# deltas

From tuneR v1.3.3
by Uwe Ligges

##### Calculate delta features

Calculate the deltas (derivatives) of a sequence of features using a w-point window with a simple linear slope.

##### Usage

`deltas(x, w = 9)`

##### Arguments

- x
Matrix of features. Every column represents one time frame. Each row is filtered separately.

- w
Window width (usually odd).

##### Details

This function mirrors the delta calculation performed in HTKs ‘feacalc’.

##### Value

Returns a matrix of the delta features (one column per frame).

##### References

Daniel P. W. Ellis: http://www.ee.columbia.edu/~dpwe/resources/matlab/rastamat/

##### Examples

```
# NOT RUN {
testsound <- normalize(sine(400) + sine(1000) + square(250), "16")
m <- melfcc(testsound, frames_in_rows=FALSE)
d <- deltas(m)
# }
```

*Documentation reproduced from package tuneR, version 1.3.3, License: GPL-2 | GPL-3*

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