Using Audio Files as Input Sources


This document describes how to use audio wave files as the source for audio processing functions.

Audio Files

Some of the functions in the AudioTools family of apps can take their input from audio wave files, rather than from real-time audio sources like the built-in mic. Functions that support this feature currently include RTA, FFT, Smaart Spectrum, SPL Pro, and SPL Graph.

Currently, only wave files using PCM format in either mono or stereo may be used for this feature.

Preparing an Audio File

This option looks in the SPL Graph public folder for its files. All audio wave files that are stored from the SPL Graph module will be available.

If you want to use your own wave file, just copy it into the SPL Graph public folder. There are different ways to do this, depending on your file storage method. Make sure that the file is a PCM encoded 16-bit wave file, recorded at 48k if possible. 44.1k will also work, but some functions in AudioTools expect the 48k sample rate. The files must have the ".wav" extension.

Using Internal Storage

Connect your iOS device to a browser, just as you would to download a file. Navigate to the SPL Graph public page, and use the Upload File button to transfer the file to the folder on the iOS device.

iCloud

Drop the wave file into the iCloud folder

studiosixdigital/public/SPL Graph

Dropbox

Dropbox is not currently supported for external wave files.

Selecting a File

Files are selected from the Input Sources page, which is accessed on the Setup page for the individual function, or from the Input button on the SPL Pro main page.

Tap the "Select Input File" button to bring up a list of available files. Any wave files saved from SPL Graph, and any wave files that you have manually placed into that folder will also be shown in the list.

Tap the row that shows the file that you wish to use, to highlight it. Then tap the "Select File" button to open the file and make it available to the function, such as FFT.

Audio File Navigation

On the main module screen, you will see a moving slider. This represents the relative current position in the audio file that is being processed. The file will be processed from the beginning to the end, and then the position will loop back to the beginning.

You can use the slider to change the current position in the file.

Going Back to Live Audio

To return to normal real-time audio processing, go back to the Input Sources page, and tap the Clear button in the toolbar. The functions will return to live audio  processing.

Re-selecting the Previous File

From the Input Sources page, tap the Reselect button in the toolbar. If a file was previously loaded, it will be re-loaded.