Linux ALSA音频库(二) 环境测试+音频合成+语音切换 项目代码分享

 

1. 环境测试

alsa_test.c

#include <alsa/asoundlib.h>
#include <stdio.h>

//  官方测试代码, 运行后只要有一堆信息打印出来,即说明安装成功了。

int main() 
{
    int val;
 
    printf("ALSA library version: %s\n",
                       SND_LIB_VERSION_STR);
 
    printf("\nPCM stream types:\n");
    for (val = 0; val <= SND_PCM_STREAM_LAST; val++)
            printf(" %s\n",
                  snd_pcm_stream_name((snd_pcm_stream_t)val));
 
    printf("\nPCM access types:\n");
    for (val = 0; val <= SND_PCM_ACCESS_LAST; val++)
    {
            printf(" %s\n",
                  snd_pcm_access_name((snd_pcm_access_t)val));
    }
 
    printf("\nPCM formats:\n");
    for (val = 0; val <= SND_PCM_FORMAT_LAST; val++)
        {
        if (snd_pcm_format_name((snd_pcm_format_t)val)!= NULL)
        {
            printf(" %s (%s)\n",
                    snd_pcm_format_name((snd_pcm_format_t)val),
                    snd_pcm_format_description(
                            (snd_pcm_format_t)val));
        }
    }
 
    printf("\nPCM subformats:\n");
    for (val = 0; val <= SND_PCM_SUBFORMAT_LAST;val++)
    {
            printf(" %s (%s)\n",
                  snd_pcm_subformat_name((
                snd_pcm_subformat_t)val),
                  snd_pcm_subformat_description((
                snd_pcm_subformat_t)val));
    }
 
    printf("\nPCM states:\n");
    for (val = 0; val <= SND_PCM_STATE_LAST; val++)
            printf(" %s\n",
                   snd_pcm_state_name((snd_pcm_state_t)val));
 
    return 0;
}

makefile:

.PHONY : rebuild clean


CC:= mips-linux-gnu-gcc
TARGET:= alsa_test.out


OBJS:= alsa_test.o 

INCLUDE += -I/usr/local/open_lib/include

LIBS += -lpthread -L/usr/local/open_lib/lib -lasound


$(TARGET) :$(OBJS)
    $(CC) $(LIBS) $^ -o [email protected] 


$(OBJS):%.o:%.c
    $(CC) $(INCLUDE) -c $^ -o [email protected]
    echo $(OBJS)


clean:
    $(RM) $(OBJS)
    $(RM) $(TARGET)
    @echo "clean"

rebuild : clean $(TARGET)
    @echo "rebuild"
官方测试代码, 运行后只要有一堆信息打印出来,即说明安装成功了。

 

2. 音频合成+语音切换 功能使用,单线程,不考虑多线程场景。

alsa_test.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <alsa/asoundlib.h>
#include <pthread.h>
#include <unistd.h>
#include <sys/time.h>
static char * name;
struct wav_header
{
char rld[4]; //riff 标志符号
int rLen; 
char wld[4]; //格式类型(wave)
char fld[4]; //"fmt"
int fLen; //sizeof(wave format matex)
short wFormatTag; //编码格式
short wChannels; //声道数
int nSamplesPersec ; //采样频率
int nAvgBitsPerSample;//WAVE文件采样大小
short wBlockAlign; //块对齐
short wBitsPerSample; //WAVE文件采样大小
char dld[4]; //”data“
int wSampleLength; //音频数据的大小

