Camera Kit进阶：C-API实现4K视频录制的参数配置指南

在鸿蒙Next开发中，使用Camera Kit的C-API进行4K视频录制需要对相机设备进行精确的参数配置。本文将详细讲解如何通过C-API实现4K视频录制，并提供部分代码示例。

1. 环境准备

在开始之前，请确保您已经正确配置了开发环境，并安装了支持Camera Kit C-API的相关库和工具链。此外，目标设备必须支持4K分辨率的视频录制功能。

2. 初始化Camera设备

首先，我们需要初始化相机设备并获取其能力列表：

// 初始化Camera Manager
int32_t ret = OHOS_CameraInit();
if (ret != CAMERA_OK) {
    printf("Failed to initialize Camera Manager\n");
    return -1;
}

// 获取Camera设备ID列表
uint32_t cameraIdListSize = 0;
ret = OHOS_GetCameraIdList(NULL, &cameraIdListSize);
if (ret != CAMERA_OK) {
    printf("Failed to get Camera ID list size\n");
    OHOS_CameraDeinit();
    return -1;
}

char **cameraIdList = (char **)malloc(cameraIdListSize * sizeof(char *));
if (!cameraIdList) {
    printf("Memory allocation failed for Camera ID list\n");
    OHOS_CameraDeinit();
    return -1;
}

ret = OHOS_GetCameraIdList(cameraIdList, &cameraIdListSize);
if (ret != CAMERA_OK) {
    printf("Failed to get Camera ID list\n");
    free(cameraIdList);
    OHOS_CameraDeinit();
    return -1;
}

// 打开第一个Camera设备
OHOS_CameraDevice *cameraDevice = NULL;
ret = OHOS_OpenCamera(cameraIdList[0], &cameraDevice);
if (ret != CAMERA_OK) {
    printf("Failed to open Camera device\n");
    free(cameraIdList);
    OHOS_CameraDeinit();
    return -1;
}

3. 配置4K视频录制参数

接下来，我们需要配置相机以支持4K分辨率（3840x2160）的视频录制。这包括设置分辨率、帧率以及编码格式等参数。

// 获取Camera能力
OHOS_CameraAbility *ability = NULL;
ret = OHOS_GetCameraAbility(cameraIdList[0], &ability);
if (ret != CAMERA_OK) {
    printf("Failed to get Camera ability\n");
    OHOS_CloseCamera(cameraDevice);
    free(cameraIdList);
    OHOS_CameraDeinit();
    return -1;
}

// 检查是否支持4K分辨率
bool support4K = false;
for (size_t i = 0; i < ability->videoAbility.size; ++i) {
    if (ability->videoAbility.supportedSizes[i].width == 3840 &&
        ability->videoAbility.supportedSizes[i].height == 2160) {
        support4K = true;
        break;
    }
}

if (!support4K) {
    printf("Camera does not support 4K resolution\n");
    OHOS_ReleaseCameraAbility(ability);
    OHOS_CloseCamera(cameraDevice);
    free(cameraIdList);
    OHOS_CameraDeinit();
    return -1;
}

// 设置4K分辨率
OHOS_CaptureSetting captureSetting;
memset(&captureSetting, 0, sizeof(OHOS_CaptureSetting));
captureSetting.captureMode = CAPTURE_MODE_VIDEO_RECORD;
captureSetting.format = PIXEL_FMT_YUV_420_SP;
captureSetting.size.width = 3840;
captureSetting.size.height = 2160;
captureSetting.frameRate = 30;

ret = OHOS_SetCaptureSettings(cameraDevice, &captureSetting);
if (ret != CAMERA_OK) {
    printf("Failed to set Capture settings\n");
    OHOS_ReleaseCameraAbility(ability);
    OHOS_CloseCamera(cameraDevice);
    free(cameraIdList);
    OHOS_CameraDeinit();
    return -1;
}

// 释放Camera能力
OHOS_ReleaseCameraAbility(ability);

4. 开始和停止视频录制

完成参数配置后，我们可以通过调用相应的API来开始和停止视频录制：

// 创建视频流回调
OHOS_VideoStreamCallback callback;
memset(&callback, 0, sizeof(OHOS_VideoStreamCallback));
callback.onFrameAvailable = [](const uint8_t *data, size_t size, int32_t width, int32_t height) {
    // 处理每一帧数据
    printf("Frame available: size=%zu, width=%d, height=%d\n", size, width, height);
};

// 开始录制
ret = OHOS_StartVideoRecording(cameraDevice, &callback);
if (ret != CAMERA_OK) {
    printf("Failed to start video recording\n");
    OHOS_CloseCamera(cameraDevice);
    free(cameraIdList);
    OHOS_CameraDeinit();
    return -1;
}

printf("Video recording started\n");

// 停止录制
sleep(10); // 录制10秒
ret = OHOS_StopVideoRecording(cameraDevice);
if (ret != CAMERA_OK) {
    printf("Failed to stop video recording\n");
}

printf("Video recording stopped\n");

5. 清理资源

最后，不要忘记清理所有分配的资源：

OHOS_CloseCamera(cameraDevice);
free(cameraIdList);
OHOS_CameraDeinit();

总结

通过上述步骤，您可以使用Camera Kit的C-API在鸿蒙Next设备上实现4K视频录制。请根据实际需求调整参数配置，并确保设备支持所需的分辨率和编码格式。希望本指南对您的开发工作有所帮助。