AudioFileProcessor

The AudioFileProcessor plugin is used to play samples. It supports these formats: .wav, .ogg (Ogg Vorbis), .ds (DrumSynth files), .flac, .spx (Speex), .voc, .aif, .aiff, .au (Audacity BlockFile), .raw.

AudioFileProcessor

When different keys are hit, it can play the sample at different pitches by speeding up or slowing down the samples so their frequency changes. This also changes the apparent length of the sound and its characteristics, with the sound speeding up on higher pitches. Using the AudioFileProcessor with a single sample could produce unrealistic results with traditional instrument sounds if used over a wide range of notes. The basenote defines the key that will trigger the original sample sound. By default, the basenote is A4, and so playing the A4 key plays the original sample. The basenote can be changed by moving the small square through the horizontal length of black space over the instrument window's keyboard roll.

There are several playback controls.

• The Interpolation mode dropdown allows a choice for no interpolation (None), linear interpolation (Linear), and sinc interpolation (Sinc). The default choice is Linear.

Setting interpolation to None can cause odd sounds with samples of low sampling rate, and issues with playing the sample at lower pitches. It is not recommended. If you will be using a very high basenote, sinc may be a better option. At lower notes, less interpolation tends to cause sharper noises, so None interpolation may produce useful results with noisy percussive instruments.

• The folder icon (📂) allows you to choose the active sample from a file open dialog. You can also change the current sample by dragging a sample from the Side Bar and dropping it anywhere on the plugin tab of the instrument window.

• The Amplify knob (◢) (wide right-angled triangle) can be used for changing volume of playback of the audio file, in percentage of the original. 100% represents the original volume, 0% represents no sound, and 200% represents twice the volume of the original. A decrease in percentage below 100% decreases volume. However, this cannot correct clipping that was present in the original file.

• The Startpoint knob (|←) (with left-pointing arrow) and Endpoint knob (→|) (with right-pointing arrow) can be used if you only want to play back a specific part of a sample. They are connected to sliding markers that can move over the length of the sample. They are placed by default at the start and end of the sample respectively.

• The Loopback point knob (►|◄) (with a pair of inward-pointing arrows) points to a third positional marker other than the start and end playback markers that can be placed between the two. It is used in the loop modes explained below. It cannot exist beyond the start and end points, and so it can be "pushed" by moving the start or end points inwards with it. It is placed by default at the start of the sample.

• The Reverse sample (reversed R) controls the direction of playback. When enabled, the sample is reversed and played.

• The Continue sample playback across notes (with two horizontal bars and a little triangular marker above them) enables what acts like a stutter-mode. When enabled, sample playback is always started from the point in the sample where it last ended. By default, with this disabled, sample playback starts from the beginning at each new note. If this is enabled, you can reset the position back to the beginning during playback by playing a very low note, for example D0 or lower (if you haven't modified the basenote). Alternatively, playback position can be reset to the start by disabling this mode and enabling it again, and automation can be used to do this.

Restarting the sample can be triggered by playing a note that is more than 53 semitones (and 51 cents) below the basenote. For reference, if you are using the AudioFileProcessor with the default basenote of A4, any note below E0 will trigger the note to restart after it instead of continue, and no sound will play for the duration of the low note itself. If your instrument is detuned down by 52 or more cents, E0 will no longer trigger a note like this. The behaviour of these notes not playing audio only occurs in this mode. If low notes in AudioFileProcessor don't play any sound when you expect they should, check that this mode is disabled. This presumably happens because, on the assumption that the basenote represents a perfect A4 of 440 Hz, anything below 51 cents under E0 will be under 20 Hz, and so is outside the textbook range of human hearing.

The following three buttons make up the loop controls, and only one of them can be active at a time. The Disable loop mode is the one selected by default.

• Disable loop The power icon that is a circle with a vertical line through the top is for disabling loops.

• Enable loop: The icon with cyclic arrows forming a closed curve allows the sample to repeat from the loopback point once it reaches the end, if the note is still held down and playback has progressed all the way through the file. If the loopback point is at the start, then this behaves like a normal loop. In any case, it will play the section between the loopback point and the end on repeat till release.

• Enable ping-pong loop: The icon with a symmetrical triangle split vertically in half (◿◺) allows the audio sample to play back and forth between the end of the sample and the loopback point. When this mode is enabled, the sample will play normally and reach the end position of playback, at which point it will reverse playback to play backwards till the loopback point. Upon reaching the loopback point, it plays forward normally again till it reaches the end point, where it starts playing backwards again, and so on.