目录

前言

一、HIDL接口

1.CameraProvier

1.setCallback(ICameraProviderCallback callback)

2.getVendorTags

3.getCameraIdList

4.isSetTorchModeSupported

5.getCameraDeviceInterface_V3_x

2.CameraDevice

1.getResourceCost

2. getCameraCharacteristics

3.setTorchMode

4.open

5.dumpState

3.CameraDeviceSession

1.constructDefaultRequestSettings

2.configureStreams

3.processCaptureRequest

4.getCaptureRequestMetadataQueue

5.getCaptureResultMetadataQueue

6.flush

7.close

二、HAL实现

前言

本文主要介绍google原生HAL service

一、HIDL接口

代码路径：

http://androidxref.com/9.0.0_r3/xref/hardware/interfaces/camera/provider/2.4/

1.CameraProvier

1.setCallback(ICameraProviderCallback callback)

framework将回调函数设置给HAL，HAL可以通过这些回调函数将一些信息异步回给framework，包括两个回调函数：

cameraDeviceStatusChange(string cameraDeviceName, CameraDeviceStatus newStatus)
torchModeStatusChange(string cameraDeviceName, TorchModeStatus newStatus)

CameraDeviceStatus和TorchModeStatus定义

2.getVendorTags

3.getCameraIdList

4.isSetTorchModeSupported

5.getCameraDeviceInterface_V3_x

getCameraDeviceInterface_V3_x(string cameraDeviceName) generates (Status status,android.hardware.camera.device@3.2::ICameraDevice device);

通过该接口返回ICameraDevice

2.CameraDevice

1.getResourceCost

2. getCameraCharacteristics

3.setTorchMode

手电筒应用通过该接口控制Torch开关；当手电筒打开了，这时如果打开了相机手电筒会关闭，这个关闭不是手电筒通过该接口关闭的，而是camera HAL判断当前如果打开了torch就关闭了。

4.open

open(ICameraDeviceCallback callback) generates(Status status, ICameraDeviceSession session);

framework将CameraDeviceCallback回调函数下发下来，同时获取CameraDeviceSession接口

CameraDeviceCallback接口：

processCaptureResult(vec<CaptureResult> results);
notify(vec<NotifyMsg> msgs);

http://androidxref.com/9.0.0_r3/xref/hardware/libhardware/include/hardware/camera3.h

2354 * Applications will also receive these partial results immediately, so sending
2355 * partial results is a highly recommended performance optimization to avoid
2356 * the total pipeline latency before sending the results for what is known very
2357 * early on in the pipeline.
2358 *
2359 * A typical use case might be calculating the AF state halfway through the
2360 * pipeline; by sending the state back to the framework immediately, we get a
2361 * 50% performance increase and perceived responsiveness of the auto-focus

该函数可以被调用多次，包括多次metadata和buffer，partial metadata可以减少pipeline latency，pipeline latency的result delay的次数最大为底层的max buffer个数。

partial metadata的使用有很多约束，要按照规范使用

5.dumpState

3.CameraDeviceSession

1.constructDefaultRequestSettings

2.configureStreams

stream包括Camera3InputStream和Camera3OutputStream，Camera3OutputStream是HAL填充，Camera3InputStream是应用将流程中前面request获取到的YUV out再当做YUV input传下来让HAL来refine，结果输出到同一个request里配置的out里。可以参考CTS里的xref: /cts/tests/camera/src/android/hardware/camera2/cts/ReprocessCaptureTest.java里的流程，configure_stream的时候配置三路流，一路input yuv，一路output yuv，一路output jpg，然后是下request阶段，第一个请求先下一路output yuv，应用拿到output yuv，第二个请求下一路intput yuv和一路jpeg，尺寸可以不一样，HAL将这个yuv过一遍offline pipeline之后再jpeg编码，最后hal需要将input yuv和jpeg都要还回去，另外说明的一点是第一个请求不过offline pipeline直接送上去，第二个请求跳过online pipeline

