本文共 9848 字，大约阅读时间需要 32 分钟。

本需求系列文章:

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本文接着《》

二、共享内存接收端代码实现

1. 头文件 H264_Reverse.h

# nativecamerasdk/video/H264_Reverse.h#ifndef __H264_REVERSE_H__  #define __H264_REVERSE_H__#define DLS_CAMERA_PREVIEW_WIDTH 	720  	//raw camera output#define DLS_CAMERA_PREVIEW_HEIGHT	480 	//raw camera output//YUV420-N21      YYYYYYYY UVUV#define MAX_BUF_SIZE 	DLS_CAMERA_PREVIEW_WIDTH * DLS_CAMERA_PREVIEW_HEIGHT * 3/2 + 200#define  REVERSE_CAMERA_DUMP_LOCATION  "/sdcard/reverse/"// 进程锁结构体typedef struct MUTEX_SHAREDLOCK {
       pthread_mutex_t lock;    pthread_mutexattr_t lock_attr;} mutex_sharedLock_t;class Camera_Shared_Memory_R{
   public:	static Camera_Shared_Memory_R* get_Read_Shared_Memory();	int attach_Read_Shared_Memory();	int open_Read_Shared_Memory(unsigned char *buffer);	int close_Read_Shared_Memory();	int shm_chn_attach();				unsigned char * shm_addr_buff;		// dump data	void Camera_Shared_Memory_Dump(unsigned char * buf, int size);private:	//method declare  		Camera_Shared_Memory_R();	~Camera_Shared_Memory_R();	static Camera_Shared_Memory_R* sInstance;		void* shm_addr;		int shm_id;	};#endif   // END __H264_REVERSE_H__

2. 源文件 H264_Reverse.cpp

# nativecamerasdk/video/H264_Reverse.cpp#include 
   
    #include 
    
     #include 
     
      #include 
      
       #include 
       
        #include 
        
         #include 
         
          #include 
          
           #include 
           
            #include "H264_Reverse.h"static mutex_sharedLock_t *sharedLock_r;Camera_Shared_Memory_R* Camera_Shared_Memory_R::sInstance = 0;Camera_Shared_Memory_R::Camera_Shared_Memory_R():shm_addr(NULL),shm_id(0){ attach_Read_Shared_Memory(); // alloc buffer shm_addr_buff = (unsigned char *)malloc(MAX_BUF_SIZE);}Camera_Shared_Memory_R::~Camera_Shared_Memory_R(){ // release addr close_Read_Shared_Memory(); // who create who destroy, so don't delete IPC memory here //if(shmctl(shm_id, IPC_RMID, NULL) !=0 ) // ALOGI("[%s][%d] shmctl error!,shm_id=%d \n", __func__,__LINE__, shm_id); // free buffer free(shm_addr_buff); shm_id = -1;}Camera_Shared_Memory_R* Camera_Shared_Memory_R::get_Read_Shared_Memory(){ if(!Camera_Shared_Memory_R::sInstance) { Camera_Shared_Memory_R::sInstance = new Camera_Shared_Memory_R; } return Camera_Shared_Memory_R::sInstance;}int Camera_Shared_Memory_R::attach_Read_Shared_Memory(){ return Camera_Shared_Memory_R::shm_chn_attach();}int Camera_Shared_Memory_R::shm_chn_attach(){ shm_id = shmget((key_t)1225, 0, 0); if(-1== shm_id) { ALOGI("[reverse_exe][%s][%d] share memory get error!\n",__func__, __LINE__); goto err; } shm_addr= shmat(shm_id, 0, 0); if((void *)-1== shm_addr) { ALOGI("[reverse_exe][%s][%d] share memory attach address error\n",__func__, __LINE__); goto err; } sharedLock_r = (mutex_sharedLock_t *)shm_addr; return 0;err: return -1;}int Camera_Shared_Memory_R::open_Read_Shared_Memory(unsigned char *buffer){ //pthread_mutex_lock( &(sharedLock_r->lock) ); if (0 == pthread_mutex_trylock( &(sharedLock_r->lock))) { memcpy(buffer, ((pthread_mutex_t *)shm_addr)+1, MAX_BUF_SIZE); ALOGI("[reverse_exe][%s][%d] buffer -- %x-%x-%x-%x - %x-%x-%x-%x - %x-%x-%x-%x",__func__,__LINE__, buffer[0],buffer[1],buffer[2],buffer[3],buffer[4],buffer[5],buffer[6], buffer[7],buffer[8],buffer[9],buffer[10],buffer[11]); pthread_mutex_unlock( &(sharedLock_r->lock) ); }else{ ALOGI("[reverse_exe][%s][%d] lock is busy \n", __func__,__LINE__); return -1; } return 0;}int Camera_Shared_Memory_R::close_Read_Shared_Memory(){ ALOGI("[%s][%d] shm_id=%d, shm_addr=%p \n", __func__,__LINE__, shm_id, shm_addr); // release shm_addr if ((shm_addr != NULL) && shmdt(shm_addr) == -1) { ALOGI("[%s][%d] shmdt error!,shm_addr=%p \n", __func__,__LINE__, shm_addr); return -1; } return 0;}//// save yuv file in /sdcard/reverse/Rear-Camera-720x480-0.yuvstatic int index = 0;void Camera_Shared_Memory_R::Camera_Shared_Memory_Dump(unsigned char * buf, int size){ char filename_buf[128]; if(index >= 200){ ALOGI("[reverse_exe][%s][%d] index=%d ,too big \n",__func__, __LINE__, index); return; } if(access(REVERSE_CAMERA_DUMP_LOCATION,F_OK) != 0){ printf("create new path!\n"); mkdir(REVERSE_CAMERA_DUMP_LOCATION, S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH); } snprintf(filename_buf, sizeof(filename_buf), "%sRear-Camera-720x480-%d.yuv", REVERSE_CAMERA_DUMP_LOCATION, index); ALOGI("[reverse_exe][%s][%d] filename_buf=%s \n",__func__, __LINE__, filename_buf); int file_fd = open(filename_buf, O_RDWR | O_CREAT, 0777); ssize_t written_len = 0; if (file_fd >= 0){ fchmod(file_fd, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH); write(file_fd, buf, MAX_BUF_SIZE); close(file_fd); index ++; }else{ ALOGE("%s: fail t open file for image dumping", __func__); }}
           
