ALSA.rar_alsa_alsa 播放_linux alsa 录音

/* This program reads from the default PCM device and writes to standard output for 5 seconds of data. */ /* Use the newer ALSA API */ #define ALSA_PCM_NEW_HW_PARAMS_API #include <stdio.h> #include <stdlib.h> #include <alsa/asoundlib.h> #define LENGTH 3 //录音时间,秒 #define RATE 9600 //采样频率 #define SIZE 16 //量化位数 #define CHANNELS 1 //声道数目 #define RSIZE 8 //buf的大小， /********以下是wave格式文件的文件头格式说明******/ /*------------------------------------------------ | RIFF WAVE Chunk | | ID = 'RIFF' | | RiffType = 'WAVE' | ------------------------------------------------ | Format Chunk | | ID = 'fmt ' | ------------------------------------------------ | Fact Chunk(optional) | | ID = 'fact' | ------------------------------------------------ | Data Chunk | | ID = 'data' | ------------------------------------------------*/ /**********以上是wave文件格式头格式说明***********/ /*wave 文件一共有四个Chunk组成，其中第三个Chunk可以省略，每个Chunk有标示（ID）, 大小（size,就是本Chunk的内容部分长度）,内容三部分组成*/ struct fhead { /****RIFF WAVE CHUNK*/ unsigned char a[4];//四个字节存放'R','I','F','F' long int b; //整个文件的长度-8;每个Chunk的size字段，都是表示除了本Chunk的ID和SIZE字段外的长度; unsigned char c[4];//四个字节存放'W','A','V','E' /****RIFF WAVE CHUNK*/ /****Format CHUNK*/ unsigned char d[4];//四个字节存放'f','m','t','' long int e; //16后没有附加消息，18后有附加消息；一般为16，其他格式转来的话为18 short int f; //编码方式，一般为0x0001; short int g; //声道数目，1单声道，2双声道; long int h; //采样频率; long int i; //每秒所需字节数; short int j; //每个采样需要多少字节，若声道是双，则两个一起考虑; short int k; //即量化位数 /****Format CHUNK*/ /***Data Chunk**/ unsigned char p[4];//四个字节存放'd','a','t','a' long int q; //语音数据部分长度，不包括文件头的任何部分 }wavehead;//定义WAVE文件的文件头结构体 int startRecord(void) { 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; char *buffer; int fd_f; int status; /*以下wave 文件头赋值*/ wavehead.a[0]='R'; wavehead.a[1]='I'; wavehead.a[2]='F'; wavehead.a[3]='F'; wavehead.b=LENGTH*RATE*CHANNELS*SIZE/8-8; wavehead.c[0]='W'; wavehead.c[1]='A'; wavehead.c[2]='V'; wavehead.c[3]='E'; wavehead.d[0]='f'; wavehead.d[1]='m'; wavehead.d[2]='t'; wavehead.d[3]=' '; wavehead.e=16; wavehead.f=1; wavehead.g=CHANNELS; wavehead.h=RATE; wavehead.i=RATE*CHANNELS*SIZE/8; wavehead.j=CHANNELS*SIZE/8; wavehead.k=SIZE; wavehead.p[0]='d'; wavehead.p[1]='a'; wavehead.p[2]='t'; wavehead.p[3]='a'; wavehead.q=LENGTH*RATE*CHANNELS*SIZE/8; /*以上wave 文件头赋值*/ /* Open PCM device for recording (capture). */ rc = snd_pcm_open(&handle, "default", SND_PCM_STREAM_CAPTURE, 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(&params); /* 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) */ val = RATE; snd_pcm_hw_params_set_rate_near(handle, params, &val, &dir); /* Set period size to 32 frames. */ frames = 32; snd_pcm_hw_params_set_period_size_near(handle, params, &frames, &dir); //frames=55 /* Write the parameters to the driver */ rc = snd_pcm_hw_params(handle, params); //frames=55 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; /* 2 bytes/sample, 2 channels */ buffer = (char *) malloc(size); /* We want to loop for 5 seconds */ snd_pcm_hw_params_get_period_time(params, &val, &dir); loops = 5000000 / val; //val=5804 if(( fd_f = open("./sound.wav", O_CREAT|O_RDWR,0777))==-1)//创建一个wave格式语音文件 { perror("cannot creat the sound file"); } if((status = write(fd_f, &wavehead, sizeof(wavehead)))==-1)//写入wave文件的文件头 { perror("write to sound'head wrong!!"); } while (loops > 0) { //861 loops--; rc = snd_pcm_readi(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 read: %s\n", snd_strerror(rc)); } else if (rc != (int)frames) { //rc=frames=55 fprintf(stderr, "short read, read %d frames\n", rc); } // rc = write(1, buffer, size); //seek(fd_f,0L,SEEK_END); if(write(fd_f, buffer, size)==-1) //rc 不行 { perror("write to sound wrong!!"); } if (rc != size) fprintf(stderr, "short write: wrote %d bytes\n", rc); } snd_pcm_drain(handle); snd_pcm_close(handle); free(buffer); close(fd_f); return 0; } int main(int argc, char *argv[]) { startRecord(); return 0; }