How does the Android platform GB28181 device access terminal realize multi-video channel access?

technical background

When we design the Android platform GB28181 device access module, there is such a scenario requirement, a device may need multiple channels, common scenarios, such as vehicle terminals, a device may need to access multiple cameras, then this The vehicle-mounted terminal device can be used as the main device, and then, under the main device, multiple channels are configured. Does it sound a bit similar to DVR or NVR?

Technical realization

Here, let's talk about how we designed this piece at the time. First, add the device channel when InitGB28181Agent. The specific code is as follows:

    private boolean initGB28181Agent() {
        if ( gb28181_agent_ != null )
            return  true;

        getLocation(context_);

        String local_ip_addr = IPAddrUtils.getIpAddress(context_);
        Log.i(TAG, "[daniusdk.com]initGB28181Agent local ip addr: " + local_ip_addr);

        if ( local_ip_addr == null || local_ip_addr.isEmpty() ) {
            Log.e(TAG, "[daniusdk.com]initGB28181Agent local ip is empty");
            return  false;
        }

        gb28181_agent_ = GBSIPAgentFactory.getInstance().create();
        if ( gb28181_agent_ == null ) {
            Log.e(TAG, "[daniusdk.com]initGB28181Agent create agent failed");
            return false;
        }

        gb28181_agent_.addListener(this);
        gb28181_agent_.addPlayListener(this);
        gb28181_agent_.addAudioBroadcastListener(this);
        gb28181_agent_.addDeviceControlListener(this);
        gb28181_agent_.addQueryCommandListener(this);

        // 必填信息
        gb28181_agent_.setLocalAddress(local_ip_addr);
        gb28181_agent_.setServerParameter(gb28181_sip_server_addr_, gb28181_sip_server_port_, gb28181_sip_server_id_, gb28181_sip_domain_);
        gb28181_agent_.setUserInfo(gb28181_sip_username_, gb28181_sip_password_);
        //gb28181_agent_.setUserInfo(gb28181_sip_username_, gb28181_sip_username_, gb28181_sip_password_);

        // 可选参数
        gb28181_agent_.setUserAgent(gb28181_sip_user_agent_filed_);
        gb28181_agent_.setTransportProtocol(gb28181_sip_trans_protocol_==0?"UDP":"TCP");

        // GB28181配置
        gb28181_agent_.config(gb28181_reg_expired_, gb28181_heartbeat_interval_, gb28181_heartbeat_count_);

        com.gb.ntsignalling.Device gb_device = new com.gb.ntsignalling.Device("34020000001380000001", "安卓测试设备", Build.MANUFACTURER, Build.MODEL,
                    "宇宙","火星1","火星", true);

        if (mLongitude != null && mLatitude != null) {
            com.gb.ntsignalling.DevicePosition device_pos = new com.gb.ntsignalling.DevicePosition();

            device_pos.setTime(mLocationTime);
            device_pos.setLongitude(mLongitude);
            device_pos.setLatitude(mLatitude);
            gb_device.setPosition(device_pos);

            gb_device.setSupportMobilePosition(true); // 设置支持移动位置上报
        }

        gb28181_agent_.addDevice(gb_device);

        com.gb28181.ntsignalling.Device gb_device1 = new com.gb28181.ntsignalling.Device("34020000001380000002", "安卓测试设备2", Build.MANUFACTURER, Build.MODEL,
                "宇宙","火星1","火星", true);

        if (mLongitude != null && mLatitude != null) {
            com.gb28181.ntsignalling.DevicePosition device_pos = new com.gb28181.ntsignalling.DevicePosition();

            device_pos.setTime(mLocationTime);
            device_pos.setLongitude(mLongitude);
            device_pos.setLatitude(mLatitude);
            gb_device1.setPosition(device_pos);

            gb_device1.setSupportMobilePosition(true);
        }

        gb28181_agent_.addDevice(gb_device1);

        if (!gb28181_agent_.createSipStack()) {
            gb28181_agent_ = null;
            Log.e(TAG, "[daniusdk.com]initGB28181Agent gb28181_agent_.createSipStack failed.");
            return  false;
        }

        boolean is_bind_local_port_ok = false;

