//linux下ALSA播放声音的源程序 //@note 编译的时候，使用到了asound 的lib 所以要添加-lasoud库 #include <stdio.h> /* Use the newer ALSA API */ #define ALSA_PCM_NEW_HW_PARAMS_API #include <alsa/asoundlib.h> int main() { long loops; int rc; int size; snd_pcm_t *handle; snd_pcm_hw_params_t *params; unsigned int val; int dir; snd_pcm_uframes_t frames; snd_pcm_uframes_t periodsize; char *buffer; FILE *fp = fopen("play.wav", "rb"); if(fp == NULL) return 0; fseek(fp, 100, SEEK_SET); /* Open PCM device for playback. */ rc = snd_pcm_open(&handle, "default", SND_PCM_STREAM_PLAYBACK, 0);//SND_PCM_NONBLOCK); if (rc < 0) { fprintf(stderr, "unable to open pcm device: %s\n", snd_strerror(rc)); exit(1); } /* Allocate a hardware parameters object. */ snd_pcm_hw_params_alloca(?ms); /* Fill it in with default values. */ snd_pcm_hw_params_any(handle, params); /* Set the desired hardware parameters. */ /* Interleaved mode */ snd_pcm_hw_params_set_access(handle, params, SND_PCM_ACCESS_RW_INTERLEAVED); /* Signed 16-bit little-endian format */ snd_pcm_hw_params_set_format(handle, params, SND_PCM_FORMAT_S16_LE); /* Two channels (stereo) */ snd_pcm_hw_params_set_channels(handle, params, 1); /* 44100 bits/second sampling rate (CD quality) */ val = 8000; snd_pcm_hw_params_set_rate_near(handle, params, &val, &dir); /* Set period size to 32 frames. */ frames = 32; periodsize = frames * 2; rc = snd_pcm_hw_params_set_buffer_size_near(handle, params, &periodsize); if (rc < 0) { printf("Unable to set buffer size %li : %s\n", frames * 2, snd_strerror(rc)); } periodsize /= 2; rc = snd_pcm_hw_params_set_period_size_near(handle, params, &periodsize, 0); if (rc < 0) { printf("Unable to set period size %li : %s\n", periodsize, snd_strerror(rc)); } /* Write the parameters to the driver */ rc = snd_pcm_hw_params(handle, params); if (rc < 0) { fprintf(stderr, "unable to set hw parameters: %s\n", snd_strerror(rc)); } /* Use a buffer large enough to hold one period */ snd_pcm_hw_params_get_period_size(params, &frames, &dir); size = frames * 2; /* 2 bytes/sample, 2 channels */ buffer = (char *) malloc(size); fprintf(stderr, "size = %d\n", size); /* We want to loop for 5 seconds */ //snd_pcm_hw_params_get_period_time(params, // &val, &dir); //snd_pcm_start(handle); while (1) { rc = fread(buffer, 1, size, fp); if(rc == 0) { fprintf(stderr, "end of file on input\n"); break; } else if (rc != size) { } while(rc = snd_pcm_writei(handle, buffer, frames)<0) { usleep(2000); if (rc == -EPIPE) { /* EPIPE means underrun */ fprintf(stderr, "underrun occurred\n"); snd_pcm_prepare(handle); } else if (rc < 0) { fprintf(stderr, "error from writei: %s\n", snd_strerror(rc)); } } //snd_pcm_drain(handle); //usleep(7000); //printf("#\n"); } snd_pcm_drain(handle); snd_pcm_close(handle); free(buffer); fclose(fp); return 0; } |
