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WebRTC API Manual

Overview

libpeer is a lightweight WebRTC library implemented in pure C. It provides PeerConnection management, SDP signaling exchange, ICE connectivity, DataChannel communication, and audio and video data transmission and reception. The APIs documented in this guide are C-language interfaces that can be called from C or C++ applications, compiled into executables, and run on the k230 development board.

Note:

1、The currently supported video codecs are H.264 and H.265; VP8 and MJPEG are not yet implemented; 2、The currently supported audio codecs are G711A (PCMA), G711U (PCMU), and OPUS; 3、peer_init must be called to initialize libsrtp and SCTP before calling peer_connection_create; 4、Signaling exchange requires the peer_signaling module or a custom signaling service; 5、When sending video data, complete NAL units must be provided; when sending audio data, G711 or OPUS encoded frames must be provided.

Supported Media Codecs

Type	Codec Format	Remarks
Video	H.264
Video	H.265
Video	VP8	Not yet implemented
Video	MJPEG	Not yet implemented
Audio	G711A	PCMA
Audio	G711U	PCMU
Audio	OPUS

Parameter Type Introduction

SdpType

【Description】

SdpType is used to identify the type of SDP (Session Description Protocol), which is divided into Offer and Answer.

【Definition】

typedef enum SdpType {
  SDP_TYPE_OFFER = 0,
  SDP_TYPE_ANSWER,
} SdpType;

【Description】

Enumeration Value	Description
SDP_TYPE_OFFER	SDP Offer, created by the caller
SDP_TYPE_ANSWER	SDP Answer, created by the responder

PeerConnectionState

【Description】

PeerConnectionState is used to represent the ICE connection state of a PeerConnection.

【Definition】

typedef enum PeerConnectionState {
  PEER_CONNECTION_CLOSED = 0,
  PEER_CONNECTION_NEW,
  PEER_CONNECTION_CHECKING,
  PEER_CONNECTION_CONNECTED,
  PEER_CONNECTION_COMPLETED,
  PEER_CONNECTION_FAILED,
  PEER_CONNECTION_DISCONNECTED,
} PeerConnectionState;

【Description】

Enumeration Value	Description
PEER_CONNECTION_CLOSED	The connection has been closed
PEER_CONNECTION_NEW	New connection; the ICE agent is gathering candidates
PEER_CONNECTION_CHECKING	The ICE agent is checking candidate pairs
PEER_CONNECTION_CONNECTED	At least one candidate pair has connected successfully
PEER_CONNECTION_COMPLETED	The ICE agent has completed checking
PEER_CONNECTION_FAILED	The ICE connection failed
PEER_CONNECTION_DISCONNECTED	The connection has been disconnected

DataChannelType

【Description】

DataChannelType is used to identify the type of data transmitted by a DataChannel.

【Definition】

typedef enum DataChannelType {
  DATA_CHANNEL_NONE = 0,
  DATA_CHANNEL_STRING,
  DATA_CHANNEL_BINARY,
} DataChannelType;

【Description】

Enumeration Value	Description
DATA_CHANNEL_NONE	No DataChannel
DATA_CHANNEL_STRING	String data
DATA_CHANNEL_BINARY	Binary data

DecpChannelType

【Description】

DecpChannelType is used to configure the reliability and ordering policies of a DataChannel, corresponding to the channel types in DCEP (Data Channel Establishment Protocol).

【Definition】

typedef enum DecpChannelType {
  DATA_CHANNEL_RELIABLE = 0x00,
  DATA_CHANNEL_RELIABLE_UNORDERED = 0x80,
  DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT = 0x01,
  DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT_UNORDERED = 0x81,
  DATA_CHANNEL_PARTIAL_RELIABLE_TIMED = 0x02,
  DATA_CHANNEL_PARTIAL_RELIABLE_TIMED_UNORDERED = 0x82,
} DecpChannelType;

【Description】

Enumeration Value	Description
DATA_CHANNEL_RELIABLE	Reliable, ordered transmission
DATA_CHANNEL_RELIABLE_UNORDERED	Reliable, unordered transmission
DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT	Partially reliable, guaranteed based on the number of retransmissions
DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT_UNORDERED	Partially reliable and unordered, guaranteed based on the number of retransmissions
DATA_CHANNEL_PARTIAL_RELIABLE_TIMED	Partially reliable, guaranteed based on the timeout duration
DATA_CHANNEL_PARTIAL_RELIABLE_TIMED_UNORDERED	Partially reliable and unordered, guaranteed based on the timeout duration

MediaCodec

【Description】

MediaCodec is used to configure the audio and video encoding formats.

