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LameAudio

A 4-channel synthesizer for the LameStation.

audio : "LameAudio"

Demos for this object can be found in the /demos/audio/ folder of the SDK.

About

Initialization

Before LameAudio can be used, audio.Start must be called once and only once at the start of a program. LameAudio is designed so that only one synthesizer is ever running, and any object may call it.

Each channel has its own parameters that affect the sound it makes. audio.SetParam can control any parameter in the Channel parameter constant list. You can change all parameters at once with audio.LoadPatch, which is good if you change instruments often.

This is what a patch looks like.

DAT
    patch
    byte  $F, 127, 10, 100, 10, audio#_SAW

Each channel has a waveform and an envelope.

Waveform

The waveform generator is what actually creates the sound. Call audio.SetFrequency to play any frequency, or call audio.SetNote to play specific notes like on a piano.

Call audio.SetWaveform to load one of the following waveforms.

Value Name Waveform
0 Square
1 Sawtooth
2 Triangle
3 Sine
4 Noise
5 Sample

The Sample waveform is a 512B block of audio data, enough for one cycle. Call audio.SetSample with the address of a sample to load it. Only one sample can be used at a time.

A collection of ready-made samples can be found in the /media/samples/ folder of the SDK.

ADSR Envelope

The envelope controls the volume of the sound over time, allowing you to create sounds that hit sharply like bells, or have a long hold time like a wind instrument. You can control how it sounds with the ADSR parameters of the envelope.

ADSR stands for Attack, Decay, Sustain, and Release. You can configure ADSR settings with audio.SetADSR.

  • Attack (0-127) - The time from silence to full volume.

  • Decay (0-127) - The time from the max value to...

  • Sustain (0-127) - The volume at which the note is held while pressed.

  • Release (0-127) - The time from sustain to silence.

The envelope can be toggled with audio.SetEnvelope.

To silence all audio, use audio.StopAllSound.

Sample Format

LameStation songs consist of two main sections: pattern and sequence data.

Sample Data

A LameAudio sample is a 512-byte sequence of arbitrary data. It can be anything you want as long as its 512 bytes.

Example pattern section

DAT
wav_data

byte    <512 bytes...>

Since it's possible to use any address in memory, the running system can also create samples on the fly.

Sample Interface

The address of sample data can be passed directly to audio.SetSample, unless stored in another object. If so, use this interface:

PUB Addr
    return @wav_data

Functions

audio.LoadPatch

Load a new patch.

audio.LoadPatch(patchAddr)
  • address - The address of the new patch to load.

You can change all parameters at once with audio.LoadPatch. This is useful if you change instruments often.

A patch is formatted as follows:

byte    <attack>, <decay>, <sustain>, <release>, <waveform>

audio.PlaySound

Play sound on the specified channel.

audio.PlaySound(channel, note)
  • channel - The oscillator channel (0-3).

Note

This requires the envelope to be enabled.

audio.SetADSR

Set all parameters of the ADSR envelope shape.

audio.SetADSR(channel, attack, decay, sustain, release)

  • channel - The oscillator channel (0-3).

  • attack - Time from silence to full volume (0-127).

  • decay - Time from full volume to sustain (0-127).

  • sustain - The volume sustained while the note is held (0-127).

  • release - Time from note release to silence (0-127).

audio.SetEnvelope

Toggle the ADSR envelope on the given audio channel.

audio.SetEnvelope(channel, enabled)

  • channel - The oscillator channel (0-3).

  • enabled - True enables the envelope; false disables it.

The envelope can be toggled with audio.SetEnvelope.

audio.SetFrequency

Set the frequency increment of the given audio channel.

audio.SetFrequency(channel, value)

  • channel - The oscillator channel (0-3).

  • value - The new frequency increment to set (long).

This function controls the phase accumulator directly, allowing you to generate frequency possible with the synthesizer.

audio.SetNote

Set the note of the given audio channel.

audio.SetNote(channel, value)

  • channel - The oscillator channel (0-3).

  • value - The new note to set (0-127).

This function calculates and sets oscillator frequencies to musical note values.

audio.SetParam

Manually set a parameter of the audio channel.

audio.SetParam(channel, type, value)

  • channel - The oscillator channel (0-3).

  • type - _ATK, _DEC, _SUS, _REL, _WAV, _CONTROL.

  • value - Byte-sized value dependent on parameter (0-255).

audio.SetSample

Load a new sample.

audio.SetSample(address)
  • address - The address of the new sample to load.

The Sample waveform is a 512B block of audio data, enough for one cycle. Call audio.SetSample with the address of a sample to load it. Only one sample can be used at a time.

A collection of ready-made samples can be found in the /media/samples/ folder of the SDK.

audio.SetVolume

Set the volume of the given channel.

audio.SetVolume(channel, value)

  • channel - The oscillator channel (0-3).

  • value - The new volume for the channel.

audio.SetWaveform

Set the waveform of the given audio channel.

audio.SetWaveform(channel, value)

  • channel - The oscillator channel (0-3).

  • waveform - Index of waveform to use.

audio.Start

Initialize the LameAudio library.

audio.Start

audio.StartEnvelope

Trigger start of envelope on the specified channel.

audio.StartEnvelope(channel)
  • channel - The oscillator channel (0-3).

audio.StopAllSound

Immediately stop all sound on all channels.

audio.StopAllSound

audio.StopEnvelope

Trigger end of envelope on the specified channel.

audio.StopEnvelope(channel)
  • channel - The oscillator channel (0-3).

audio.StopSound

Stop sound on the specified channel.

audio.StopSound(channel)
  • channel - The oscillator channel (0-3).

Note

This function requires the envelope to be enabled.