幀元數據是提供在幀的生成期間存在的傳感器配置和/或系統狀態(tài)的快照的一組參數 (或屬性)。在每幀的基礎上重新計算和更新屬性。Orbbec SDK支持查詢(xún)一組預定義屬性，作為最終用戶(hù)可用的幀數據的一部分。

API

在其API中引入了兩個(gè)函數來(lái)查詢(xún)元數據:

C:

/**
 * @brief check if the frame contains the specified metadata
 *
 * @param[in] frame frame object
 * @param[in] type metadata type, refer to @ref ob_frame_metadata_type
 * @param[out] error Log error messages
 */
bool ob_frame_has_metadata(ob_frame *frame, ob_frame_metadata_type type, ob_error **error);

/**
 * @brief Get the metadata value of the frame
 *
 * @param[in] frame frame object
 * @param[in] type  metadata type, refer to @ref ob_frame_metadata_type
 * @param[out] error Log error messages
 * @return int64_t return the metadata value of the frame
 */
int64_t ob_frame_get_metadata_value(ob_frame *frame, ob_frame_metadata_type type, ob_error **error);

C++:

// Member functions of class ob::Frame

/**
* @brief Check if the frame object has metadata of a given type.
*
* @param type The metadata type. refer to @ref OBFrameMetadataType
* @return bool The result.
*/
bool hasMetadata(OBFrameMetadataType type);

/**
* @brief Get the metadata value
*
* @param type The metadata type. refer to @ref OBFrameMetadataType
* @return int64_t The metadata value.
*/
int64_t getMetadataValue(OBFrameMetadataType type);

示例

查詢(xún)元數據屬性的使用模式是 “檢查然后查詢(xún)”

const char *metaDataTypes[] = { "TIMESTAMP", "SENSOR_TIMESTAMP","FRAME_NUMBER",
                                "AUTO_EXPOSURE", "EXPOSURE", "GAIN",
                                "AUTO_WHITE_BALANCE", "WHITE_BALANCE", "BRIGHTNESS",
                                "CONTRAST", "SATURATION", "SHARPNESS",
                                "BACKLIGHT_COMPENSATION", "HUE", "GAMMA",
                                "POWER_LINE_FREQUENCY", "LOW_LIGHT_COMPENSATION", "MANUAL_WHITE_BALANCE",
                                "ACTUAL_FRAME_RATE", "FRAME_RATE",  "AE_ROI_LEFT",
                                "AE_ROI_TOP",  "AE_ROI_RIGHT", "AE_ROI_BOTTOM",
                                "EXPOSURE_PRIORITY", "HDR_SEQUENCE_NAME", "HDR_SEQUENCE_SIZE",
                                "HDR_SEQUENCE_INDEX", "LASER_POWER", "LASER_POWER_MODE",
                                "EMITTER_MODE", "GPIO_INPUT_DATA" };


ob::Pipeline pipe;
pipe.start(nullptr);

auto frameSet = pipe.waitForFrames(100);
auto colorFrame = frameSet->ColorFrame();


for(int metaDataType = 0; metaDataType < OB_FRAME_METADATA_TYPE_COUNT; metaDataType++) {
     // 檢查當前數據幀釋放支持該類(lèi)型元數據
    if(colorFrame->hasMetadata((OBFrameMetadataType)metaDataType)) {
       // 獲取元數據值
       auto value = colorFrame->getMetadataValue((OBFrameMetadataType)metaDataType)
       std::cout << metaDataTypes[metaDataType] << ": " << value << std::endl;
    }
    else {
        std::cout << metaDataTypes[metaDataType] << ": " << "unsupported" << std::endl;
    }
}

在OrbbecViewer中顯示幀元數據

操作系統支持

Windows操作系統  -從windows10開(kāi)始，Microsoft支持元數據提取。有關(guān)詳細信息，請參閱Windows安裝指南。

其他OS - 我們使用libuvc/libusb作為默認后端，它不需要任何操作即可啟用元數據支持。

設備支持

目前，只有Orbbec Gemini 300系列支持這些api。