          
         
        
       
      
     
    
   

3. 测试Daemon代码 H264_Reverse.cpp

# nativecamerasdk/native_camera_impl.cpp//ciellee +++#include "video/H264_Reverse.h"      DMSDPSendBackDataCB reverse_sendbackFrameFunc = nullptr;static int reverse_capturing = 0;// 注册Camera 数据回调函数int32_t CameraRegisterSendDataCallback(const char* id, uint32_t idLen, const DMSDPSendBackDataCB cb){
       /* regist callback senddata */    ALOGI("CameraRegisterSendDataCallback");    // ciellee +++    if( strcmp(id, "5") == 0 ) {
   			// id = 5, reverse_camera        reverse_sendbackFrameFunc = cb;    }    return DMSDP_NO_ERROR;}// 数据采集线程void * cap_reverse (void *arg){
   	ALOGI("[reverse_exe][%s][%d] Enter ... \n",__func__, __LINE__);    // 1. init    Camera_Shared_Memory_R * Camera_Shared_Memory_r = Camera_Shared_Memory_R::get_Read_Shared_Memory();    	while(reverse_capturing)	{
           memset(Camera_Shared_Memory_r->shm_addr_buff, 0, MAX_BUF_SIZE);        // 2. read shm data        Camera_Shared_Memory_r->open_Read_Shared_Memory(Camera_Shared_Memory_r->shm_addr_buff);        // 3. daemon ,save data with yuv file        Camera_Shared_Memory_r->Camera_Shared_Memory_Dump(Camera_Shared_Memory_r->shm_addr_buff , MAX_BUF_SIZE);        // here call callback send buff        //sendbackFrameFunc( id_s , sizeof(id_s), Camera_Shared_Memory_r->shm_addr_buff, MAX_BUF_SIZE, (int32_t)DMSDPCameraDataType::H264);                usleep(30000);  //sleep 30ms	}	pthread_exit(NULL);}// 打开摄像头，开始启动数据采集线程int32_t OpenCamera(const DMSDPCameraParam* param) {
       if (param == nullptr) {
           ALOGE("%s: open camera param is null", __FUNCTION__);        return DMSDP_ERR_INVALID_PARAMETER;    }    ALOGI("[reverse_exe][%s][%d] id=%s \n",__func__, __LINE__, param->id);    if( strcmp(param->id, "5") == 0 )		// id = 5, reverse_camera    {
   	    	// init share memory         Camera_Shared_Memory_R * Camera_Shared_Memory_r = Camera_Shared_Memory_R::get_Read_Shared_Memory();        reverse_capturing = 1;        // start pthread        pthread_t pthreadReverse;        if (pthread_create(&pthreadReverse, nullptr, cap_reverse, nullptr))            ALOGI("%s: Create cap_reverse error!", __FUNCTION__);        if (pthreadReverse != 0)        {
               pthread_detach(pthreadReverse);            ALOGI("%s: capture h264 preview exit", __FUNCTION__);        }    }    ALOGI("%s: open camera success", __FUNCTION__);    return DMSDP_NO_ERROR;}// 关闭数据采集int32_t CloseCamera(const char* id, uint32_t idLen){
       if( strcmp(id, "5") == 0 ){
           reverse_capturing = 0;    }    return DMSDP_NO_ERROR;}// Daemon 主函数，后续，该部分调用由华为来实现int main(void){
       char id_test[] = "5";    const char *id_pt = id_test;    DMSDPCameraParam param_test;    param_test.id = id_pt;        // 1. register  callback     // CameraRegisterSendDataCallback    // 2. open camera get data    OpenCamera(&param_test);        while(1){
           sleep(10);    }    return 0;}

