Agora C++ API Reference for All Platforms

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agora::rtc::IMetadataObserver Class Referenceabstract

## Classes
struct | Metadata

## Public Types
enum | METADATA_TYPE { UNKNOWN_METADATA = -1, VIDEO_METADATA = 0 }
enum | MAX_METADATA_SIZE_TYPE { INVALID_METADATA_SIZE_IN_BYTE = -1, DEFAULT_METADATA_SIZE_IN_BYTE = 512, MAX_METADATA_SIZE_IN_BYTE = 1024 }

## Public Member Functions
virtual | ~IMetadataObserver ()
virtual int | getMaxMetadataSize ()
virtual bool | onReadyToSendMetadata (Metadata &metadata, VIDEO_SOURCE_TYPE source_type)=0
virtual void | onMetadataReceived (const Metadata &metadata)=0

## Detailed Description

Definition of IMetadataObserver

## Member Enumeration Documentation

## ◆ METADATA_TYPE

enum agora::rtc::IMetadataObserver::METADATA_TYPE

The metadata type.

Note
  We only support video metadata for now.

Enumerator
UNKNOWN_METADATA | -1: (Not supported) Unknown.
VIDEO_METADATA | 0: (Supported) Video metadata.

## ◆ MAX_METADATA_SIZE_TYPE

enum agora::rtc::IMetadataObserver::MAX_METADATA_SIZE_TYPE

The maximum metadata size.

Enumerator
INVALID_METADATA_SIZE_IN_BYTE |
DEFAULT_METADATA_SIZE_IN_BYTE |
MAX_METADATA_SIZE_IN_BYTE |

## Constructor & Destructor Documentation

## ◆ ~IMetadataObserver()

virtual agora::rtc::IMetadataObserver::~IMetadataObserver | ( |  | ) |
| inline virtual

## Member Function Documentation

## ◆ getMaxMetadataSize()

virtual int agora::rtc::IMetadataObserver::getMaxMetadataSize | ( |  | ) |
| inline virtual

Occurs when the SDK requests the maximum size of the metadata.

After successfully complete the registration by calling `registerMediaMetadataObserver`, the SDK triggers this callback once every video frame is sent. You need to specify the maximum size of the metadata in the return value of this callback.

Returns
  The maximum size of the buffer of the metadata that you want to use. The highest value is 1024 bytes. Ensure that you set the return value.

## ◆ onReadyToSendMetadata()

virtual bool agora::rtc::IMetadataObserver::onReadyToSendMetadata | ( | Metadata & | metadata,
|  | VIDEO_SOURCE_TYPE | source_type
| ) |  |
| pure virtual

Occurs when the local user receives the metadata.

Note
  Ensure that the size of the metadata does not exceed the value set in the `getMaxMetadataSize` callback.

Parameters

  metadata | The metadata that the user wants to send. For details, see Metadata.
  source_type | The video data type: VIDEO_SOURCE_TYPE.

Returns
  - true: Send.
  - false: Do not send.

## ◆ onMetadataReceived()

virtual void agora::rtc::IMetadataObserver::onMetadataReceived | ( | const Metadata & | metadata | ) |
| pure virtual

Occurs when the local user receives the metadata.

Parameters

  metadata | The metadata received. See Metadata.

Note
  If the receiver is audience, the receiver cannot get the NTP timestamp (ms) that the metadata sends.