场景：【硬触发】环境触发频率快时，相机内缓存图片（默认节点数量为1）有可能被不停刷新，导致无法及时捕捉到每次触发响应的图片。
方案：SDK中可以设置相机内部缓冲节点数量和取图策略。
nRet = MV_CC_SetImageNodeNum(handle, nImageNodeNum);
handle（相机句柄）
nImageNodeNum：节点数量（初始化为1）
MV_GrabStrategy_OneByOne
从旧到新一帧一帧的获取图像（默认为该策略）
MV_GrabStrategy_LatestImagesOnly
获取列表中最新的一帧图像（同时清除列表中的其余图像）
MV_GrabStrategy_LatestImages
获取列表中最新的图像，个数由OutputQueueSize决定，范围为1-ImageNodeNum，设置成1等同于LatestImagesOnly,设置成ImageNodeNum等同于OneByOne
MV_GrabStrategy_UpcomingImage
等待下一帧图像
示例：
#include <stdio.h>
#include <Windows.h>
#include <process.h>
#include <conio.h>
#include "MvCameraControl.h"
// Wait for key press
void WaitForKeyPress(void)
{
while(!_kbhit())
{
Sleep(10);
}
_getch();
}
bool PrintDeviceInfo(MV_CC_DEVICE_INFO* pstMVDevInfo)
{
if (NULL == pstMVDevInfo)
{
printf("The Pointer of pstMVDevInfo is NULL!\n");
return false;
}
if (pstMVDevInfo->nTLayerType == MV_GIGE_DEVICE)
{
int nIp1 = ((pstMVDevInfo->SpecialInfo.stGigEInfo.nCurrentIp & 0xff000000) >> 24);
int nIp2 = ((pstMVDevInfo->SpecialInfo.stGigEInfo.nCurrentIp & 0x00ff0000) >> 16);
int nIp3 = ((pstMVDevInfo->SpecialInfo.stGigEInfo.nCurrentIp & 0x0000ff00) >> 8);
int nIp4 = (pstMVDevInfo->SpecialInfo.stGigEInfo.nCurrentIp & 0x000000ff);
printf("CurrentIp: %d.%d.%d.%d\n" , nIp1, nIp2, nIp3, nIp4);
printf("UserDefinedName: %s\n\n" , pstMVDevInfo->SpecialInfo.stGigEInfo.chUserDefinedName);
}
else if (pstMVDevInfo->nTLayerType == MV_USB_DEVICE)
{
printf("UserDefinedName: %s\n", pstMVDevInfo->SpecialInfo.stUsb3VInfo.chUserDefinedName);
printf("Serial Number: %s\n", pstMVDevInfo->SpecialInfo.stUsb3VInfo.chSerialNumber);
printf("Device Number: %d\n\n", pstMVDevInfo->SpecialInfo.stUsb3VInfo.nDeviceNumber);
}
else
{
printf("Not support.\n");
}
return true;
}
static unsigned int __stdcall UpcomingThread(void* pUser)
{
Sleep(3000);
printf("Trigger Software Once for MV_GrabStrategy_UpcomingImage\n");
MV_CC_SetCommandValue(pUser, "TriggerSoftware");
return 0;
}
int main()
{
int nRet = MV_OK;
void* handle = NULL;
unsigned char * pData = NULL;
do
{
// Enum device
MV_CC_DEVICE_INFO_LIST stDeviceList = {0};
nRet = MV_CC_EnumDevices(MV_GIGE_DEVICE | MV_USB_DEVICE, &stDeviceList);
if (MV_OK != nRet)
{
printf("Enum Devices fail! nRet [0x%x]\n", nRet);
break;
}
if (stDeviceList.nDeviceNum > 0)
{
for (unsigned int i = 0; i < stDeviceList.nDeviceNum; i++)
{
printf("[device %d]:\n", i);
MV_CC_DEVICE_INFO* pDeviceInfo = stDeviceList.pDeviceInfo[i];
if (NULL == pDeviceInfo)
{
break;
}
PrintDeviceInfo(pDeviceInfo);
}
}
else
{
printf("Find No Devices!\n");
break;
}
printf("Please Input camera index:");
unsigned int nIndex = 0;
scanf_s("%d", &nIndex);
if (nIndex >= stDeviceList.nDeviceNum)
{
printf("Input error!\n");
break;
}