如何在camera2 API中使用reprocessCaptureRequest - IT屋-程序员软件开发技术分享社区

Android Camera 原理之拍照流程zsl优化方案 - 简书

这里面用input stream实现zsl，这当然是从应用的角度实现zsl的一种方法

3.processCaptureRequest

4.getCaptureRequestMetadataQueue

5.getCaptureResultMetadataQueue

6.flush

7.close

二、HAL实现

google默认hal实现

google使用hal规范实现camera hal，HAL hidl化之后其实不再需要使用之前的hal规范，只要按照hidl接口实现即可

1.注册HAL Module

static int open_dev(const hw_module_t* module,
208                    const char* name,
209                    hw_device_t** device) {
210  return gCameraHAL.openDevice(module, name, device);
211}
212
213}  // namespace v4l2_camera_hal
214
215static hw_module_methods_t v4l2_module_methods = {
216    .open = v4l2_camera_hal::open_dev};
217
218camera_module_t HAL_MODULE_INFO_SYM __attribute__((visibility("default"))) = {
219    .common =
220        {
221            .tag = HARDWARE_MODULE_TAG,
222            .module_api_version = CAMERA_MODULE_API_VERSION_2_4,
223            .hal_api_version = HARDWARE_HAL_API_VERSION,
224            .id = CAMERA_HARDWARE_MODULE_ID,
225            .name = "V4L2 Camera HAL v3",
226            .author = "The Android Open Source Project",
227            .methods = &v4l2_module_methods,
228            .dso = nullptr,
229            .reserved = {0},
230        },
231    .get_number_of_cameras = v4l2_camera_hal::get_number_of_cameras,
232    .get_camera_info = v4l2_camera_hal::get_camera_info,
233    .set_callbacks = v4l2_camera_hal::set_callbacks,
234    .get_vendor_tag_ops = v4l2_camera_hal::get_vendor_tag_ops,
235    .open_legacy = v4l2_camera_hal::open_legacy,
236    .set_torch_mode = v4l2_camera_hal::set_torch_mode,
237    .init = nullptr,
238    .reserved = {nullptr, nullptr, nullptr, nullptr, nullptr}};

2.通过method里的open接口获取camera3_device

33typedef struct camera3_device {
3234    /**
3235     * common.version must equal CAMERA_DEVICE_API_VERSION_3_0 to identify this
3236     * device as implementing version 3.0 of the camera device HAL.
3237     *
3238     * Performance requirements:
3239     *
3240     * Camera open (common.module->common.methods->open) should return in 200ms, and must return
3241     * in 500ms.
3242     * Camera close (common.close) should return in 200ms, and must return in 500ms.
3243     *
3244     */
3245    hw_device_t common;
3246    camera3_device_ops_t *ops;
3247    void *priv;
3248} camera3_device_t;

Camera HAL Service流程总结相关推荐

Camera HAL 参数传递流程 ---- 以ANDROID_CONTROL_AE_EXPOSURE_COMPENSATION为例追踪
CameraApp里面用户操作的设置项分为两类: 一类由App自行处理,比如照片保存路径.绘制九宫格参照线.拍照声音等等一类需要经由framework下发到hal,然后进一步流转到相应的算法库中去处 ...
【Mtk Camera Hal到驱动的流程（1）】
Mtk Camera Hal到驱动的流程(1) (1)架构介绍 (A)Camera 的框架分为 Kernel 部分和 Hal 部分 Kernel部分: image sensor driver -- 负 ...
Android4.2之Camera系统HAL调用流程
一.重要结构体 1.模块 hardware/libhardware/include/hardware/camera_common.h [cpp] view plaincopy typedef stru ...
Android Camera open运行流程
Android Camera 运行流程一首先既然Camera是利用binder通信,它肯定要将它的service注册到ServiceManager里面,以备后续Client引用,那么这一步是在哪里 ...
android_驱动_qcom_【高通SDM660平台】(4) --- Camera Init 初始化流程
[高通SDM660平台]Camera Init 初始化流程一.Camera 系统架构二.Camera Init 初始化流程 2.1 CameraService 启动 2.2 CameraServi ...
android8 Camera2 从 CameraService 到 HAL Service
上回讲到,在 CameraService::makeClient 中,实例化了一个 CameraDeviceClient.现在我们就从它的构造函数开始,继续探索打开相机的流程. 这一部分主要活动在 R ...
Android Camera 五 Camera HAL v1
Android Camera 一源码路径 Android Camera 二 JNI JAVA和C/CPP图像数据传输流程分析 Android Camera 三 CameraService 和 Cli ...
Android Camera HAL3 - 框架流程预览
前面说了 HAL3 是一个总线型的设计结构,本文就先对 HAL3 的控制流进行一个提纲挈领式的概述,主要理解整个 HAL3 的主干框架,以便对后续深入各个细节. 主干流程以下全部都是摘抄 Googl ...
android mtk camera startpreview,android8.1 mtk camera hal各种操作流程
最近一年,一直在做android上的视频编解码和录相.以及camera hal和系统框架这一块.随着做的慢慢的深入,越发觉得mtk的camera hal这一块,有其独到之处.偏偏网上相关的资料却是极少 ...

Camera HAL Service流程总结

前言