三、Daemon 实测

1. 发送端log 输出

通过 PCAN ，往车机发送倒车命令后，进入倒车模式，开启倒车摄像头，

ciellee@sh:~/tamp$ adb logcat -b all | grep Shared_Memory05-29 10:50:45.740   798   930 I         : [create_Shared_Memory][46] shm_id : 005-29 10:50:45.741   798   930 I         : [create_Shared_Memory][67] add shm_id=0, shm_addr=0xb2887000

2. 接收端log 输出

执行可执行程序： msm8937_32go:/ # libdmsdpcamerahandler_exe

05-29 10:51:12.932  7616  7616 I CamSDK_3rdCamera: [reverse_exe][OpenCamera][569] id=5 05-29 10:51:12.939  7616  7618 I CamSDK_3rdCamera: [reverse_exe][cap_reverse][543] Enter ... 05-29 10:51:12.957  7616  7618 I : [reverse_exe][open_Read_Shared_Memory][84] buffer -- d2-d2-d2-d2 - d2-d2-d2-d2 - d2-d2-d2-d205-29 10:51:12.967  7616  7618 I : [reverse_exe][Camera_Shared_Memory_Dump][132] filename_buf=/sdcard/reverse/Rear-Camera-720x480-0.yuv  05-29 10:51:13.004  7616  7618 I : [reverse_exe][open_Read_Shared_Memory][84] buffer -- d2-d2-d2-d2 - d2-d2-d2-d2 - d2-d2-d2-d205-29 10:51:13.004  7616  7618 I : [reverse_exe][Camera_Shared_Memory_Dump][132] filename_buf=/sdcard/reverse/Rear-Camera-720x480-1.yuv  05-29 10:51:13.041  7616  7618 I : [reverse_exe][open_Read_Shared_Memory][84] buffer -- d2-d2-d2-d2 - d2-d2-d2-d2 - d2-d2-d2-d205-29 10:51:13.041  7616  7618 I : [reverse_exe][Camera_Shared_Memory_Dump][132] filename_buf=/sdcard/reverse/Rear-Camera-720x480-2.yuv  05-29 10:51:13.083  7616  7618 I : [reverse_exe][open_Read_Shared_Memory][84] buffer -- d2-d2-d2-d2 - d2-d2-d2-d2 - d2-d2-d2-d2

3. 导出YUV 图片

ciellee@sh:~/tamp$ adb pull /sdcard/reverse/ .pull: building file list...pull: /sdcard/reverse/Rear-Camera-720x480-47.yuv -> ./Rear-Camera-720x480-47.yuvpull: /sdcard/reverse/Rear-Camera-720x480-46.yuv -> ./Rear-Camera-720x480-46.yuvpull: /sdcard/reverse/Rear-Camera-720x480-45.yuv -> ./Rear-Camera-720x480-45.yuvpull: /sdcard/reverse/Rear-Camera-720x480-44.yuv -> ./Rear-Camera-720x480-44.yuvpull: /sdcard/reverse/Rear-Camera-720x480-43.yuv -> ./Rear-Camera-720x480-43.yuvpull: /sdcard/reverse/Rear-Camera-720x480-42.yuv -> ./Rear-Camera-720x480-42.yuv

查看图片：

如下是获取的 pattern 图：

四、下一步工作

现在共享内存 Deamon 写好了，已经发邮件请华为安排一位研发和我对接联调。

1. 和 xxx 工程师联调 xxx 倒车影像功能
2. 使用C++ ADIL 来代替 共享内存 ，实现进程间大数据传输

参考：《》

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