calculate delta, specified as an odd integer greater than 2.

Simulate using — Specify type of simulation to run

Interpreted execution (default) | Code generation

• Interpreted execution –– Simulate model using the MATLAB^® interpreter. This option shortens startup time but has a slower simulation speed than Code generation. In this mode, you can debug the source code of the block.

• Code generation –– Simulate model using generated C code. The first time you run a simulation, Simulink generates C code for the block. The C code is reused for subsequent simulations, as long as the model does not change. This option requires additional startup time, but the speed of the subsequent simulations is comparable to Interpreted execution.

Block Characteristics

Data Types	double | single
Direct Feedthrough	no
Multidimensional Signals	no
Variable-Size Signals	yes
Zero-Crossing Detection	no

More About

Delta of Audio Feature

The delta of an audio feature x is a least-squares approximation of the local slope of a region centered on sample x(k), which includes M samples before the current sample and M samples after the current sample.

$$delta=\frac{{\displaystyle \sum _{k=-M}^{M}kx(k)}}{{\displaystyle \sum _{k=-M}^M{k}^2}}$$

The delta window length defines the length of the region from –M to M.

For more information, see [1].

Algorithms

To support causal streaming, the Audio Delta block introduces a reporting delay of the least-squares approximation equal to floor(W/2), where W is the delta window length. For more information, see audioDelta.

References

[1] Rabiner, Lawrence R., and Ronald W. Schafer. Theory and Applications of Digital Speech Processing. Upper Saddle River, NJ: Pearson, 2010.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2022b