K230 Multimedia Middleware API Reference

Preface

Overview

This document is written for programmers developing with middleware, providing reference information for multimedia middleware, including APIs, header files, etc.

Target Audience

This document (this guide) is primarily intended for the following personnel:

• Technical Support Engineers

• Software Development Engineers

Abbreviation Definitions

Abbreviation	Description

Revision History

Document Version	Author	Date	Description
V0.1	Software Department	2023.07.20	Initial version

1. Overview

1.1 Overview

The middleware’s position in the system is k230_sdk/src/common/cdk/user/middleware.

This document describes the relevant parts of the middleware, involving intercom protocol, mixing, MP4 format encapsulation and decapsulation, player, etc.

1.2 Function Description

1.2.1 Visual Intercom RTSP Protocol

Referencing the ONVIF RTSP extension, it implements a single-line video visual intercom protocol;

The RTSP server supports sending audio, video, and receiving backchannel audio mediaSubSessions.

The RTSP client supports receiving audio, video, and sending backchannel audio mediaSubSessions.

For related descriptions, see the visual intercom protocol chapter.

1.2.2 Player

Implements MP4 file playback. Video supports H264, H265, and audio supports G711a/u.

1.2.3 Mixing

Implements two-way G711a/u mixing.

1.2.4 MP4 Format Encapsulation and Decapsulation

Implements encapsulation and decapsulation between audio-video and MP4 formats.

2. API Reference

2.1 Visual Intercom RTSP Server

KdRtspServer provides the following APIs:

• Init: Initialization.

• DeInit: Deinitialization.

• CreateSession: Create RTSP session.

• DestroySession: Destroy RTSP session.

• Start: Start RTSP server service.

• Stop: Stop RTSP server service.

• SendVideoData: Write video stream data.

• SendAudioData: Write audio stream data.

2.1.1 KdRtspServer::Init

Description:

RTSP server initialization.

Syntax:

int Init(Port port = 8554, IOnBackChannel *back_channel = nullptr);

Parameters:

Parameter Name	Description	Input/Output
port	RTSP service port.	Input
back_channel	Callback pointer for audio data from the other end.	Input

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: rtsp_server.h

• Library file:

Notes:

None.

Example:

None.

Related Topics:

None.

2.1.2 KdRtspServer::DeInit

Description:

Deinitialization.

Syntax:

void DeInit();

Parameters:

None.

Return Value:

None.

Requirements:

• Header file: rtsp_server.h

• Library file:

Example:

None.

2.1.3 KdRtspServer::CreateSession

Description:

Create RTSP session.

Syntax:

int CreateSession(const std::string &session_name, const SessionAttr &session_attr);

Parameters:

Parameter Name	Description	Input/Output
session_name	Stream URL.	Input
session_attr	Session configuration parameters.	Input

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: rtsp_server.h

• Library file:

Notes:

None.

Example:

None.

2.1.4 KdRtspServer::DestroySession

Description:

Destroy RTSP session.

Syntax:

int DestroySession(const std::string &session_name);

Parameters:

Parameter Name	Description	Input/Output
session_name	Stream URL.	Input

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: rtsp_server.h

• Library file:

Notes:

None.

Example:

None.

Related Topics:

None.

2.1.5 KdRtspServer::Start

Description:

Start RTSP server service.

Syntax:

void Start();

Parameters:

None.

Return Value:

None.

Requirements:

• Header file: rtsp_server.h

• Library file:

Notes:

None.

Example:

None.

Related Topics:

None.

2.1.6 KdRtspServer::Stop

Description:

Stop RTSP server service.

Syntax:

void Stop();

Parameters:

None.

Return Value:

None.

Requirements:

• Header file: rtsp_server.h

• Library file:

Notes:

None.

Example:

None.

2.1.7 KdRtspServer::SendVideoData

Description:

Write video stream data.

Syntax:

int SendVideoData(const std::string &session_name, const uint8_t *data, size_t size, uint64_t timestamp);

Parameters:

Parameter Name	Description	Input/Output
session_name	Stream URL	Input
data	Video stream address.	Input
size	Video stream size.	Input
timestamp	Stream timestamp (milliseconds).	Input

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: rtsp_server.h

• Library file:

Example:

None.