} wav_header, wav_header1, wav_header2, wav_header3;
static pthread_mutex_t mutex;   // 等待停止
static pthread_mutex_t mutex_play;  // 开启播放
snd_pcm_t* handle; //PCI设备句柄
static char * path1;
static char * path2;
static pthread_t id;
static char g_stop=0;
static int lock = 0;
int set_pcm_play(const char* path1, const char* path2, const char* path3);
int wait_stop_play(void);
/****   立即关闭播放的方法  ****
if(handle!=NULL)
{
g_stop=1;
snd_pcm_drop(handle);
}    
****    ****/
#if 0
int main(void)
{
system("stty -icanon");
handle = NULL;    
set_pcm_play("/etc/door_sound/201.wav", "/etc/door_sound/203.wav", "/etc/door_sound/201.wav");
printf("-----OVER11111111111111----\n\n");
set_pcm_play("/etc/door_sound/201.wav", NULL, NULL);
set_pcm_play("/etc/door_sound/203.wav", NULL, NULL);
set_pcm_play("/etc/door_sound/201.wav", NULL, NULL);
printf("-----OVER222222222222-------\n\n");
sleep(3);
#if 0  // 存在的问题:set_pcm_play两句话, 前面一句话叫得很快 , 后面正常  
set_pcm_play("/etc/door_sound/201.wav", "/etc/door_sound/203.wav", NULL);
set_pcm_play("/etc/door_sound/201.wav", "/etc/door_sound/203.wav", NULL);
set_pcm_play(NULL, NULL, "/etc/door_sound/203.wav"); // 这句话没有播放
printf("-----OVER333333333333-------\n\n");
#else
set_pcm_play("/etc/door_sound/201.wav", "/etc/door_sound/203.wav", NULL);
set_pcm_play("/etc/door_sound/201.wav", "/etc/door_sound/203.wav", NULL);
set_pcm_play("/etc/door_sound/203.wav", NULL, NULL);
printf("-----OVER333333333333-------\n\n");
#endif
//set_pcm_play("/TG/sound/333.wav", "/TG/sound/333.wav", "/TG/sound/333.wav");
// set_pcm_play("/TG/sound/1.wav", NULL, NULL);
return 0;
}
#else
pthread_t Handle_stop_sound_thread;
void *stop_sound_thread(void *arg)
{
sleep(2);
if(handle!=NULL)
{
printf("即将关闭当前语音流A \n");
g_stop=1; 
// snd_pcm_drop(handle); 不要立即关停。  因为这会导致当前正在执行snd_pcm_writei()写入出错。置位一个标志g_stop已经足够。
    }    
return NULL;
}
/*  ALSA使用教程 
**  Demo演示 
**  LMW  
**  2020 - 07 -xx
**使用了下alsa实现各语音提取合并(语音流A最多由三个wav文件合成) 、以及切换语音播报(关闭当前语音流A转而播报语音流B这样)、
**
**/
int main(void)
{
system("stty -icanon");
handle = NULL;    
//这里新建个线程,延时2秒后关闭当前的语音播放
if(pthread_create(&Handle_stop_sound_thread, NULL, stop_sound_thread, NULL))
{
perror("Create stop_sound_thread Err ");
}
else
{
pthread_detach(Handle_stop_sound_thread);
}
//这里搞个远大于2秒的语音播报
printf("-准备播报语音流A..\n");
set_pcm_play("/etc/door_sound/254.wav", "/etc/door_sound/203.wav", "/etc/door_sound/201.wav");
printf("-已关闭(中止)当前语音流A!\n\n");
//sleep(3);
printf("-准备播报语音流B..\n");
set_pcm_play("/etc/door_sound/254.wav", "/etc/door_sound/203.wav", "/etc/door_sound/201.wav");
printf("-语音流B顺利执行完毕!\n\n");
//sleep(3);
printf("-准备播报语音流C..\n");
set_pcm_play("/etc/door_sound/254.wav", "/etc/door_sound/254.wav", "/etc/door_sound/254.wav");
printf("-语音流C顺利执行完毕!\n\n");
return 0;
}
#endif
int para_common_set(int channels, int frequency, \
int bit, int datablock, snd_pcm_uframes_t *pframes)
{
int size = 0, dir=0;;
snd_pcm_hw_params_t* params;   //硬件信息和PCM流配置
unsigned int val;
int ret;
// 如果要做多线程处理,这里应该维护一个计数器cnt,使用mutex来保护该计数器
// 打开音频设备时,只有第一次打开才执行snd_pcm_open,以后则只是cnt++
// 同理,关闭设备时,执行计数器--操作,直到计数器减为0,才执行snd_pcm_close真正将设备关闭
//因为我的程序并不涉及多线程操作音频设备,所以不做上述处理
//单线程处理,这样够了:使用lock,确保该函数多次调用,只打开一次设备。
if(!lock) 
{
lock = 1; //snd_pcm_close()内会清零该lock,以便下次再打开设备

