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#include <tinyalsa/asoundlib.h> #include <stdio.h> #include <stdlib.h> #include <stdint.h> #include <signal.h> #include <string.h> #include <time.h>
#define ID_RIFF 0x46464952 #define ID_WAVE 0x45564157 #define ID_FMT 0x20746d66 #define ID_DATA 0x61746164
#define FORMAT_PCM 1
struct wav_header { uint32_t riff_id; uint32_t riff_sz; uint32_t riff_fmt; uint32_t fmt_id; uint32_t fmt_sz; uint16_t audio_format; uint16_t num_channels; uint32_t sample_rate; uint32_t byte_rate; uint16_t block_align; uint16_t bits_per_sample; uint32_t data_id; uint32_t data_sz; };
int capturing = 1;
unsigned int capture_sample(FILE *file, unsigned int card, unsigned int device, unsigned int channels, unsigned int rate, enum pcm_format format, unsigned int period_size, unsigned int period_count, unsigned int cap_time);
void sigint_handler(int sig __unused) { capturing = 0; }
int main(int argc, char **argv) { FILE *file; struct wav_header header; unsigned int card = 0; unsigned int device = 0; unsigned int channels = 2; unsigned int rate = 44100; unsigned int bits = 16; unsigned int frames; unsigned int period_size = 1024; unsigned int period_count = 4; unsigned int cap_time = 0; enum pcm_format format;
if (argc < 2) { fprintf(stderr, "Usage: %s file.wav [-D card] [-d device]" " [-c channels] [-r rate] [-b bits] [-p period_size]" " [-n n_periods] [-T capture time]\n", argv[0]); return 1; }
file = fopen(argv[1], "wb"); if (!file) { fprintf(stderr, "Unable to create file '%s'\n", argv[1]); return 1; }
argv += 2; while (*argv) { if (strcmp(*argv, "-d") == 0) { argv++; if (*argv) device = atoi(*argv); } else if (strcmp(*argv, "-c") == 0) { argv++; if (*argv) channels = atoi(*argv); } else if (strcmp(*argv, "-r") == 0) { argv++; if (*argv) rate = atoi(*argv); } else if (strcmp(*argv, "-b") == 0) { argv++; if (*argv) bits = atoi(*argv); } else if (strcmp(*argv, "-D") == 0) { argv++; if (*argv) card = atoi(*argv); } else if (strcmp(*argv, "-p") == 0) { argv++; if (*argv) period_size = atoi(*argv); } else if (strcmp(*argv, "-n") == 0) { argv++; if (*argv) period_count = atoi(*argv); } else if (strcmp(*argv, "-T") == 0) { argv++; if (*argv) cap_time = atoi(*argv); } if (*argv) argv++; }
header.riff_id = ID_RIFF; header.riff_sz = 0; header.riff_fmt = ID_WAVE; header.fmt_id = ID_FMT; header.fmt_sz = 16; header.audio_format = FORMAT_PCM; header.num_channels = channels; header.sample_rate = rate;
switch (bits) { case 32: format = PCM_FORMAT_S32_LE; break; case 24: format = PCM_FORMAT_S24_LE; break; case 16: format = PCM_FORMAT_S16_LE; break; default: fprintf(stderr, "%u bits is not supported.\n", bits); fclose(file); return 1; }
header.bits_per_sample = pcm_format_to_bits(format); header.byte_rate = (header.bits_per_sample / 8) * channels * rate; header.block_align = channels * (header.bits_per_sample / 8); header.data_id = ID_DATA;
fseek(file, sizeof(struct wav_header), SEEK_SET);
signal(SIGINT, sigint_handler); signal(SIGHUP, sigint_handler); signal(SIGTERM, sigint_handler); frames = capture_sample(file, card, device, header.num_channels, header.sample_rate, format, period_size, period_count, cap_time); printf("Captured %u frames\n", frames);
header.data_sz = frames * header.block_align; header.riff_sz = header.data_sz + sizeof(header) - 8; fseek(file, 0, SEEK_SET); fwrite(&header, sizeof(struct wav_header), 1, file);
fclose(file);
return 0; }
unsigned int capture_sample(FILE *file, unsigned int card, unsigned int device, unsigned int channels, unsigned int rate, enum pcm_format format, unsigned int period_size, unsigned int period_count, unsigned int cap_time) { struct pcm_config config; struct pcm *pcm; char *buffer; unsigned int size; unsigned int bytes_read = 0; unsigned int frames = 0; struct timespec end; struct timespec now;
memset(&config, 0, sizeof(config)); config.channels = channels; config.rate = rate; config.period_size = period_size; config.period_count = period_count; config.format = format; config.start_threshold = 0; config.stop_threshold = 0; config.silence_threshold = 0;
pcm = pcm_open(card, device, PCM_IN, &config); if (!pcm || !pcm_is_ready(pcm)) { fprintf(stderr, "Unable to open PCM device (%s)\n", pcm_get_error(pcm)); return 0; }
size = pcm_frames_to_bytes(pcm, pcm_get_buffer_size(pcm)); buffer = malloc(size); if (!buffer) { fprintf(stderr, "Unable to allocate %u bytes\n", size); free(buffer); pcm_close(pcm); return 0; }
printf("Capturing sample: %u ch, %u hz, %u bit\n", channels, rate, pcm_format_to_bits(format));
clock_gettime(CLOCK_MONOTONIC, &now); end.tv_sec = now.tv_sec + cap_time; end.tv_nsec = now.tv_nsec;
while (capturing && !pcm_read(pcm, buffer, size)) { if (fwrite(buffer, 1, size, file) != size) { fprintf(stderr,"Error capturing sample\n"); break; } bytes_read += size; if (cap_time) { clock_gettime(CLOCK_MONOTONIC, &now); if (now.tv_sec > end.tv_sec || (now.tv_sec == end.tv_sec && now.tv_nsec >= end.tv_nsec)) break; } }
frames = pcm_bytes_to_frames(pcm, bytes_read); free(buffer); pcm_close(pcm); return frames; }
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