【Definition】

typedef enum MediaCodec {
  CODEC_NONE = 0,

  /* Video */
  CODEC_H264,
  CODEC_H265,
  CODEC_VP8,    // not implemented yet
  CODEC_MJPEG,  // not implemented yet

  /* Audio */
  CODEC_OPUS,
  CODEC_PCMA,
  CODEC_PCMU,
} MediaCodec;

【Description】

Enumeration Value	Description
CODEC_NONE	No encoding
CODEC_H264	H.264 video encoding
CODEC_H265	H.265 video encoding
CODEC_VP8	VP8 video encoding (not implemented)
CODEC_MJPEG	MJPEG video encoding (not implemented)
CODEC_OPUS	OPUS audio encoding
CODEC_PCMA	G711A audio encoding
CODEC_PCMU	G711U audio encoding

IceServer

【Description】

IceServer is used to configure ICE (Interactive Connectivity Establishment) server information for NAT traversal.

【Definition】

typedef struct IceServer {
  const char* urls;
  const char* username;
  const char* credential;
} IceServer;

【Parameters】

Name	Type	Description
urls	const char*	ICE server URL, such as “stun:stun.l.google.com:19302”
username	const char*	TURN server username; may be NULL for STUN servers
credential	const char*	TURN server credential; may be NULL for STUN servers

【Example】

IceServer server = {
    .urls = "stun:stun.l.google.com:19302",
    .username = NULL,
    .credential = NULL
};

PeerConfiguration

【Description】

PeerConfiguration is used to configure PeerConnection parameters, including the ICE server list, audio and video encoding formats, DataChannel type, and audio and video data callbacks.

【Definition】

typedef struct PeerConfiguration {
  IceServer ice_servers[5];

  MediaCodec audio_codec;
  MediaCodec video_codec;
  DataChannelType datachannel;

  void (*onaudiotrack)(uint8_t* data, size_t size, void* userdata);
  void (*onvideotrack)(uint8_t* data, size_t size, void* userdata);
  void (*on_request_keyframe)(void* userdata);
  void* user_data;
} PeerConfiguration;

【Parameters】

Name	Type	Description
ice_servers	IceServer[5]	ICE server list, with a maximum of 5
audio_codec	MediaCodec	Audio encoding format
video_codec	MediaCodec	Video encoding format
datachannel	DataChannelType	DataChannel data type
onaudiotrack	Function pointer	Callback function for receiving remote audio data
onvideotrack	Function pointer	Callback function for receiving remote video data
on_request_keyframe	Function pointer	Callback function for requesting a keyframe
user_data	void*	User data pointer passed to the callback function

【Example】

PeerConfiguration config = {0};
config.ice_servers[0] = (IceServer){ "stun:stun.l.google.com:19302", NULL, NULL };
config.audio_codec = CODEC_PCMU;
config.video_codec = CODEC_H264;
config.datachannel = DATA_CHANNEL_NONE;
config.onaudiotrack = NULL;
config.onvideotrack = NULL;
config.on_request_keyframe = NULL;
config.user_data = NULL;

API Introduction

peer_init

【Description】

Initializes the WebRTC library, including the libsrtp and SCTP protocol stacks. This function must be called before using any PeerConnection-related APIs.

【Definition】

int peer_init();

【Parameters】

None.

【Return Value】

Return Value	Description
0	Success
-1	Failure, libsrtp initialization failed

【Example】

if (peer_init() != 0) {
    printf("WebRTC init failed\n");
    return -1;
}

peer_deinit

【Description】

Deinitializes the WebRTC library and releases resources related to the libsrtp and SCTP protocol stacks.

【Definition】

void peer_deinit();

【Parameters】

None.

【Return Value】

None.

【Example】

peer_deinit();

peer_connection_create

【Description】

Creates a PeerConnection instance.

【Definition】

PeerConnection* peer_connection_create(PeerConfiguration* config);

【Parameters】

Name	Type	Description
config	PeerConfiguration*	PeerConnection configuration

【Return Value】

Return Value	Description
PeerConnection*	Success, returns the instance pointer
NULL	Failure

【Example】

PeerConnection* pc = peer_connection_create(&config);
if (!pc) {
    printf("Create peer connection failed\n");
    return -1;
}

peer_connection_destroy

【Description】

Destroys a PeerConnection instance and releases related resources.