ret= snd_pcm_open(&handle, "default",    \
SND_PCM_STREAM_PLAYBACK, 0);
if(ret<0)
{
printf("open PCM device failed\n");
}
}
snd_pcm_hw_params_alloca(&params); //分配params结构体

ret= snd_pcm_hw_params_any(handle, params);//初始化params
if(ret<0)
{
printf("snd_pcm_hw_params_any err\n");
}
ret= snd_pcm_hw_params_set_access(handle, params, \
SND_PCM_ACCESS_RW_INTERLEAVED); //初始化访问权限
if(ret<0)
{
printf("sed_pcm_hw_set_access err\n");
}
//采样位数
switch(bit/8)
{
case 1:snd_pcm_hw_params_set_format(handle, params,\
SND_PCM_FORMAT_U8);
break ;
case 2:snd_pcm_hw_params_set_format(handle, params,\
SND_PCM_FORMAT_S16_LE);
break ;
case 3:snd_pcm_hw_params_set_format(handle, params,\
SND_PCM_FORMAT_S24_LE);
break ;
default:
printf("default \n");
break;
}
ret= snd_pcm_hw_params_set_channels(handle, params,    \
channels); //设置声道,1表示单声>道,2表示立体声
if(ret<0)
{
printf("snd_pcm_hw_params_set_channels err\n");
}
val = frequency;
ret= snd_pcm_hw_params_set_rate_near(handle, params,   \
&val, &dir); //设置>频率
if(ret<0)
{
printf("snd_pcm_hw_params_set_rate_near err\n");
}
ret = snd_pcm_hw_params(handle, params);
if(ret<0)
{
printf("snd_pcm_hw_params err \n");
}
ret=snd_pcm_hw_params_get_period_size(params, pframes, \
&dir); /*获取周期长度*/
if(ret<0)
{
printf("snd_pcm_hw_params_get_period_size err\n");
}
// 一个数据块,一个数据块,依次读取。
size = (*pframes) * datablock; /*代表数据块长度*/
printf("--malloc(size), size = %d \n",size);
return size;
}
#define max_num  5
struct wav_file_info {
FILE* fp;
int size;
snd_pcm_uframes_t frames;
short channels;
int frequency;
short bit;
short datablock; 
}wavinfo[max_num];
/*
path1 = malloc(50);
path2 = malloc(50);
sprintf(path1,"/TG/sound/%d.wav", 1);
sprintf(path2,"/TG/sound/%d.wav", 2);
*/
//void Get_fp_and_wavheader(const char* path, FILE **pfp, struct wav_header* phead_info)
FILE * Get_fp_and_wavheader(const char* path, struct wav_header* phead_info)
{
if(NULL != path) {
printf("path = %s \n", path);
FILE *fp=fopen(path,"rb");
if(NULL==fp)
{
printf("open wav failed:\n");
return NULL;
}
printf("fp = %p \n", fp);
fread(phead_info, 1, sizeof(struct wav_header),fp);
return fp;
/*  
printf("文件大小rLen:   %d\n", phead_info->rLen);
printf("声道数:        %d\n", phead_info->wChannels);
printf("采样频率:      %d\n", phead_info->nSamplesPersec);
printf("采样的位数:     %d\n", phead_info->wBitsPerSample);
printf("wSampleLength=%d\n", phead_info->wSampleLength);
*/
}
}
// 对fopen的理解:
// 即使3次fopen同一个文件,也不要紧,会返回3个不同的fp,但是指向同一个文件.
int set_pcm_play(const char* path1, const char* path2, const char* path3)
{
int ret;
unsigned int size = 0;
unsigned int size1 = 0, size2 = 0, size3 = 0;
int num=0;
int dir=0;
snd_pcm_uframes_t frames, frames1, frames2, frames3;
char *buffer;
int channels;
int frequency;
int bit;
int datablock;
FILE *fp1 = NULL, *fp2 = NULL, *fp3 = NULL;  
FILE* fpCur[max_num] = {0};
