高通第三方演算法（單幀資料）新增流程---hal1/hal3
這篇文件寫了很久了，當時腦袋打結用的英文，懶得改成中文了，將就看下，如有錯誤請指正，謝謝
上圖是我總結的高通camera架構。下面介紹怎麼新增單幀的演算法，其實就是對單幀資料進行處理。
Add 3rd algorithm of singleframe：
As we known，camera consists ofthree parts：preview，capture and video。
If we want to Add 3rdalgorithm,we must find out the data callbacked to the HAL that processed by ISP。
callback file：hardware\qcom\camera\QCamera2\HAL\QCamera2HWICallbacks.cpp
Preview/Video callback：
voidQCamera2HardwareInterface::synchronous_stream_cb_routine(
mm_camera_super_buf_t *super_frame,QCameraStream * stream,
void *userdata)
Capture callback:
voidQCamera2HardwareInterface::zsl_channel_cb(mm_camera_super_buf_t*recvd_frame,
void *userdata)
voidQCamera2HardwareInterface::postproc_channel_cb_routine(mm_camera_super_buf_t
The key is the structure mm_camera_super_buf_t,next show the struct of it。
typedef struct {
uint32_t camera_handle;
uint32_tch_id;
uint32_t num_bufs;
uint8_t bUnlockAEC;
uint8_t bReadyForPrepareSnapshot;
mm_camera_buf_def_t* bufs[MAX_STREAM_NUM_IN_BUNDLE];
} mm_camera_super_buf_t;
The buffer is inside in struct mm_camera_buf_def;
typedef struct mm_camera_buf_def {
uint32_t stream_id;
cam_stream_type_t stream_type;
cam_stream_buf_type buf_type;
uint32_t buf_idx;
uint8_t is_uv_subsampled;
struct timespec ts;
uint32_t frame_idx;
union {
mm_camera_plane_buf_def_t planes_buf;
mm_camera_user_buf_def_t user_buf;
};
int fd;
void *buffer;//this stored the data of frame,we shouldoperate it。
size_t frame_len;
void *mem_info;
uint32_t flags;
} mm_camera_buf_def_t;
(Samplecode)Add Face Detection Algorithm:
這裡面的so檔案就是我們的演算法庫，通過dlopen函式對其進行操作。
在最開始需要定義：typedef int (*CAC_FUNC)(unsigned char *data, int width, int height);這個與演算法介面是對應的。
也需要加入標頭檔案：#include “dlfcn.h"
Position：Because realize FaceDetection just need to operate the buffer (one frame)that stored the data inthe forms of YUV420,so we can add Face Detection Algorithm everywhere in the function synchronous_stream_cb_routine。
Add algorithm step by step:
1：Realize FaceDetection。
2：The Face Detection Algorithm depend on opencv lib。Compile it to be a so file (libmy.so) linked with libopencv_java3.so, then it will be private。
3：Push the related lib to the correct dir of your machine。haarcascade_frontalface_alt2.xml---->system/vendor/lib/haarcascade_frontalface_alt2.xml
libopencv_java3.so ---->/system/vendor/lib/libopencv_java3.so
libmy.so ---->/system/vendor/lib/libmy.so
以上是跑的hal1通道，如果跑的hal3通道的話，需要設定hal3 enable。（高通自帶的相機就算開啟hal3也是跑的hal1，應該是不支援hal3的，需另裝apk）
設定命令是：adb shell setprop persist.camera.HAL3.enabled 1
Hal3的回撥檔案是：Qcamera3Channel.cpp
預覽的回撥是在：
voidQCamera3ProcessingChannel::streamCbRoutine(mm_camera_super_buf_t *super_frame,
QCamera3Stream *stream)
拍照的回撥是在：
voidQCamera3PicChannel::streamCbRoutine(mm_camera_super_buf_t *super_frame,
QCamera3Stream*stream)
如上圖所示就是在預覽回撥函式裡面處理buffer，實現預覽變灰的效果。