双camera同时打开

原文链接：http://blog.csdn.net/a87636764/article/details/54645350

平台：android5.1  场景：双屏异显设备需求在两个屏上同时打开两个摄像头，确认可行性。  时间：2016.9.28

双camera示例代码：

this.mSurfaceHolder = this.sfv1.getHolder(); this.mSurfaceHolder.addCallback(new SurfaceHolder.Callback() { @Override public void surfaceDestroyed(SurfaceHolder arg0) { // TODO Auto-generated method stub } @Override public void surfaceCreated(SurfaceHolder arg0) { // TODO Auto-generated method stub Camera mcamera = Camera.open(0); mcamera.setDisplayOrientation(90); try { mcamera.setPreviewDisplay(mSurfaceHolder); mcamera.startPreview(); return; } catch (IOException localIOException) { localIOException.printStackTrace(); } } @Override public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) { // TODO Auto-generated method stub } }); this.mSurfaceHolder.setType(3); this.mSurfaceHolder1 = this.sfv2.getHolder(); this.mSurfaceHolder1.addCallback(new SurfaceHolder.Callback() { @Override public void surfaceDestroyed(SurfaceHolder arg0) { // TODO Auto-generated method stub } @Override public void surfaceCreated(SurfaceHolder arg0) { // TODO Auto-generated method stub Camera mcamera = Camera.open(1); mcamera.setDisplayOrientation(90); try { mcamera.setPreviewDisplay(mSurfaceHolder1); mcamera.startPreview(); return; } catch (IOException localIOException) { localIOException.printStackTrace(); } } @Override public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) { // TODO Auto-generated method stub } }); this.mSurfaceHolder1.setType(3); 1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859 1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859

双Camera同时工作需要硬件设计支持：两路ISP，以及MCLK，I2C是否共用等。

当硬件支持后，如果软件没有支持，则基本上会在Camera.open(1)报错，从此处开始给出调用链：

Camera.java::open() native_setup() 12 12 android_hardware_Camera.cpp::android_hardware_Camera_native_setup() //Camera::connect() 1 1 CameraBase.cpp::connect() //(cs.get()->*fnConnectService)(cl, cameraId, clientPackageName, clientUid,/*out*/ c->mCamera)，此处fnConnectService为connect，即CameraService的connect函数。 1 1 CameraService.cpp::connect() //CameraService::onFirstRef()通过hw_get_module(CAMERA_HARDWARE_MODULE_ID, (const hw_module_t **)&mModule)的调用，将module获取。而后在connect()中通过CAMERA_DEVICE_API_VERSION_来创建对应的clinet，KK版本使用的1_0版本，即CameraClient对象。 12 12 connectFinishUnsafe() //此函数调用client->initialize(mModule)。CameraClient::initialize()，建立CameraHardwareInterface对象，并调用其initialize()，继而 module->methods->open()，获取到hw_device_t对象。 12 12

以上对open()调用，已经切入到HAL中。双camera同时工作的判断基本都放在此open()中：  Intel 4.4平台示例：

static int ATOM_OpenCameraHardware(const hw_module_t* module, const char* name, hw_device_t** device) { ... if ((!PlatformData::supportDualVideo() && atom_instances == 1) || atom_instances > MAX_HAL_INSTANCES-1) { LOGE("error:only support maximum %d instances for front/primary sensor", atom_instances); return -EINVAL; } ... } 12345678910 12345678910

MTK5.1平台示例：

status_t CamDeviceManagerBase:: openDeviceLocked( hw_device_t** device, hw_module_t const* module, int32_t const i4OpenId, uint32_t device_version ) { ... if ( OK != (status = validateOpenLocked(i4OpenId, device_version)) ) { return status; } ... } status_t CamDeviceManagerImp:: validateOpenLocked(int32_t i4OpenId, uint32_t device_version) const { ... #if !defined(MTKCAM_HAVE_NATIVE_PIP) //MTK平台的ProjectConfig.mk中MTK_CAM_NATIVE_PIP_SUPPORT影响这里宏定义 if ( 0 != mOpenMap.size() ) { MY_LOGE("Not support PIP"); MY_LOGE("[Now] fail to open (deviceId:%d version:0x%x) => failure", i4OpenId, device_version); MY_LOGE("[Previous] (deviceId:%d version:0x%x) mOpenMap.size:%zu", mOpenMap.keyAt(0), mOpenMap.valueAt(0)->uDeviceVersion, mOpenMap.size()); return -EUSERS; } #endif ... } 123456789101112131415161718192021222324252627282930313233 123456789101112131415161718192021222324252627282930313233

PS：  关于Camera HAL的结构体和API支持宏定义都申明在hardware/libhardware/include/hardware/camera_common.h和camera.h文件中.