/*This example reads from the default PCM deviceand writes to standard output for 5 seconds of data.*//* Use the newer ALSA API */#define ALSA_PCM_NEW_HW_PARAMS_API#include <alsa/asoundlib.h>/**************************************************************/#define ID_RIFF 0x46464952#define ID_WAVE 0x45564157#define ID_FMT 0x20746d66#define ID_DATA 0x61746164typedef unsigned long uint32_t;typedef unsigned short uint16_t;#define FORMAT_PCM 1static uint32_t totle_size = 0;struct wav_header { /* RIFF WAVE Chunk */ uint32_t riff_id; uint32_t riff_sz; uint32_t riff_fmt; /* Format Chunk */ uint32_t fmt_id; uint32_t fmt_sz; uint16_t audio_format; uint16_t num_channels; uint32_t sample_rate; uint32_t byte_rate; /* sample_rate * num_channels * bps / 8 */ uint16_t block_align; /* num_channels * bps / 8 */ uint16_t bits_per_sample; /* Data Chunk */ uint32_t data_id; uint32_t data_sz;}__attribute__((packed));static struct wav_header hdr;/**************************************************************/int playback_file(unsigned rate, uint16_t channels, int fd, uint32_t total_count){ int rc; int size; uint32_t left_size; snd_pcm_t *handle; snd_pcm_hw_params_t *params; int dir; snd_pcm_uframes_t frames; char *buffer; /* TODO */ /* Open PCM device for playbacking. */ rc = snd_pcm_open(&handle, "default", SND_PCM_STREAM_PLAYBACK, 0); 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, channels); /* 44100 bits/second sampling rate (CD quality) */ snd_pcm_hw_params_set_rate_near(handle, params, &rate, &dir); /* Set period size to 32 frames. */ frames = 32; snd_pcm_hw_params_set_period_size_near(handle, params, &frames, &dir); /* 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)); exit(1); } /* Use a buffer large enough to hold one period */ snd_pcm_hw_params_get_period_size(params, &frames, &dir); size = frames * 2 * channels; /* 2 bytes/sample(16bit), 2 channels */ buffer = (char *) malloc(size); // while (left_size > 0) { while (1) { rc = read(fd, buffer, size); totle_size += rc; /* totle data size */ left_size = total_count - totle_size; if (rc != size) fprintf(stderr, "short read: read %d bytes\n", rc); rc = snd_pcm_writei(handle, buffer, frames); if (rc == -EPIPE) { /* EPIPE means overrun */ fprintf(stderr, "overrun occurred\n"); snd_pcm_prepare(handle); } else if (rc < 0) { fprintf(stderr, "error from write: %s\n", snd_strerror(rc)); } else if (rc != (int)frames) { fprintf(stderr, "short write, write %d frames\n", rc); }if(left_size <= 0){lseek(fd, sizeof(hdr), SEEK_SET);totle_size = 0;printf("again \n");//read(fd, &hdr, sizeof(hdr));} } snd_pcm_drain(handle); snd_pcm_close(handle); free(buffer); return 0;}/**************************************************************/int play_wav(const char *fn){ unsigned rate, channels; int fd; fd = open(fn, O_RDONLY, 0777); if (fd < 0) { fprintf(stderr, "playback: cannot open '%s'\n", fn); return -1; } if (read(fd, &hdr, sizeof(hdr)) != sizeof(hdr)) { fprintf(stderr, "playback: cannot read header\n"); return -1; } fprintf(stderr,"playback: %d ch, %d hz, %d bit, %s, file_size %ld\n", hdr.num_channels, hdr.sample_rate, hdr.bits_per_sample, hdr.audio_format == FORMAT_PCM ? "PCM" : "unknown", hdr.data_sz); return playback_file(hdr.sample_rate, hdr.num_channels, fd, hdr.data_sz);}int main(int argc, char **argv){ if (argc != 2) { fprintf(stderr,"usage: playback <file>\n"); return -1; } return play_wav(argv[1]);}//编译之前安装一下apt-get install libasound2-dev 不然会报缺少alsa/asoundlib.h头文件
//编译加上参数 gcc plabback.c -o playback -lasound
