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Simple sound playback using ALSA API and libasound

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sound_playback.c
C
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/*
* Simple sound playback using ALSA API and libasound.
*
* Compile:
* $ cc -o play sound_playback.c -lasound
*
* Usage:
* $ ./play <sample_rate> <channels> <seconds> < <file>
*
* Examples:
* $ ./play 44100 2 5 < /dev/urandom
* $ ./play 22050 1 8 < /path/to/file.wav
*
* Copyright (C) 2009 Alessandro Ghedini <alessandro@ghedini.me>
* --------------------------------------------------------------
* "THE BEER-WARE LICENSE" (Revision 42):
* Alessandro Ghedini wrote this file. As long as you retain this
* notice you can do whatever you want with this stuff. If we
* meet some day, and you think this stuff is worth it, you can
* buy me a beer in return.
* --------------------------------------------------------------
*/
 
#include <alsa/asoundlib.h>
#include <stdio.h>
 
#define PCM_DEVICE "default"
 
int main(int argc, char **argv) {
unsigned int pcm, tmp, dir;
int rate, channels, seconds;
snd_pcm_t *pcm_handle;
snd_pcm_hw_params_t *params;
snd_pcm_uframes_t frames;
char *buff;
int buff_size, loops;
 
if (argc < 4) {
printf("Usage: %s <sample_rate> <channels> <seconds>\n",
argv[0]);
return -1;
}
 
rate = atoi(argv[1]);
channels = atoi(argv[2]);
seconds = atoi(argv[3]);
 
/* Open the PCM device in playback mode */
if (pcm = snd_pcm_open(&pcm_handle, PCM_DEVICE,
SND_PCM_STREAM_PLAYBACK, 0) < 0)
printf("ERROR: Can't open \"%s\" PCM device. %s\n",
PCM_DEVICE, snd_strerror(pcm));
 
/* Allocate parameters object and fill it with default values*/
snd_pcm_hw_params_alloca(&params);
 
snd_pcm_hw_params_any(pcm_handle, params);
 
/* Set parameters */
if (pcm = snd_pcm_hw_params_set_access(pcm_handle, params,
SND_PCM_ACCESS_RW_INTERLEAVED) < 0)
printf("ERROR: Can't set interleaved mode. %s\n", snd_strerror(pcm));
 
if (pcm = snd_pcm_hw_params_set_format(pcm_handle, params,
SND_PCM_FORMAT_S16_LE) < 0)
printf("ERROR: Can't set format. %s\n", snd_strerror(pcm));
 
if (pcm = snd_pcm_hw_params_set_channels(pcm_handle, params, channels) < 0)
printf("ERROR: Can't set channels number. %s\n", snd_strerror(pcm));
 
if (pcm = snd_pcm_hw_params_set_rate_near(pcm_handle, params, &rate, 0) < 0)
printf("ERROR: Can't set rate. %s\n", snd_strerror(pcm));
 
/* Write parameters */
if (pcm = snd_pcm_hw_params(pcm_handle, params) < 0)
printf("ERROR: Can't set harware parameters. %s\n", snd_strerror(pcm));
 
/* Resume information */
printf("PCM name: '%s'\n", snd_pcm_name(pcm_handle));
 
printf("PCM state: %s\n", snd_pcm_state_name(snd_pcm_state(pcm_handle)));
 
snd_pcm_hw_params_get_channels(params, &tmp);
printf("channels: %i ", tmp);
 
if (tmp == 1)
printf("(mono)\n");
else if (tmp == 2)
printf("(stereo)\n");
 
snd_pcm_hw_params_get_rate(params, &tmp, 0);
printf("rate: %d bps\n", tmp);
 
printf("seconds: %d\n", seconds);
 
/* Allocate buffer to hold single period */
snd_pcm_hw_params_get_period_size(params, &frames, 0);
 
buff_size = frames * channels * 2 /* 2 -> sample size */;
buff = (char *) malloc(buff_size);
 
snd_pcm_hw_params_get_period_time(params, &tmp, NULL);
 
for (loops = (seconds * 1000000) / tmp; loops > 0; loops--) {
 
if (pcm = read(0, buff, buff_size) == 0) {
printf("Early end of file.\n");
return 0;
}
 
if (pcm = snd_pcm_writei(pcm_handle, buff, frames) == -EPIPE) {
printf("XRUN.\n");
snd_pcm_prepare(pcm_handle);
} else if (pcm < 0) {
printf("ERROR. Can't write to PCM device. %s\n", snd_strerror(pcm));
}
 
}
 
snd_pcm_drain(pcm_handle);
snd_pcm_close(pcm_handle);
free(buff);
 
return 0;
}

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