Utility function for playing audio on Linux or MacOS. More...

#include "wave_file_reader.h"
#include "tag.h"

Macros
#define	SAMPLE_RATE 44100

#define	AUDIO_BUFFER_SIZE 4410

#define	BUFFER_DURATION_NS 100000000LL

#define	NUM_CHANNELS 1

#define	MAX_AMPLITUDE 32765

#define	NUM_NOTES 8

Functions
void	lf_start_audio_loop (instant_t start_time)

void	lf_stop_audio_loop ()

int	lf_play_audio_waveform (lf_waveform_t *waveform, float emphasis, instant_t start_time)

Detailed Description

Utility function for playing audio on Linux or MacOS.

Author: Edward A. Lee; Soroush Bateni

Copyright: (c) 2020-2023, The University of California at Berkeley and UT Dallas. License in BSD 2-clause

Audio functions for Linux or MacOS. To start an audio loop, call lf_start_audio_loop(), passing it the logical time at which you would like the loop to start. To play a waveform, call lf_play_audio_waveform(). A waveform may be synthesized or read from a .wav file using read_wave_file() (see wave_file_reader.h).

To use this, include the following in your target properties:

 files: [
     "/lib/c/reactor-c/util/audio_loop_mac.c",
     "/lib/c/reactor-c/util/audio_loop.h",
     "/lib/c/reactor-c/util/audio_loop_linux.c",
 ],
 cmake-include: [
     "/lib/c/reactor-c/util/audio_loop.cmake"
 ]

In addition, you need this in your Lingua Franca file:

preamble {=
    #include "audio_loop.h"
=}

Macro Definition Documentation

◆ AUDIO_BUFFER_SIZE

#define AUDIO_BUFFER_SIZE 4410

◆ BUFFER_DURATION_NS

#define BUFFER_DURATION_NS 100000000LL

◆ MAX_AMPLITUDE

#define MAX_AMPLITUDE 32765

◆ NUM_CHANNELS

#define NUM_CHANNELS 1

◆ NUM_NOTES

#define NUM_NOTES 8

◆ SAMPLE_RATE

#define SAMPLE_RATE 44100

Function Documentation

◆ lf_play_audio_waveform()

int lf_play_audio_waveform	(	lf_waveform_t *	waveform,
		float	emphasis,
		instant_t	start_time )

Play the specified waveform with the specified emphasis at the specified time. If the waveform is null, play a simple tick (an impulse). If the waveform has length zero or volume 0, play nothing.

If the time is too far in the future (beyond the window of the current audio write buffer), then block until the audio output catches up. If the audio playback has already passed the specified point, then play the waveform as soon as possible and return 1. Otherwise, return 0.

Parameters

waveform	The waveform to play or NULL to just play a tick.
emphasis	The emphasis (0.0 for silence, 1.0 for waveform volume).
start_time	The time to start playing the waveform.

◆ lf_start_audio_loop()

void lf_start_audio_loop ( instant_t start_time )

Start an audio loop thread that becomes ready to receive audio amplitude samples via add_to_sound(). If there is already an audio loop running, then do nothing.

Parameters

start_time The logical time that aligns with the first audio buffer.

◆ lf_stop_audio_loop()

void lf_stop_audio_loop ( )

Stop the audio loop thread.

Macros

Functions