// Select device and create handle
nRet = MV_CC_CreateHandle(&handle, stDeviceList.pDeviceInfo[nIndex]);
if (MV_OK != nRet)
{
printf("Create Handle fail! nRet [0x%x]\n", nRet);
break;
}
// Open device
nRet = MV_CC_OpenDevice(handle);
if (MV_OK != nRet)
{
printf("Open Device fail! nRet [0x%x]\n", nRet);
break;
}
// Detection network optimal package size(It only works for the GigE camera)
if (stDeviceList.pDeviceInfo[nIndex]->nTLayerType == MV_GIGE_DEVICE)
{
int nPacketSize = MV_CC_GetOptimalPacketSize(handle);
if (nPacketSize > 0)
{
if(MV_CC_SetIntValue(handle,"GevSCPSPacketSize",nPacketSize) != MV_OK)
{
printf("Warning: Set Packet Size fail nRet [0x%x]!", nRet);
}
}
else
{
printf("Warning: Get Packet Size fail nRet [0x%x]!", nPacketSize);
}
}
// Set Trigger Mode and Set Trigger Source
nRet = MV_CC_SetEnumValueByString(handle, "TriggerMode", "On");
if (MV_OK != nRet)
{
printf("Set Trigger Mode fail! nRet [0x%x]\n", nRet);
break;
}
nRet = MV_CC_SetEnumValueByString(handle, "TriggerSource", "Software");
if (MV_OK != nRet)
{
printf("Set Trigger Source fail! nRet [0x%x]\n", nRet);
break;
}
unsigned int nImageNodeNum = 5;
// Set number of image node
nRet = MV_CC_SetImageNodeNum(handle, nImageNodeNum);
if (MV_OK != nRet)
{
printf("Set number of image node fail! nRet [0x%x]\n", nRet);
break;
}
printf("\n**************************************************************************\n");
printf("* 0.MV_GrabStrategy_OneByOne; 1.MV_GrabStrategy_LatestImagesOnly; *\n");
printf("* 2.MV_GrabStrategy_LatestImages; 3.MV_GrabStrategy_UpcomingImage; *\n");
printf("**************************************************************************\n");
printf("Please Input Grab Strategy:");
unsigned int nGrabStrategy = 0;
scanf_s("%d", &nGrabStrategy);
// U3V device not support UpcomingImage
if (nGrabStrategy == MV_GrabStrategy_UpcomingImage && MV_USB_DEVICE == stDeviceList.pDeviceInfo[nIndex]->nTLayerType)
{
printf("U3V device not support UpcomingImage\n");
break;
}
switch(nGrabStrategy)
{
case MV_GrabStrategy_OneByOne:
{
printf("Grab using the MV_GrabStrategy_OneByOne default strategy\n");
nRet = MV_CC_SetGrabStrategy(handle, MV_GrabStrategy_OneByOne);
if (MV_OK != nRet)
{
printf("Set Grab Strategy fail! nRet [0x%x]\n", nRet);
break;
}
}
break;
case MV_GrabStrategy_LatestImagesOnly:
{
printf("Grab using strategy MV_GrabStrategy_LatestImagesOnly\n");
nRet = MV_CC_SetGrabStrategy(handle, MV_GrabStrategy_LatestImagesOnly);
if (MV_OK != nRet)
{
printf("Set Grab Strategy fail! nRet [0x%x]\n", nRet);
break;
}
}
break;
case MV_GrabStrategy_LatestImages:
{
printf("Grab using strategy MV_GrabStrategy_LatestImages\n");
nRet = MV_CC_SetGrabStrategy(handle, MV_GrabStrategy_LatestImages);
