bjoernf
671f503a41
Remove dependency on external raw audio file.\ Play manual square wave instead. Reviewed-on: #2 Co-authored-by: bjoernf <bjoern.foersterling@web.de> Co-committed-by: bjoernf <bjoern.foersterling@web.de>
118 lines
2.7 KiB
C
118 lines
2.7 KiB
C
#include "play_raw_audio.h"
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#include "time_utils.h"
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#include <errno.h>
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#include <fcntl.h>
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#include <pulse/error.h>
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#include <pulse/simple.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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// prototypes for static functions
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static int play_square_wave(float frequency, float duration);
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int play_manual_alarm() {
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int err = 0;
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for (int i = 0; i < 3; i++) {
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for (int i = 0; i < 2; i++) {
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err = play_square_wave(1000.0, 0.2);
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if (err != 0) {
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return err;
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}
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sleep_ms(200);
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}
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sleep_ms(500);
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}
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return 0;
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}
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// UNUSED
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// Playing a raw audio file has the downside of depending on a file.
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int play_raw_audio(char file_name[]) {
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int pa_error = 0;
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char content[1024] = "";
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int myfd = open(file_name, O_RDONLY);
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if (myfd == -1) {
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fprintf(stderr, "Failed to open audio file %s: %s.\n", file_name, strerror(errno));
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return 1;
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}
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pa_simple* simple = NULL;
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pa_sample_spec ss;
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ss.format = PA_SAMPLE_S16LE;
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ss.rate = 48000;
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ss.channels = 2;
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simple = pa_simple_new(NULL, "Audio Playback", PA_STREAM_PLAYBACK, NULL, "playback", &ss, NULL, NULL, &pa_error);
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int i = 0;
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while (read(myfd, content, sizeof(content))) {
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// skip the first 1024 bytes to not play the file header
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if (i != 0) {
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pa_simple_write(simple, content, sizeof(content), &pa_error);
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}
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i++;
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}
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pa_simple_drain(simple, NULL);
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pa_simple_free(simple);
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close(myfd);
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return 0;
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}
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// Output a tone with the audio frequency "frequency"
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// for "duration" number of seconds.
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// The sound signals are not sine waves but square waves.
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static int play_square_wave(float frequency, float duration) {
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const int sample_rate = 44100;
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const int channel_count = 2;
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size_t buffer_size = sample_rate * channel_count * duration;
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short buffer[buffer_size] = {};
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pa_simple *s;
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pa_sample_spec ss = {
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.format = PA_SAMPLE_S16LE,
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.rate = sample_rate,
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.channels = channel_count,
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};
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// number of identical consecutive elements
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// 5 would look like this:
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// [0,0,0,0,0,32768,32768,32768,32768,32768,0,...]
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int array_interval = sample_rate / frequency;
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bool square_peak = false;
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for (int i = 0; i < buffer_size; i++) {
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if (i % array_interval == 0) {
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// toggle the value (0 or the max value for a short)
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square_peak = !square_peak;
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}
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if (square_peak) {
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buffer[i] = SHRT_MAX;
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} else {
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buffer[i] = 0;
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}
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}
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if (!(s = pa_simple_new(NULL, NULL, PA_STREAM_PLAYBACK, NULL, "playback", &ss, NULL, NULL, &errno))) {
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fprintf(stderr, "pa_simple_new() failed: %s\n", pa_strerror(errno));
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return 1;
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}
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if (pa_simple_write(s, buffer, sizeof(buffer), NULL) < 0) {
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fprintf(stderr, "pa_simple_write() failed: %s\n", pa_strerror(errno));
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return 1;
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}
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pa_simple_drain(s, NULL);
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pa_simple_free(s);
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return 0;
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}
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