microphone.c File Reference

Microphone module implementation. More...

#include <sndfile.h>
#include <sys/syslog.h>
#include <sys/wait.h>
#include "../inc/microphone.h"

Include dependency graph for microphone.c:

Go to the source code of this file.

Macros
#define	THRESHOLD   -35
#define	LIMIT   3

Functions
int	startRecording ()
	Records a 2 second .wav audio from microphone. More...
double	calculateLoudness ()
	Calculates loudness of the .wav file. More...
int	processAudio (double *loudness)
	Processes the audio to check whether the baby is crying. More...

Detailed Description

Microphone module implementation.

Author

José Carvalho, João Carneiro

Date

2022-01-13

Copyright

Copyright (c) 2022

Definition in file microphone.c.

Macro Definition Documentation

LIMIT

#define LIMIT   3

Definition at line 16 of file microphone.c.

THRESHOLD

#define THRESHOLD   -35

Definition at line 15 of file microphone.c.

Function Documentation

calculateLoudness()

double calculateLoudness

(

)

Calculates loudness of the .wav file.

The value returned is expressed in the decibel (dB) scale being -1 the maximum value.

Returns

double (dB)

Definition at line 41 of file microphone.c.

processAudio()

int processAudio

(

double *

loudness

)

Processes the audio to check whether the baby is crying.

The loudness of the audio samples is calculated and, if the predefined threshold is passed, a counter is incremented. At 3 consecutive samples that have breached the threshold, it is considered that the baby is crying.

Returns

int

Definition at line 73 of file microphone.c.

startRecording()

int startRecording

(

)

Records a 2 second .wav audio from microphone.

Recording is possible by using FFmpeg. The parameters used are: -f alsa : force audio input device to be of ALSA -ac 1 : set audio channel to 1 -ar 44100 : set audio sampling rate to 44100 Hz -i plughw:0,0 : select the audio card referencing the microphone -c:a copy : set audio codec to copy (copies the frames directly instead of decoding/filtering/encoding) -t 2 : recording duration -y : overwrite output files audiorecord.wav output file

Returns

int

Definition at line 18 of file microphone.c.