Android Camera HAL设计初步使用zc301 USB摄像头，这个摄像头返回JPEG图形留，camera的preview需要进行jpeg解码（没做），但是可以直接take jpeg照片。1、修改你的BoardConfig.mkUSE_CAMERA_STUB := false将stub设置为false，在编译时不会编译android2.1/frameworks/base/camera/libcameraservice中的CameraHardwareStub.cppCameraHardwareStub.hFakeCamera.cppFakeCamera.h几个文件2、hardware下建立Camera HAL目录，android2.1/hardware/your board/libcamera复制以上几个文件CameraHardwareStub.cppCameraHardwareStub.hFakeCamera.cppFakeCamera.h可以将其重命名S3C6410CameraHardware.cpp UsbCamera.cpp文件中的Fake和Stub同样可以替换3、编写Android.mk文件LOCAL_PATH:= $(call my-dir) include $(CLEAR_VARS) LOCAL_SRC_FILES:= S3C6410CameraHardware.cpp / UsbCamera.cpp LOCAL_C_INCLUDES := / external/jpeg LOCAL_SHARED_LIBRARIES:= libutils libbinder libui liblog LOCAL_STATIC_LIBRARIES:= / libjpeg LOCAL_MODULE:= libcamera include $(BUILD_SHARED_LIBRARY) 其中jpeg库是为了将来解码jpeg使用的，根据这个脚本可编译出libcamera.so4、修改FakeCamera.cpp->UsbCamera.cpp目前只实现了基本功能该文件可以按照V4L2流程来写网上也有现成的patch，使用mmap方式，可惜是1.6的，没编译过去，待研究1）构造函数中进行初始化UsbCamera::UsbCamera(int width, int height) : mTmpRgb16Buffer(0) { fd = open (DEFAULT_DEVICE, O_RDWR /* required */ | O_NONBLOCK, 0); LOGE("open /dev/video0 fd is %d",fd); ioctl (fd, VIDIOC_QUERYCAP, &cap); CLEAR (fmt); fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; fmt.fmt.pix.width = 640; fmt.fmt.pix.height = 480; fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV; fmt.fmt.pix.field = V4L2_FIELD_INTERLACED; ioctl (fd, VIDIOC_S_FMT, &fmt); length = fmt.fmt.pix.bytesperline * fmt.fmt.pix.height; } 2）获取一帧数据void UsbCamera::getNextFrameAsYuv422(uint8_t *buffer) { LOGE("read to get a pic from camera!"); for (;;) { fd_set fds; struct timeval tv; int r; FD_ZERO (&fds); FD_SET (fd, &fds); /* Timeout. */ tv.tv_sec = 3; tv.tv_usec = 0; r = select (fd + 1, &fds, NULL, NULL, &tv); if (-1 == r) { LOGE ("select"); } if (0 == r) { LOGE ("select timeout/n"); } if (read (fd, buffer, length)); break; } } 3)析构函数UsbCamera::~UsbCamera() { delete[] mTmpRgb16Buffer; close (fd); } 5、修改CameraHardwareStub.cpp->S3C6410CameraHardware.cpp1）改成640x480吧void CameraHardware::initDefaultParameters() { CameraParameters p; p.setPreviewSize(640,480); p.setPreviewFrameRate(1); p.setPreviewFormat("yuv422sp");//("yuv422sp"); p.setPictureSize(640, 480); p.setPictureFormat("jpeg");//("jpeg"); if (setParameters(p) != NO_ERROR) { LOGE("Failed to set default parameters?!"); } } 2）拍照部分要改，因为可以直接获取压缩的jpeg图片int CameraHardware::pictureThread() { UsbCamera* usbCamera = mUsbCamera; if (mMsgEnabled & CAMERA_MSG_SHUTTER) mNotifyCb(CAMERA_MSG_SHUTTER, 0, 0, mCallbackCookie); if (mMsgEnabled & CAMERA_MSG_RAW_IMAGE) { //FIXME: use a canned YUV image! // In the meantime just make another fake camera picture. //int w, h; //mParameters.getPictureSize(&w, &h); //sp<MemoryBase> mem = new MemoryBase(mRawHeap, 0, w * 2 * h); LOGE("CAMERA_MSG_RAW_IMAGE"); //UsbCamera cam(w, h); //cam.getNextFrameAsYuv422((uint8_t *)mRawHeap->base()); //mDataCb(CAMERA_MSG_RAW_IMAGE, mem, mCallbackCookie); } if (mMsgEnabled & CAMERA_MSG_COMPRESSED_IMAGE) { //sp<MemoryHeapBase> heap = new MemoryHeapBase(20000); //sp<MemoryBase> mem = new MemoryBase(heap, 0, 20000); //memcpy(heap->base(), kCannedJpeg, 20000); LOGE("CAMERA_MSG_COMPRESSED_IMAGE"); int w, h; mParameters.getPictureSize(&w, &h); sp<MemoryBase> mem = new MemoryBase(mRawHeap, 0, w * 2 * h); //UsbCamera cam(w, h); usbCamera->getNextFrameAsYuv422((uint8_t *)mRawHeap->base()); mDataCb(CAMERA_MSG_COMPRESSED_IMAGE, mem, mCallbackCookie); } return NO_ERROR; } 3）status_t CameraHardware::setParameters(const CameraParameters& params)有个地方只让take 320x240的pic，要注释掉 /* if (w != 320 && h != 240) { LOGE("Still picture size must be size of canned JPEG (%dx%d)", 320, 240); return -1; }*/ 至此Camera HAL已经可以拍照了。存在问题：1）需要做jpeg->YUV以实现preview功能，libjpeg没用过，暂时不做。2）UsbCamera.cpp要改成V4L2标准流程，现在这种read模式太简单，效率低。