const char* file_paths[3] = {0};
file_paths[0] = path1;
file_paths[1] = path2;
file_paths[2] = path3;            
if(NULL != path3) {
fp3 = Get_fp_and_wavheader(path3, &wav_header3);
if(fp3 != NULL) {
channels = wav_header3.wChannels;
frequency= wav_header3.nSamplesPersec;
bit      = wav_header3.wBitsPerSample;
datablock= wav_header3.wBlockAlign; 
#if 0 
printf("fp3 datablock:   %d\n",   datablock);
printf("声道数:        %d\n", channels);
printf("采样频率:      %d\n", frequency);
printf("采样的位数:     %d\n", bit);
printf("wSampleLength=%d\n\n\n", wav_header3.wSampleLength);
#endif
wavinfo[2].channels = channels;
wavinfo[2].frequency = frequency;
wavinfo[2].bit = bit;
wavinfo[2].datablock = datablock;
size3 = para_common_set(channels, frequency, bit, datablock, &frames3);
//获取各自的rames。
wavinfo[2].size = size3; 
wavinfo[2].frames = frames3;
}
}
if(NULL != path2) {
fp2 = Get_fp_and_wavheader(path2, &wav_header2);
if(fp2 != NULL) {
channels = wav_header2.wChannels;
frequency= wav_header2.nSamplesPersec;
bit      = wav_header2.wBitsPerSample;
datablock= wav_header2.wBlockAlign; 
#if 0 
printf("fp2 datablock:   %d\n",   datablock);
printf("声道数:        %d\n", channels);
printf("采样频率:      %d\n", frequency);
printf("采样的位数:     %d\n", bit);
printf("wSampleLength=%d\n\n\n", wav_header2.wSampleLength);
#endif
wavinfo[1].channels = channels;
wavinfo[1].frequency = frequency;
wavinfo[1].bit = bit;
wavinfo[1].datablock = datablock;
size2 = para_common_set(channels, frequency, bit, datablock, &frames2);
//获取各自的rames。
wavinfo[1].size = size2; 
wavinfo[1].frames = frames2;
}
}
if(NULL != path1) {
#if 1
// 对fopen的理解:
// 即使3次fopen同一个文件,也不要紧,会返回3个不同的fp,但是指向同一个文件.
fp1 = Get_fp_and_wavheader(path1, &wav_header1);
#else
char *path111 = malloc(50);
sprintf(path111,"/TG/sound/%d.wav", 1);
fp1=fopen(path111,"rb");
if(fp1==NULL)
{
printf("open wav1 failed:\n");
return -1;
}
fread(&wav_header1,1,sizeof(wav_header1),fp1);
#endif
// 实际上给入的每个音频文件的采样率啥的都是一样的,但是每个音频文件的大小可能不一样,
// 所以需要单独针对每个音频文件设置这里,获取各自的frames。
if(fp1 != NULL) {
printf("fp1 = %p \n", fp1);
channels = wav_header1.wChannels;
frequency= wav_header1.nSamplesPersec;
bit      = wav_header1.wBitsPerSample;
datablock= wav_header1.wBlockAlign; 
#if 0 
printf("fp1 datablock:   %d\n",   datablock);
printf("声道数:        %d\n", channels);
printf("采样频率:      %d\n", frequency);
printf("采样的位数:     %d\n", bit);
printf("wSampleLength=%d\n\n\n", wav_header1.wSampleLength);
#endif
wavinfo[0].channels = channels;
wavinfo[0].frequency = frequency;
wavinfo[0].bit = bit;
wavinfo[0].datablock = datablock;
size1 = para_common_set(channels, frequency, bit, datablock, &frames1);
//获取各自的rames。
wavinfo[0].size = size1; 
wavinfo[0].frames = frames1;
//    printf("size1 = %d \n",size1);
//    printf("wavinfo[0].size = %d \n", wavinfo[0].size);