if (MV_OK != nRet)
{
printf("Set Grab Strategy fail! nRet [0x%x]\n", nRet);
break;
}
// Set Output Queue Size
nRet = MV_CC_SetOutputQueueSize(handle, 2);
if (MV_OK != nRet)
{
printf("Set Output Queue Size fail! nRet [0x%x]\n", nRet);
break;
}
}
break;
case MV_GrabStrategy_UpcomingImage:
{
printf("Grab using strategy MV_GrabStrategy_UpcomingImage\n");
nRet = MV_CC_SetGrabStrategy(handle, MV_GrabStrategy_UpcomingImage);
if (MV_OK != nRet)
{
printf("Set Grab Strategy fail! nRet [0x%x]\n", nRet);
break;
}
unsigned int nThreadID = 0;
void* hThreadHandle = (void*) _beginthreadex( NULL , 0 , UpcomingThread , handle, 0 , &nThreadID );
if (NULL == hThreadHandle)
{
break;
}
}
break;
default:
printf("Input error!Use default strategy:MV_GrabStrategy_OneByOne\n");
break;
}
// Start grab image
nRet = MV_CC_StartGrabbing(handle);
if (MV_OK != nRet)
{
printf("Start Grabbing fail! nRet [0x%x]\n", nRet);
break;
}
// Send Trigger Software command
for (unsigned int i = 0;i < nImageNodeNum;i++)
{
nRet = MV_CC_SetCommandValue(handle, "TriggerSoftware");
if (MV_OK != nRet)
{
printf("Send Trigger Software command fail! nRet [0x%x]\n", nRet);
break;
}
Sleep(500);
}
MV_FRAME_OUT stOutFrame = {0};
if (nGrabStrategy != MV_GrabStrategy_UpcomingImage)
{
while(true)
{
nRet = MV_CC_GetImageBuffer(handle, &stOutFrame, 0);
if (nRet == MV_OK)
{
printf("Get One Frame: Width[%d], Height[%d], FrameNum[%d]\n",
stOutFrame.stFrameInfo.nWidth, stOutFrame.stFrameInfo.nHeight, stOutFrame.stFrameInfo.nFrameNum);
}
else
{
printf("No data[0x%x]\n", nRet);
break;
}
nRet = MV_CC_FreeImageBuffer(handle, &stOutFrame);
if(nRet != MV_OK)
{
printf("Free Image Buffer fail! nRet [0x%x]\n", nRet);
}
}
}
else//Only for upcoming
{
nRet = MV_CC_GetImageBuffer(handle, &stOutFrame, 5000);
if (nRet == MV_OK)
{
printf("Get One Frame: Width[%d], Height[%d], FrameNum[%d]\n",
stOutFrame.stFrameInfo.nWidth, stOutFrame.stFrameInfo.nHeight, stOutFrame.stFrameInfo.nFrameNum);
nRet = MV_CC_FreeImageBuffer(handle, &stOutFrame);
if(nRet != MV_OK)
{
printf("Free Image Buffer fail! nRet [0x%x]\n", nRet);
}
}
else
{
printf("No data[0x%x]\n", nRet);
}
}
// Stop grab image
nRet = MV_CC_StopGrabbing(handle);
if (MV_OK != nRet)
{
printf("Stop Grabbing fail! nRet [0x%x]\n", nRet);
break;
}
// Close device
nRet = MV_CC_CloseDevice(handle);
if (MV_OK != nRet)
{
printf("Close Device fail! nRet [0x%x]\n", nRet);
break;
}
// Destroy handle
nRet = MV_CC_DestroyHandle(handle);
if (MV_OK != nRet)
{
printf("Destroy Handle fail! nRet [0x%x]\n", nRet);
break;
}
} while (0);
if (nRet != MV_OK)
{
if (handle != NULL)
{
MV_CC_DestroyHandle(handle);
handle = NULL;
}
}
printf("Press a key to exit.\n");
WaitForKeyPress();
return 0;