【Definition】

void peer_connection_destroy(PeerConnection* pc);

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance

【Return Value】

None.

【Example】

peer_connection_destroy(pc);

peer_connection_close

【Description】

Closes the PeerConnection connection without releasing resources. To release resources, call peer_connection_destroy.

【Definition】

void peer_connection_close(PeerConnection* pc);

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance

【Return Value】

None.

peer_connection_get_state

【Description】

Gets the current connection state of the PeerConnection.

【Definition】

PeerConnectionState peer_connection_get_state(PeerConnection* pc);

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance

【Return Value】

Return Value	Description
PeerConnectionState	Current connection state

【Example】

PeerConnectionState state = peer_connection_get_state(pc);
printf("Connection state: %s\n", peer_connection_state_to_string(state));

peer_connection_state_to_string

【Description】

Converts a PeerConnectionState enum value into a readable string.

【Definition】

const char* peer_connection_state_to_string(PeerConnectionState state);

【Parameters】

Name	Type	Description
state	PeerConnectionState	Connection state enum

【Return Value】

Return Value	Description
const char*	String description corresponding to the state

peer_connection_create_offer

【Description】

Creates an SDP Offer for initiating a WebRTC connection. Typically called by the caller.

【Definition】

const char* peer_connection_create_offer(PeerConnection* pc);

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance

【Return Value】

Return Value	Description
const char*	SDP Offer string
NULL	Failure

【Example】

const char* offer = peer_connection_create_offer(pc);
if (offer) {
    printf("SDP Offer:\n%s\n", offer);
}

peer_connection_create_answer

【Description】

Creates an SDP Answer for responding to a WebRTC connection. Typically called by the answerer after receiving an Offer.

【Definition】

const char* peer_connection_create_answer(PeerConnection* pc);

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance

【Return Value】

Return Value	Description
const char*	SDP Answer string
NULL	Failure

peer_connection_set_local_description

【Description】

Sets the local SDP description.

【Definition】

void peer_connection_set_local_description(PeerConnection* pc, const char* sdp, SdpType sdp_type);

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance
sdp	const char*	SDP string
sdp_type	SdpType	SDP type (Offer or Answer)

【Return Value】

None.

peer_connection_set_remote_description

【Description】

Sets the remote SDP description.

【Definition】

void peer_connection_set_remote_description(PeerConnection* pc, const char* sdp, SdpType sdp_type);

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance
sdp	const char*	Remote SDP string
sdp_type	SdpType	SDP type (Offer or Answer)

【Return Value】

None.

【Example】

// The answerer sets the remote description after receiving the Offer
peer_connection_set_remote_description(pc, remote_offer_sdp, SDP_TYPE_OFFER);
// Create the Answer
const char* answer = peer_connection_create_answer(pc);
// Set the local description
peer_connection_set_local_description(pc, answer, SDP_TYPE_ANSWER);

peer_connection_add_ice_candidate

【Description】

Adds a remote ICE candidate to the PeerConnection.

【Definition】

int peer_connection_add_ice_candidate(PeerConnection* pc, char* ice_candidate);

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance
ice_candidate	char*	ICE candidate string

【Return Value】

Return Value	Description
0	Success
-1	Failure

peer_connection_onicecandidate

【Description】

Registers an ICE candidate event callback function. This callback is triggered when a local ICE candidate is discovered. The callback parameters contain the complete SDP text.

【Definition】

void peer_connection_onicecandidate(PeerConnection* pc, void (*onicecandidate)(char* sdp_text, void* userdata));

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance
onicecandidate	Function pointer	ICE candidate callback function

Callback function parameters:

Parameter	Type	Description
sdp_text	char*	SDP text containing the ICE candidate

peer_connection_oniceconnectionstatechange

【Description】

Registers an ICE connection state change event callback function. This callback is triggered when the ICE connection state changes.

【Definition】

void peer_connection_oniceconnectionstatechange(PeerConnection* pc,
    void (*oniceconnectionstatechange)(PeerConnectionState state, void* userdata));

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance
oniceconnectionstatechange	Function pointer	ICE connection state change callback function

Callback function parameters:

Parameter	Type	Description
state	PeerConnectionState	Current connection state

【Example】

void on_ice_state_change(PeerConnectionState state, void* userdata) {
    printf("ICE state: %s\n", peer_connection_state_to_string(state));
}

peer_connection_oniceconnectionstatechange(pc, on_ice_state_change);

peer_connection_on_receiver_packet_loss

【Description】

Registers an RTCP receiver packet loss rate callback function. This callback is triggered when an RTCP receiver report is received.

