Here's a really simple program that captures audio for 5 seconds,
pauses, then captures 5 more seconds of audio, and finally plays it all
back (I used it to debug a problem with capture one time).
It worked on mint 13 linux laptop. Mint is like ubuntu 12.04
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <AL/al.h>
#include <AL/alc.h>
#include <sys/time.h>
#include <ctime>
int main(void)
{
const ALCchar * devices;
const ALCchar * ptr;
ALCdevice * mainDev;
ALCcontext * mainContext;
ALCdevice * captureDev;
ALubyte captureBuffer[1048576];
ALubyte *captureBufPtr;
ALint samplesAvailable;
ALint samplesCaptured;
time_t currentTime;
time_t lastTime;
ALuint buffer;
ALuint source;
ALint playState;
int i;
// Print the list of capture devices
printf("Available playback devices:\n");
devices = alcGetString(NULL, ALC_DEVICE_SPECIFIER);
ptr = devices;
//while (ptr[0] != NULL)
while (*ptr)
{
printf(" %s\n", ptr);
ptr += strlen(ptr) + 1;
}
// Open a playback device and create a context first
printf("Opening playback device:\n");
mainDev = alcOpenDevice(NULL);
if (mainDev == NULL)
{
printf("Unable to open playback device!\n");
exit(1);
}
devices = alcGetString(mainDev, ALC_DEVICE_SPECIFIER);
printf(" opened device '%s'\n", devices);
mainContext = alcCreateContext(mainDev, NULL);
if (mainContext == NULL)
{
printf("Unable to create playback context!\n");
exit(1);
}
printf(" created playback context\n");
// Make the playback context current
alcMakeContextCurrent(mainContext);
alcProcessContext(mainContext);
// Print the list of capture devices
printf("Available capture devices:\n");
devices = alcGetString(NULL, ALC_CAPTURE_DEVICE_SPECIFIER);
ptr = devices;
//while (ptr[0] != NULL)
while (*ptr)
{
printf(" %s\n", ptr);
ptr += strlen(ptr) + 1;
}
// Open the default device
printf("Opening capture device:\n");
captureDev = alcCaptureOpenDevice(NULL, 8000, AL_FORMAT_MONO16, 800);
if (captureDev == NULL)
{
printf(" Unable to open device!\n");
exit(1);
}
devices = alcGetString(captureDev, ALC_CAPTURE_DEVICE_SPECIFIER);
printf(" opened device %s\n", devices);
// Wait for three seconds to prompt the user
for (i = 3; i > 0; i--)
{
printf("Starting capture in %d...\r", i);
fflush(stdout);
lastTime = time(NULL);
currentTime = lastTime;
while (currentTime == lastTime)
{
currentTime = time(NULL);
usleep(100000);
}
}
printf("Starting capture NOW!\n");
fflush(stdout);
lastTime = currentTime;
// Capture (roughly) five seconds of audio
alcCaptureStart(captureDev);
samplesCaptured = 0;
captureBufPtr = captureBuffer;
while (currentTime < (lastTime + 5))
{
// Get the number of samples available
alcGetIntegerv(captureDev, ALC_CAPTURE_SAMPLES, 1, &samplesAvailable);
// Copy the samples to our capture buffer
if (samplesAvailable > 0)
{
alcCaptureSamples(captureDev, captureBufPtr, samplesAvailable);
samplesCaptured += samplesAvailable;
printf("Captured %d samples (adding %d)\r", samplesCaptured,
samplesAvailable);
fflush(stdout);
// Advance the buffer (two bytes per sample * number of samples)
captureBufPtr += samplesAvailable * 2;
}
// Wait for a bit
usleep(10000);
// Update the clock
currentTime = time(NULL);
}
printf("\nPausing capture.\n");
alcCaptureStop(captureDev);
// Wait for three seconds to prompt the user
for (i = 3; i > 0; i--)
{
printf("Resuming capture in %d...\r", i);
fflush(stdout);
lastTime = time(NULL);
currentTime = lastTime;
while (currentTime == lastTime)
{
currentTime = time(NULL);
usleep(100000);
}
}
printf("Resuming capture NOW!\n");
fflush(stdout);
lastTime = currentTime;
// Capture (roughly) five seconds of audio
alcCaptureStart(captureDev);
while (currentTime < (lastTime + 5))
{
// Get the number of samples available
alcGetIntegerv(captureDev, ALC_CAPTURE_SAMPLES, 1, &samplesAvailable);
// Copy the samples to our capture buffer
if (samplesAvailable > 0)
{
alcCaptureSamples(captureDev, captureBufPtr, samplesAvailable);
samplesCaptured += samplesAvailable;
printf("Captured %d samples (adding %d)\r", samplesCaptured,
samplesAvailable);
fflush(stdout);
// Advance the buffer (two bytes per sample * number of samples)
captureBufPtr += samplesAvailable * 2;
}
// Wait for a bit
usleep(10000);
// Update the clock
currentTime = time(NULL);
}
printf("\nDone capturing.\n");
alcCaptureStop(captureDev);
// Play back the captured data
printf("Starting playback...\n");
fflush(stdout);
// Generate an OpenAL buffer for the captured data
alGenBuffers(1, &buffer);
alGenSources(1, &source);
alBufferData(buffer, AL_FORMAT_MONO16, captureBuffer,samplesCaptured*2, 8000);
alSourcei(source, AL_BUFFER, buffer);
alSourcePlay(source);
// Wait for the source to stop playing
playState = AL_PLAYING;
while (playState == AL_PLAYING)
{
printf(" source %d is playing...\r", source);
fflush(stdout);
alGetSourcei(source, AL_SOURCE_STATE, &playState);
usleep(100000);
}
printf("\nDone with playback.\n");
fflush(stdout);
// Shut down OpenAL
alDeleteSources(1, &source);
alDeleteBuffers(1, &buffer);
alcMakeContextCurrent(NULL);
alcCloseDevice(mainDev);
alcCaptureCloseDevice(captureDev);
}
Compile with this:
g++ p.cpp -lalut -lopenal -o p