2.1.8 KdRtspServer::SendAudioData

Description:

Write audio stream data.

Syntax:

int SendAudioData(const std::string &session_name, const uint8_t *data, size_t size, uint64_t timestamp);

Parameters:

Parameter Name	Description	Input/Output
session_name	Stream URL	Input
data	Audio stream address.	Input
size	Audio stream size.	Input
timestamp	Stream timestamp (milliseconds).	Input

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: rtsp_server.h

• Library file:

Example:

None.

2.2 Visual Intercom RTSP Client

KdRtspClient module provides the following APIs:

• Init: Initialization.

• DeInit: Deinitialization.

• Open: Open and run RTSP client connection.

• Close: Close RTSP client connection.

• SendAudioData: Write backchannel audio stream data.

2.2.1 KdRtspClient::Init

Description:

Initialization.

Syntax:

int Init(const RtspClientInitParam &param);

Parameters:

Parameter Name	Description	Input/Output
param	RTSP client initialization parameters	Input

class IOnAudioData {
public:
    virtual ~IOnAudioData() {}
    virtual void OnAudioData(const uint8_t *data, size_t size, uint64_t timestamp) = 0;
};

class IOnVideoData {
public:
    enum VideoType {VideoTypeInvalid, VideoTypeH264, VideoTypeH265};
    virtual ~IOnVideoData() {}
    virtual void OnVideoType(VideoType type, uint8_t *extra_data, size_t extra_data_size) = 0;
    virtual void OnVideoData(const uint8_t *data, size_t size, uint64_t timestamp, bool keyframe) = 0;
};

class IRtspClientEvent {
public:
    virtual ~IRtspClientEvent() {}
    virtual void OnRtspClientEvent(int event) = 0; // event 0: shutdown
};

struct RtspClientInitParam {
    IOnVideoData *on_video_data{nullptr}; // Callback for video stream frames received from the server
    IOnAudioData *on_audio_data{nullptr}; // Callback for audio stream frames received from the server
    IRtspClientEvent *on_event{nullptr};  // RTSP client event callback
    bool enableBackchannel{false};        // Whether to enable audio backchannel
};

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: rtsp_client.h

• Library file:

Notes:

None.

Example:

None.

Related Topics:

None.

2.2.2 KdRtspClient::Deinit

Description:

Deinitialization.

Syntax:

void DeInit();

Parameters:

None.

Return Value:

None.

Requirements:

• Header file: rtsp_client.h

• Library file:

Notes:

None.

Example:

None.

Related Topics:

None.

2.2.3 KdRtspClient::Open

Description:

Open and run RTSP client connection.

Syntax:

int Open(const char *url);

Parameters:

Parameter Name	Description	Input/Output
url	RTSP URL.	Input

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: rtsp_client.h

• Library file:

Notes:

None.

Example:

None.

Related Topics:

None.

2.2.4 KdRtspClient::Close

Description:

Close RTSP client.

Syntax:

void Close();

Parameters:

None.

Return Value:

None.

Requirements:

• Header file: rtsp_client.h

• Library file:

Notes:

None.

Example:

None.

Related Topics:

None.

2.2.5 KdRtspClient::SendAudioData

Description:

Write backchannel audio stream data.

Syntax:

int SendAudioData(const uint8_t *data, size_t size, uint64_t timestamp);

Parameters:

Parameter Name	Description	Input/Output
data	Address of audio stream data	Input
size	Size of audio stream data	Input
timestamp	Timestamp of audio stream data (milliseconds)	Input

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: rtsp_client.h

• Library file:

Notes:

None.

Example:

None.

Related Topics:

None.

2.3 Player Encapsulation

KdPlayer module provides the following APIs:

• kd_player_init: Initialization.

• kd_player_deinit: Deinitialization.

• kd_player_setdatasource: Set media playback file.

• kd_player_regcallback: Register event callback.

• kd_player_start: Start playback.

• kd_player_stop: Stop playback.

2.3.1 kd_player_init

Description:

Player initialization.

Syntax:

k_s32 kd_player_init();

Parameters:

None.

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: kplayer.h

• Library file: libkplayer.a

Notes:

None.

Example:

None.

Related Topics:

None.