【Definition】

void peer_connection_on_receiver_packet_loss(PeerConnection* pc,
    void (*on_receiver_packet_loss)(float fraction_loss, uint32_t total_loss, void* userdata));

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance
on_receiver_packet_loss	Function pointer	Packet loss rate callback function

Callback function parameters:

Parameter	Type	Description
fraction_loss	float	Packet loss rate (0.0~1.0)
total_loss	uint32_t	Cumulative number of lost packets

peer_connection_send_video

【Description】

Sends video frame data through the PeerConnection.

【Definition】

int peer_connection_send_video(PeerConnection* pc, const uint8_t* packet, size_t bytes, uint64_t timestamp_us);

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance
packet	const uint8_t*	Video frame data pointer (NAL unit)
bytes	size_t	Video frame data size (bytes)
timestamp_us	uint64_t	Timestamp (microseconds)

【Return Value】

Return Value	Description
0	Success
-1	Failure

【Example】

peer_connection_send_video(pc, nal_data, nal_size, timestamp_us);

peer_connection_send_audio

【Description】

Sends audio frame data through the PeerConnection.

【Definition】

int peer_connection_send_audio(PeerConnection* pc, const uint8_t* packet, size_t bytes, uint64_t timestamp_us);

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance
packet	const uint8_t*	Audio frame data pointer (G711 or OPUS encoded frame)
bytes	size_t	Audio frame data size (bytes)
timestamp_us	uint64_t	Timestamp (microseconds)

【Return Value】

Return Value	Description
0	Success
-1	Failure

【Example】

peer_connection_send_audio(pc, g711_frame, frame_size, timestamp_us);

peer_connection_create_datachannel

【Description】

Creates a DataChannel channel.

【Definition】

int peer_connection_create_datachannel(PeerConnection* pc, DecpChannelType channel_type,
    uint16_t priority, uint32_t reliability_parameter, char* label, char* protocol);

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance
channel_type	DecpChannelType	Channel reliability and ordering policy
priority	uint16_t	Channel priority
reliability_parameter	uint32_t	Reliability parameter (retransmission count or timeout, depending on channel_type)
label	char*	Channel label name
protocol	char*	Subprotocol name; may be an empty string

【Return Value】

Return Value	Description
0	Success
-1	Failure

【Example】

// Create a reliable, ordered DataChannel
peer_connection_create_datachannel(pc, DATA_CHANNEL_RELIABLE, 0, 0, "my_channel", "");

peer_connection_create_datachannel_sid

【Description】

Creates a DataChannel channel with the specified Stream ID.

【Definition】

int peer_connection_create_datachannel_sid(PeerConnection* pc, DecpChannelType channel_type,
    uint16_t priority, uint32_t reliability_parameter, char* label, char* protocol, uint16_t sid);

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance
channel_type	DecpChannelType	Channel reliability and ordering policy
priority	uint16_t	Channel priority
reliability_parameter	uint32_t	Reliability parameter
label	char*	Channel label name
protocol	char*	Subprotocol name
sid	uint16_t	Specified Stream ID

【Return Value】

Return Value	Description
0	Success
-1	Failure

peer_connection_datachannel_send

【Description】

Sends a text message through the DataChannel.

【Definition】

int peer_connection_datachannel_send(PeerConnection* pc, char* message, size_t len);

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance
message	char*	Message content
len	size_t	Message length

【Return Value】

Return Value	Description
0	Success
-1	Failure

peer_connection_datachannel_send_sid

【Description】

Sends a text message through the DataChannel with the specified Stream ID.

【Definition】

int peer_connection_datachannel_send_sid(PeerConnection* pc, char* message, size_t len, uint16_t sid);

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance
message	char*	Message content
len	size_t	Message length
sid	uint16_t	Stream ID

【Return Value】

Return Value	Description
0	Success
-1	Failure

peer_connection_datachannel_send_binary

【Description】

Sends binary data through the DataChannel (PPID=53).

【Definition】

int peer_connection_datachannel_send_binary(PeerConnection* pc, const char* data, size_t len);

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance
data	const char*	Binary data pointer
len	size_t	Data length

【Return Value】

Return Value	Description
0	Success
-1	Failure

peer_connection_datachannel_send_binary_sid

【Description】

Sends binary data through the DataChannel with the specified Stream ID (PPID=53).