}
}
wavinfo[0].fp = fp1;
wavinfo[1].fp = fp2;
wavinfo[2].fp = fp3;
#if 0    
printf("wavinfo[0].fp = %d \n", wavinfo[0].fp);
printf("fp1 = %d \n", fp1);                
#endif
if(size1 > size2) {
size = size1;
}
else {
size = size2;
}
if(size > size3) {
}
else {
size = size3;
}
printf("size = %d \n", size);
buffer = (char*)malloc(size);
#if 1
// fseek(fp1, 58, SEEK_SET);
//printf("wavinfo[0].fp = %d \n", wavinfo[0].fp);
//printf("fp1 = %d \n", fp1);    
if(wavinfo[0].fp) {                
fseek(wavinfo[0].fp, 44, SEEK_SET); //定位歌曲到数据区
                }
if(wavinfo[1].fp) {               
printf("--2 \n");
fseek(wavinfo[1].fp, 44, SEEK_SET); //定位歌曲到数据区
                }
if(wavinfo[2].fp) {                
printf("--3 \n");
fseek(wavinfo[2].fp, 44, SEEK_SET); //定位歌曲到数据区
                }
#endif
int index = 0;
//    printf("-wavinfo[0].fp = %d \n", wavinfo[0].fp);
//    printf("-wavinfo[1].fp = %d \n", wavinfo[1].fp);
//    printf("-wavinfo[2].fp = %d \n", wavinfo[2].fp);
while ((g_stop == 0) && (wavinfo[index].fp))
{
num++;
memset(buffer, 0x00, size);
if(wavinfo[index].fp) {
// 一个数据块,一个数据块,依次读取。
ret = fread(buffer, 1, wavinfo[index].size, wavinfo[index].fp);
if(ret == 0) {
printf("曲目读取 end\n");
fclose(wavinfo[index].fp);
wavinfo[index].fp = NULL;
index++;
continue;  
//printf("--not reached here \n");
                                            
}
else if (ret != size) {
printf("left: read %d bytes\n", ret);
}
//printf("-play %d\n", ret);
// 写音频数据到PCM设备 
//struct timeval time1,time2;
//gettimeofday(&time1,NULL); 

ret = snd_pcm_writei(handle, buffer, wavinfo[index].frames);
//snd_pcm_prepare(handle);
//gettimeofday(&time2,NULL);
//printf("time=%d\n",            \
(time2.tv_sec-time1.tv_sec)*1000000+time2.tv_usec-time1.tv_usec);
if (ret == -EPIPE)
{
printf("underrun occurred\n");
//完成硬件参数设置,使设备准备好 
snd_pcm_prepare(handle); // 继续
                                    }
else if (ret < 0)
{
printf("error from writei: %s\n",snd_strerror(ret));
}
else if (ret != (int)wavinfo[index].frames) 
{
printf("short write, write %d frames\n", ret);
}
}
}
snd_pcm_drain(handle); // 清空pcm内部音频数据流缓存
snd_pcm_drop(handle);  // 暂停
int i=0;
for(i=0; i<max_num; i++)
{
if(wavinfo[i].fp)
fclose(wavinfo[i].fp);
}
lock = 0;
snd_pcm_close(handle);
free(buffer);
handle = NULL;
g_stop=0;
return 0;
}

makefile:

.PHONY : rebuild clean
CC:= mips-linux-gnu-gcc
TARGET:= alsa_test.out
OBJS:= alsa_test.o 
# 老旧知识点: -I -L -l 详解  
#-I /home/hello/include   表示将/home/hello/include目录作为第一个寻找头文件的目录
#-L /home/hello/lib   表示将/home/hello/lib目录作为第一个寻找库文件的目录
#-lworld      表示在上面的lib的路径中寻找libworld.so动态库文件(如果gcc编译选项中加入了“-static”表示寻找libworld.a静态库文件)
INCLUDE += -I /usr/local/open_lib/include
LIBS += -lpthread -L/usr/local/open_lib/lib -lasound
$(TARGET) :$(OBJS)
$(CC) $(LIBS) $^ -o [email protected] 
$(OBJS):%.o:%.c
$(CC) $(INCLUDE) -c $^ -o [email protected]
echo $(OBJS)
clean:
$(RM) $(OBJS)
$(RM) $(TARGET)
@echo "clean"
rebuild : clean $(TARGET)
@echo "rebuild"

本例子在项目中,功能使用良好。

 

 

 

 

 

 

 

 

 

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