2.3.2 kd_player_deinit

Description:

Deinitialization.

Syntax:

k_s32 kd_player_deinit();

Parameters:

None.

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: kplayer.h

• Library file: libkplayer.a

Notes:

None.

Example:

None.

Related Topics:

None.

2.3.3 kd_player_setdatasource

Description:

Set media playback file.

Syntax:

k_s32 kd_player_setdatasource(const k_char* filePath);

Parameters:

Parameter Name	Description	Input/Output
filePath	Media file path	Input

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: kplayer.h

• Library file: libkplayer.a

Notes:

None.

Example:

None.

Related Topics:

None.

2.3.4 kd_player_regcallback

Description:

Register player event callback.

Syntax:

k_s32 kd_player_regcallback(K_PLAYER_EVENT_FN pfnCallback, void* pData);

Parameters:

Parameter Name	Description	Input/Output
pfnCallback	Callback function pointer	Input
pData	Callback data pointer	Input

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: kplayer.h

• Library file: libkplayer.a

Notes:

None.

Example:

None.

Related Topics:

None.

2.3.5 kd_player_start

Description:

Start playback.

Syntax:

k_s32 kd_player_start();

Parameters:

None.

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: kplayer.h

• Library file: libkplayer.a

Notes:

None.

Example:

None.

Related Topics:

None.

2.3.6 kd_player_stop

Description:

Stop playback.

Syntax:

k_s32 kd_player_stop();

Parameters:

None.

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: kplayer.h

• Library file: libkplayer.a

Notes:

None.

Example:

None.

Related Topics:

None.

2.4 Audio Mixing

The mixing module provides the following APIs:

• kd_mix_g711a_audio: g711a mixing.

• kd_mix_g711u_audio: g711u mixing.

2.4.1 kd_mix_g711a_audio

Description:

g711a mixing.

Syntax:

k_s32 kd_mix_g711a_audio(k_char *src_data1, k_char *src_data2, k_u32 data_len, k_char *dst_mix_data);

Parameters:

Parameter Name	Description	Input/Output
src_data1	Source data 1	Input
src_data2	Source data 2	Input
data_len	Length of data	Input
dst_mix_data	Mixed result data	Output

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: g711_mix_audio.h

• Library file: libaudio_mix.a

Notes:

None.

Example:

None.

Related Topics:

None.

2.4.2 kd_mix_g711u_audio

Description:

g711u mixing.

Syntax:

k_s32 kd_mix_g711u_audio(k_char *src_data1, k_char *src_data2, k_u32 data_len, k_char *dst_mix_data);

Parameters:

Parameter Name	Description	Input/Output
src_data1	Source data 1	Input
src_data2	Source data 2	Input
data_len	Length of data	Input
dst_mix_data	Mixed result data	Output

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: g711_mix_audio.h

• Library file: libaudio_mix.a

Notes:

None.

Example:

None.

Related Topics:

None.

2.5 MP4 Format Encapsulation and Decapsulation

The MP4 format encapsulation and decapsulation provide the following APIs:

• kd_mp4_create: Create MP4 instance.

• kd_mp4_destroy: Destroy MP4 instance.

• kd_mp4_create_track: Create track for MP4.

• kd_mp4_destroy_tracks: Destroy all tracks for MP4.

• kd_mp4_write_frame: Write frame data to MP4.

• kd_mp4_get_file_info: Get MP4 file information.

• kd_mp4_get_track_by_index: Get track information by index.

• kd_mp4_get_frame: Get track stream information.

2.5.1 kd_mp4_create

Description:

Create MP4 instance.

Syntax:

int kd_mp4_create(KD_HANDLE *mp4_handle, k_mp4_config_s *mp4_cfg);

Parameters:

Parameter Name	Description	Input/Output
mp4_handle	MP4 instance handle	Output
mp4_cfg	Configuration parameters	Input

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: mp4_format.h

• Library file: libmp4.a

Notes:

The configuration information in mp4_cfg can specify whether the created MP4 instance is a muxer or demuxer instance.

Example:

Refer to samples under mp4_muxer and mp4_demuxer.

Related Topics:

None.

2.5.2 kd_mp4_destroy

Description:

Destroy MP4 instance.