【Definition】

int peer_connection_datachannel_send_binary_sid(PeerConnection* pc, const char* data, size_t len, uint16_t sid);

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance
data	const char*	Binary data pointer
len	size_t	Data length
sid	uint16_t	Stream ID

【Return Value】

Return Value	Description
0	Success
-1	Failure

peer_connection_ondatachannel

【Description】

Registers DataChannel event callback functions, including message reception, channel opening, and channel closing events.

【Definition】

void peer_connection_ondatachannel(PeerConnection* pc,
    void (*onmessage)(char* msg, size_t len, void* userdata, uint16_t sid),
    void (*onopen)(void* userdata),
    void (*onclose)(void* userdata));

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance
onmessage	Function pointer	Message reception callback function
onopen	Function pointer	Channel opening callback function
onclose	Function pointer	Channel closing callback function

onmessage callback parameters:

Parameter	Type	Description
msg	char*	Message content
len	size_t	Message length
sid	uint16_t	Stream ID

【Example】

void on_dc_message(char* msg, size_t len, void* userdata, uint16_t sid) {
    printf("DataChannel message (sid=%u): %.*s\n", sid, (int)len, msg);
}

void on_dc_open(void* userdata) {
    printf("DataChannel opened\n");
}

void on_dc_close(void* userdata) {
    printf("DataChannel closed\n");
}

peer_connection_ondatachannel(pc, on_dc_message, on_dc_open, on_dc_close);

peer_connection_lookup_sid

【Description】

Looks up the corresponding Stream ID by channel label name.

【Definition】

int peer_connection_lookup_sid(PeerConnection* pc, const char* label, uint16_t* sid);

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance
label	const char*	Channel label name
sid	uint16_t*	Output: the found Stream ID

【Return Value】

Return Value	Description
0	Successfully found
-1	Not found

peer_connection_lookup_sid_label

【Description】

Looks up the corresponding channel label name by Stream ID.

【Definition】

char* peer_connection_lookup_sid_label(PeerConnection* pc, uint16_t sid);

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance
sid	uint16_t	Stream ID

【Return Value】

Return Value	Description
char*	Channel label name string
NULL	Not found

peer_connection_loop

【Description】

Runs the PeerConnection event loop to process underlying events such as ICE and DTLS. Typically called repeatedly in a separate thread.

【Definition】

int peer_connection_loop(PeerConnection* pc);

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance

【Return Value】

Return Value	Description
0	Normal exit
-1	Error

peer_connection_get_sctp

【Description】

Gets the pointer to the SCTP instance associated with the PeerConnection.

【Definition】

void* peer_connection_get_sctp(PeerConnection* pc);

【Parameters】

Name	Type	Description
pc	PeerConnection*	PeerConnection instance

【Return Value】

Return Value	Description
void*	SCTP instance pointer
NULL	No SCTP instance

Signaling API Overview

peer_signaling_connect

【Description】

Connects to the signaling server and establishes a signaling channel. Supports HTTP and MQTT signaling protocols.

【Definition】

int peer_signaling_connect(const char* url, const char* token, PeerConnection* pc);

【Parameters】

Name	Type	Description
url	const char*	Signaling server URL
token	const char*	Authentication token; may be NULL
pc	PeerConnection*	Associated PeerConnection instance

【Return Value】

Return Value	Description
0	Success
-1	Failure

【Example】

int ret = peer_signaling_connect("http://192.168.1.100:8080", NULL, pc);
if (ret != 0) {
    printf("Signaling connect failed\n");
}

peer_signaling_disconnect

【Description】

Disconnects from the signaling server.

【Definition】

void peer_signaling_disconnect();

【Parameters】

None.

【Return Value】

None.

peer_signaling_loop

【Description】

Runs the signaling event loop and processes signaling messages. Usually called repeatedly in a separate thread.

【Definition】

int peer_signaling_loop();

【Parameters】

None.

【Return Value】

Return Value	Description
0	Normal exit
-1	Error

peer_signaling_set_custom_rpc_handler

【Description】

Registers a custom RPC method callback for handling application-layer RPC methods not recognized by the signaling layer. Must be called after peer_signaling_connect. Only one handler can be registered at a time; subsequent calls replace the previous handler.

