Camera Recording (C/C++)

As another important function of the camera application, video recording is the process of cyclic frame capture. To smooth video recording, you can follow step 5 in Camera Photographing to set the resolution, flash, focal length, photo quality, and rotation angle.

How to Develop

Read Camera for the API reference.

1. Import the NDK, which provides camera-related attributes and methods.

    // Include the NDK header files.
    #include "hilog/log.h"
    #include "ohcamera/camera.h"
    #include "ohcamera/camera_input.h"
    #include "ohcamera/capture_session.h"
    #include "ohcamera/photo_output.h"
    #include "ohcamera/preview_output.h"
    #include "ohcamera/video_output.h"
    #include "ohcamera/camera_manager.h"
   

2. Link the dynamic library in the CMake script.

    target_link_libraries(entry PUBLIC libohcamera.so libhilog_ndk.z.so)
   

3. Obtain the surface ID.

   Create an AVRecorder instance, and call getInputSurface() of the instance to obtain a surface ID.

4. Create a video output stream.

   Based on the surface ID passed in, obtain the video output streams supported by the current device from videoProfiles in the CameraOutputCapability class. Then, define video recording parameters and use createVideoOutput() to create a video output stream.

    NDKCamera::NDKCamera(char *str)
    {
      Camera_Manager *cameraManager = nullptr;
      Camera_Device* cameras = nullptr;
      Camera_OutputCapability* cameraOutputCapability = nullptr;
      Camera_VideoOutput* videoOutput = nullptr;
      const Camera_VideoProfile* videoProfile;
      uint32_t size = 0;
      uint32_t cameraDeviceIndex = 0;
      char* videoSurfaceId = str;
      Camera_ErrorCode ret = OH_Camera_GetCameraManager(&cameraManager);
      if (cameraManager == nullptr || ret != CAMERA_OK) {
            OH_LOG_ERROR(LOG_APP, "OH_Camera_GetCameraManager failed.");
      }
      ret = OH_CameraManager_GetSupportedCameras(cameraManager, &cameras, &size);
      if (cameras == nullptr || size < 0 || ret != CAMERA_OK) {
          OH_LOG_ERROR(LOG_APP, "OH_CameraManager_GetSupportedCameras failed.");
      }
      ret = OH_CameraManager_GetSupportedCameraOutputCapability(cameraManager, &cameras[cameraDeviceIndex],
                                                                  &cameraOutputCapability);
      if (cameraOutputCapability == nullptr || ret != CAMERA_OK) {
          OH_LOG_ERROR(LOG_APP, "OH_CameraManager_GetSupportedCameraOutputCapability failed.");
      }
      if (cameraOutputCapability->videoProfilesSize < 0) {
        OH_LOG_ERROR(LOG_APP, "videorofilesSize == null");
      }
      videoProfile = cameraOutputCapability->videoProfiles[0];
      // Create a VideoOutput instance.
      ret = OH_CameraManager_CreateVideoOutput(cameraManager, videoProfile, videoSurfaceId, &videoOutput);
      if (videoProfile == nullptr || videoOutput == nullptr || ret != CAMERA_OK) {
          OH_LOG_ERROR(LOG_APP, "OH_CameraManager_CreateVideoOutput failed.");
      }
    }
   

5. Start video recording.

   Call OH_VideoOutput_Start() of the VideoOutput instance to start the video output stream.

      // Start the video output stream.
      ret = OH_VideoOutput_Start(videoOutput);
      if (ret != CAMERA_OK) {
        OH_LOG_ERROR(LOG_APP, "OH_VideoOutput_Start failed.");
      }
   

6. Stop video recording.

   Call OH_VideoOutput_Stop() of the VideoOutput instance to stop the video output stream.

      // Stop the video output stream.
      ret = OH_VideoOutput_Stop(videoOutput);
      if (ret != CAMERA_OK) {
        OH_LOG_ERROR(LOG_APP, "OH_VideoOutput_Stop failed.");
      }
   

Status Listening

During camera application development, you can listen for the status of the video output stream, including recording start, recording end, and video output errors.

• Register the 'frameStart' event to listen for recording start events. This event can be registered when a VideoOutput instance is created and is triggered when the bottom layer starts exposure for recording for the first time. Video recording starts as long as a result is returned.

    ret = OH_VideoOutput_RegisterCallback(videoOutput, GetVideoOutputListener());
    if (ret != CAMERA_OK) {
      OH_LOG_ERROR(LOG_APP, "OH_VideoOutput_RegisterCallback failed.");
    }
  

    void VideoOutputOnFrameStart(Camera_VideoOutput* videoOutput)
    {
        OH_LOG_INFO(LOG_APP, "VideoOutputOnFrameStart");
    }
  
    VideoOutput_Callbacks* GetVideoOutputListener(void)
    {
        static VideoOutput_Callbacks videoOutputListener = {
            .onFrameStart = VideoOutputOnFrameStart,
            .onFrameEnd = VideoOutputOnFrameEnd,
            .onError = VideoOutputOnError
        };
        return &videoOutputListener;
    }
  

• Register the 'frameEnd' event to listen for recording end events. This event can be registered when a VideoOutput instance is created and is triggered when the last frame of recording ends. Video recording ends as long as a result is returned.

    void VideoOutputOnFrameEnd(Camera_VideoOutput* videoOutput, int32_t frameCount)
    {
        OH_LOG_INFO(LOG_APP, "VideoOutput frameCount = %{public}d", frameCount);
    }
  

• Register the 'error' event to listen for video output errors. The callback function returns an error code when an API is incorrectly used. For details about the error code types, see Camera_ErrorCode.

    void VideoOutputOnError(Camera_VideoOutput* videoOutput, Camera_ErrorCode errorCode)
    {
        OH_LOG_INFO(LOG_APP, "VideoOutput errorCode = %{public}d", errorCode);
    }