atempo

Adjust audio tempo.

The filter accepts exactly one parameter, the audio tempo. If not specified then the filter will assume nominal 1.0 tempo. Tempo must be in the [0.5, 100.0] range.

Note that tempo greater than 2 will skip some samples rather than blend them in. If for any reason this is a concern it is always possible to daisy-chain several instances of atempo to achieve the desired product tempo.

Command line examples

Slow down audio to 80% tempo:
```
atempo=0.8
```
To speed up audio to 300% tempo:
```
atempo=3
```
To speed up audio to 300% tempo by daisy-chaining two atempo instances:
```
atempo=sqrt(3),atempo=sqrt(3)
```