Syntax:

int kd_mp4_destroy(KD_HANDLE mp4_handle);

Parameters:

Parameter Name	Description	Input/Output
mp4_handle	MP4 instance handle	Input

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: mp4_format.h

• Library file: libmp4.a

Notes:

None.

Example:

Refer to samples under mp4_muxer and mp4_demuxer.

Related Topics:

None.

2.5.3 kd_mp4_create_track

Description:

Create track for MP4.

Syntax:

int kd_mp4_create_track(KD_HANDLE mp4_handle, KD_HANDLE *track_handle, k_mp4_track_info_s *mp4_track_info);

Parameters:

Parameter Name	Description	Input/Output
mp4_handle	MP4 instance handle	Input
track_handle	Track handle	Output
mp4_track_info	Track configuration	Input

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: mp4_format.h

• Library file: libmp4.a

Notes:

• This API is for muxer. Use when the created MP4 instance is a muxer instance.

• Currently, each MP4 supports creating up to 3 tracks.

Example:

Refer to samples under mp4_muxer.

Related Topics:

None.

2.5.4 kd_mp4_destroy_tracks

Description:

Destroy all tracks for MP4.

Syntax:

int kd_mp4_destroy_tracks(KD_HANDLE mp4_handle);

Parameters:

Parameter Name	Description	Input/Output
mp4_handle	MP4 instance handle	Input

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: mp4_format.h

• Library file: libmp4.a

Notes:

• This API is for muxer. Use when the created MP4 instance is a muxer instance.

• Call this interface after creating the MP4 instance and tracks.

Example:

Refer to samples under mp4_muxer.

Related Topics:

None.

2.5.5 kd_mp4_write_frame

Description:

Write frame data to MP4.

Syntax:

int kd_mp4_write_frame(KD_HANDLE mp4_handle, KD_HANDLE track_handle, k_mp4_frame_data_s *frame_data);

Parameters:

Parameter Name	Description	Input/Output
mp4_handle	MP4 instance handle	Input
track_handle	Track handle	Input
frame_data	Frame data information	Input

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: mp4_format.h

• Library file: libmp4.a

Notes:

• This API is for muxer. Use when the created MP4 instance is a muxer instance.

• Call this interface after creating the MP4 instance and tracks.

Example:

Refer to samples under mp4_muxer.

Related Topics:

None.

2.5.6 kd_mp4_get_file_info

Description:

Get MP4 file information.

Syntax:

int kd_mp4_get_file_info(KD_HANDLE mp4_handle, k_mp4_file_info_s *file_info);

Parameters:

Parameter Name	Description	Input/Output
mp4_handle	MP4 instance handle	Input
file_info	MP4 file information	Output

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: mp4_format.h

• Library file: libmp4.a

Notes:

• This API is for demuxer. Use when the created MP4 instance is a demuxer instance.

Example:

Refer to samples under mp4_demuxer.

Related Topics:

None.

2.5.7 kd_mp4_get_track_by_index

Description:

Get track information by index.

Syntax:

int kd_mp4_get_track_by_index(KD_HANDLE mp4_handle, uint32_t index, k_mp4_track_info_s *mp4_track_info);

Parameters:

Parameter Name	Description	Input/Output
mp4_handle	MP4 instance handle	Input
index	Index	Input
mp4_track_info	Track information	Output

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: mp4_format.h

• Library file: libmp4.a

Notes:

• This API is for demuxer. Use when the created MP4 instance is a demuxer instance.

Example:

Refer to samples under mp4_demuxer.

Related Topics:

None.

2.5.8 kd_mp4_get_frame

Description:

Get track stream information.

Syntax:

int kd_mp4_get_frame(KD_HANDLE mp4_handle, k_mp4_frame_data_s *frame_data);

Parameters:

Parameter Name	Description	Input/Output
mp4_handle	MP4 instance handle	Input
frame_data	Stream information	Output

Return Value:

Return Value	Description
0	Success.
Non-0	Failure.

Requirements:

• Header file: mp4_format.h

• Library file: libmp4.a

Notes:

• This API is for demuxer. Use when the created MP4 instance is a demuxer instance.

Example:

Refer to samples under mp4_demuxer.

Related Topics:

None.