udp-alsa单工语音传输，结果是——白花花的噪音

/* * server.c * *  Created on: Feb 5, 2016 *      Author: wing */#define fact 64#define ALSA_PCM_NEW_HW_PARAMS_API#include <alsa/asoundlib.h>#include <string.h>#include <netinet/in.h>#include <sys/socket.h>#include <arpa/inet.h>#include <sys/types.h>#include <stdio.h>int main(int argc,char *argv[]){/*创建socket*/int sockfd;struct sockaddr_in s_addr;if((sockfd=socket(AF_INET,SOCK_DGRAM,0))==-1){printf("%s","create sock failed!\n");return -1;}elseprintf("create sock success!\n");s_addr.sin_family=AF_INET;s_addr.sin_port=htons(7000);if(argc!=2){printf("用法：./voiceserver 客户端的IP地址.\n");return -1;}elses_addr.sin_addr.s_addr=inet_addr(argv[1]);bzero(&(s_addr.sin_zero),sizeof(s_addr.sin_zero));/*打开音频设备*/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;rc = snd_pcm_open(&handle, "default",SND_PCM_STREAM_CAPTURE,0);if (rc < 0){printf("unable to open pcm device: %s\n",snd_strerror(rc));return -1;}snd_pcm_hw_params_alloca(¶ms);snd_pcm_hw_params_any(handle, params);snd_pcm_hw_params_set_access(handle, params,SND_PCM_ACCESS_RW_INTERLEAVED);snd_pcm_hw_params_set_format(handle, params,SND_PCM_FORMAT_S16_LE);snd_pcm_hw_params_set_channels(handle, params, 2);val = 44100;snd_pcm_hw_params_set_rate_near(handle, params,&val, &dir);frames = 32;snd_pcm_hw_params_set_period_size_near(handle,params, &frames, &dir);rc = snd_pcm_hw_params(handle, params);if (rc < 0){printf("unable to set hw parameters: %s\n",snd_strerror(rc));return -1;}snd_pcm_hw_params_get_period_size(params,&frames, &dir);size = frames * 4*fact; /* 2 bytes/sample, 2 channels */buffer = (char *) malloc(size);while (1){rc = snd_pcm_readi(handle, buffer, frames);if (rc == -EPIPE){printf("overrun occurred\n");snd_pcm_prepare(handle);}elseif (rc < 0)printf("error from read: %s\n",snd_strerror(rc));elseif (rc != (int)frames)printf("short read, read %d frames\n", rc);sendto(sockfd,buffer,rc,0,(struct sockaddr *)&s_addr,sizeof(struct sockaddr));}snd_pcm_drain(handle);snd_pcm_close(handle);free(buffer);return 0;}

/* * client.c * *  Created on: Feb 5, 2016 *      Author: wing */#define fact 64#define ALSA_PCM_NEW_HW_PARAMS_API#include <alsa/asoundlib.h>#include <string.h>#include <netinet/in.h>#include <sys/socket.h>#include <arpa/inet.h>#include <sys/types.h>#include <stdio.h>int main(int argc,char *argv[]){int fd;int arg;int status;struct sockaddr_in s_addr;struct sockaddr_in c_addr;int sock;socklen_t addr_len;int len;if((sock=socket(AF_INET,SOCK_DGRAM,0))==-1){printf("create sock failed!\n");return -1;}elseprintf("create sock success.\n");memset(&s_addr,0,sizeof(struct sockaddr_in));s_addr.sin_family=AF_INET;s_addr.sin_port=htons(7000);s_addr.sin_addr.s_addr=INADDR_ANY;if((bind(sock,(struct sockaddr *)&s_addr,sizeof(s_addr)))==-1){printf("bind address to socket failed!\n");return -1;}elseprintf("bind address to socket success!\n");addr_len=sizeof(c_addr);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;rc = snd_pcm_open(&handle,"default",SND_PCM_STREAM_PLAYBACK,0);if (rc<0){printf("unable to open pcm device: %s\n",snd_strerror(rc));    return -1;}snd_pcm_hw_params_alloca(¶ms);snd_pcm_hw_params_any(handle, params);snd_pcm_hw_params_set_access(handle,params,SND_PCM_ACCESS_RW_INTERLEAVED);snd_pcm_hw_params_set_format(handle,params,SND_PCM_FORMAT_S16_LE);snd_pcm_hw_params_set_channels(handle,params, 2);val = 44100;snd_pcm_hw_params_set_rate_near(handle,params,&val,&dir);frames = 32;snd_pcm_hw_params_set_period_size_near(handle,params,&frames,&dir);rc = snd_pcm_hw_params(handle, params);if (rc<0){printf("unable to set hw parameters: %s\n",snd_strerror(rc));    return -1;}snd_pcm_hw_params_get_period_size(params,&frames,&dir);size = frames*4*fact; /* 2 bytes/sample, 2 channels */buffer = (char *) malloc(size);snd_pcm_hw_params_get_period_time(params,&val, &dir);while (1){recvfrom(sock,buffer,size,0,(struct sockaddr *)&c_addr,&addr_len);rc = snd_pcm_writei(handle, buffer, frames);if (rc == -EPIPE){printf("underrun occurred!\n");snd_pcm_prepare(handle);}elseif (rc < 0)printf("error from writei: %s\n",snd_strerror(rc));elseif (rc != (int)frames)printf("short write, write %d frames\n", rc);}snd_pcm_drain(handle);snd_pcm_close(handle);free(buffer);return 0;}