AKSamplerDemo for iOS

This demo allows you to try out the new AKSampler instrument. Unlike the old "AKSampler", which was just a wrapper around the AUSampler Audio Unit built into macOS and iOS, the new one is built entirely from scratch.

Getting samples into the program

Note you must run the AKSamplerDemo program once on your iOS device to get it ready to work with samples. When you do this, it won't make any sound at all, because there are no samples.

The demo program supports iTunes File Sharing, so once you have installed it on your iOS device, you can use iTunes to copy samples into its Documents folder. See this Apple document for details.

Getting the demo samples

To use this demo, you will first need to have some samples to load. Start by downloading these ready-made samples. Unzip wherever you wish, and use iTunes File Sharing as described above, to copy the ROMPlayer Instruments* folder into the Documents area for AKSamplerDemo.

The demo samples are the same as the ones included in the AudioKit ROMPlayer code repo on GitHub. They have been compressed using WavPack, and a .sfz metadata file has been added, to specify key/velocity mapping and loop points.

Using your own samples

Preparing samples for any sampler instrument is a somewhat complex process. The basic steps are:

1. Acquire sample files, either by recording a hardware or software instrument yourself, or purchasing ready-made samples.
2. If necessary, edit the samples to your liking.
3. If applicable, identify loop-start and end points for each sample file. With commercial samples, this will usually have been done for you.
4. (Optional) Create a metadata file to define the mapping of MIDI note and velocity values to specific samples. Commercial samples typically include such metadata files, often in multiple formats.
5. Get files onto your iOS device where they will be accessible to the app. Using iTunes file sharing is one approach. Another is to embed the samples into your app's bundle (see below).

Working without a metadata file

Use of a metadata file is optional. Refer to function loadAndMapCompressedSampleFiles() in Conductor.swift to see how you can load individual sample files programmatically, with the necessary key- and velocity-mapping numbers expressed as parameter values the function calls.

If you want to work with uncompressed samples in standard formats such as .wav, .aif, .caf etc., you can call AKSampler's loadAKAudioFile() method, passing in an AKAudioFile object initialized with the URL for your file.

The code in loadAndMapCompressedSampleFiles() creates URLs in the app's Documents folder, but if you choose to embed samples into your app's bundle, you would instead use something like this:

let fileURL = Bundle.main.url(forResource:"mySampleFile", withExtension: "wav")

Creating a SFZ metadata file

AKSampler presently uses the open-standard SFZ format for metadata. The demo samples package includes a README with details about how the samples and .sfz metadata file were prepared, and a useful Python3 script to convert ESX24 metadata files (.esx files) to SFZ format.

Note that AKSampler's ability to parse .sfz files is very limited. It won't work on most .sfz files.

In a pinch, you can use a text editor to examine the demo .sfz files (they're just text) and modify them appropriately for your own samples.