【Definition】

void peer_signaling_set_custom_rpc_handler(peer_signaling_custom_rpc_cb cb, void* userdata);

【Parameters】

Name	Type	Description
cb	peer_signaling_custom_rpc_cb	Callback function for custom RPC method handling
userdata	void*	User data pointer passed to the callback function

Callback function signature:

typedef int (*peer_signaling_custom_rpc_cb)(const char* method, cJSON* params, int id,
                                            cJSON** result, cJSON** error, void* userdata);

Callback parameter descriptions:

Parameter	Type	Description
method	const char*	RPC method name
params	cJSON*	Request parameter JSON object; may be NULL
id	int	JSON-RPC request ID
result	cJSON**	Output: set the result JSON object (caller takes ownership)
error	cJSON**	Output: set the error JSON object (caller takes ownership)
userdata	void*	User data pointer

Callback return value:

Return Value	Description
0	Method handled (result or error must be set)
-1	Method not handled (the signaling layer will return METHOD_NOT_FOUND)

peer_signaling_publish

【Description】

Publishes a message to the specified topic through the signaling layer’s MQTT connection. Effective only in MQTT mode (proto == 0); returns -1 in HTTP mode or when the MQTT connection has not been established.

【Definition】

int peer_signaling_publish(const char* topic, const char* message);

【Parameters】

Name	Type	Description
topic	const char*	MQTT topic, e.g. “/devices/heartbeat”
message	const char*	Message content (JSON string)

【Return Value】

Return Value	Description
0	Success
-1	Failure; HTTP mode or MQTT connection not established

Example

The following example is written in C++ and demonstrates typical usage of the libpeer C API in a C++ project. The event loop uses std::thread to run in a separate thread.

#include "peer.h"
#include "peer_connection.h"
#include "peer_signaling.h"
#include <stdio.h>
#include <string.h>
#include <thread>

static int running = 1;

void on_ice_candidate(char* sdp_text, void* userdata) {
    printf("ICE candidate found\n");
}

void on_ice_state_change(PeerConnectionState state, void* userdata) {
    printf("ICE state: %s\n", peer_connection_state_to_string(state));
}

void on_dc_message(char* msg, size_t len, void* userdata, uint16_t sid) {
    printf("DataChannel message: %.*s\n", (int)len, msg);
}

void on_dc_open(void* userdata) {
    printf("DataChannel opened\n");
}

void on_dc_close(void* userdata) {
    printf("DataChannel closed\n");
}

int main()
{
    // Initialize the WebRTC library
    if (peer_init() != 0) {
        printf("WebRTC init failed\n");
        return -1;
    }

    // Configure PeerConnection
    PeerConfiguration config = {0};
    config.ice_servers[0] = (IceServer){ "stun:stun.l.google.com:19302", NULL, NULL };
    config.audio_codec = CODEC_PCMU;
    config.video_codec = CODEC_H264;
    config.datachannel = DATA_CHANNEL_STRING;

    // Create PeerConnection
    PeerConnection* pc = peer_connection_create(&config);
    if (!pc) {
        printf("Create peer connection failed\n");
        peer_deinit();
        return -1;
    }

    // Register callbacks
    peer_connection_onicecandidate(pc, on_ice_candidate);
    peer_connection_oniceconnectionstatechange(pc, on_ice_state_change);
    peer_connection_ondatachannel(pc, on_dc_message, on_dc_open, on_dc_close);

    // Create DataChannel
    peer_connection_create_datachannel(pc, DATA_CHANNEL_RELIABLE, 0, 0, "chat", "");

    // Connect to the signaling server
    peer_signaling_connect("http://192.168.1.100:8080", NULL, pc);

    // Run the event loop in a separate thread
    std::thread loop_thread([&]() {
        while (running) {
            peer_connection_loop(pc);
            peer_signaling_loop();
        }
    });

    // Streaming loop
    while (running) {
        // Get video frame data video_data, video_size, video_timestamp
        peer_connection_send_video(pc, video_data, video_size, video_timestamp_us);

        // Get audio frame data audio_data, audio_size, audio_timestamp
        peer_connection_send_audio(pc, audio_data, audio_size, audio_timestamp_us);
    }

    // Clean up
    running = 0;
    loop_thread.join();
    peer_signaling_disconnect();
    peer_connection_destroy(pc);
    peer_deinit();

    return 0;
}

The above code needs to be compiled into an elf executable file using the build tools in the k230 linux sdk environment, and then copied to the development board for execution.