        // 最多尝试5000个端口
        int try_end_port = gb28181_sip_local_port_base_ + 5000;
        try_end_port = try_end_port > 65536 ?65536: try_end_port;

        for (int i = gb28181_sip_local_port_base_; i < try_end_port; ++i) {
            if (gb28181_agent_.bindLocalPort(i)) {
                is_bind_local_port_ok = true;
                break;
            }
        }

        if (!is_bind_local_port_ok) {
            gb28181_agent_.releaseSipStack();
            gb28181_agent_ = null;
            Log.e(TAG, "[daniusdk.com]initGB28181Agent gb28181_agent_.bindLocalPort failed.");
            return  false;
        }

        if (!gb28181_agent_.initialize()) {
            gb28181_agent_.unBindLocalPort();
            gb28181_agent_.releaseSipStack();
            gb28181_agent_ = null;
            Log.e(TAG, "[daniusdk.com]initGB28181Agent gb28181_agent_.initialize failed.");
            return  false;
        }

        return true;
    }

As you can see, we call addDevice(gb_device); two channels are added, as follows:

com.gb.ntsignalling.Device gb_device = new com.gb.ntsignalling.Device("34020000001380000001", "安卓测试设备", Build.MANUFACTURER, Build.MODEL,
                                                                      "宇宙","火星1","火星", true);

if (mLongitude != null && mLatitude != null) {
    com.gb.ntsignalling.DevicePosition device_pos = new com.gb.ntsignalling.DevicePosition();

    device_pos.setTime(mLocationTime);
    device_pos.setLongitude(mLongitude);
    device_pos.setLatitude(mLatitude);
    gb_device.setPosition(device_pos);

    gb_device.setSupportMobilePosition(true); // 设置支持移动位置上报
}

gb28181_agent_.addDevice(gb_device);

com.gb28181.ntsignalling.Device gb_device1 = new com.gb28181.ntsignalling.Device("34020000001380000002", "安卓测试设备2", Build.MANUFACTURER, Build.MODEL,
                                                                                 "宇宙","火星1","火星", true);

if (mLongitude != null && mLatitude != null) {
    com.gb28181.ntsignalling.DevicePosition device_pos = new com.gb28181.ntsignalling.DevicePosition();

    device_pos.setTime(mLocationTime);
    device_pos.setLongitude(mLongitude);
    device_pos.setLatitude(mLatitude);
    gb_device1.setPosition(device_pos);

    gb_device1.setSupportMobilePosition(true);
}

gb28181_agent_.addDevice(gb_device1);

One device corresponds to two devices.

When the invite request comes, we will return the deviceid, and the upper layer can perform preview processing for different deviceids:

    @Override
    public void ntsOnInvitePlay(String deviceId, SessionDescription session_des) {
        handler_.postDelayed(new Runnable() {
            @Override
            public void run() {
                // 先振铃响应下
                gb28181_agent_.respondPlayInvite(180, device_id_);

                MediaSessionDescription video_des = null;
                SDPRtpMapAttribute ps_rtpmap_attr = null;

                // 28181 视频使用PS打包
                Vector<MediaSessionDescription> video_des_list = session_des_.getVideoPSDescriptions();
                if (video_des_list != null && !video_des_list.isEmpty()) {
                    for(MediaSessionDescription m : video_des_list) {
                        if (m != null && m.isValidAddressType() && m.isHasAddress() ) {
                            video_des = m;
                            ps_rtpmap_attr = video_des.getPSRtpMapAttribute();
                            break;
                        }
                    }
                }

                if (null == video_des) {
                    gb28181_agent_.respondPlayInvite(488, device_id_);
                    Log.i(TAG, "ntsOnInvitePlay get video description is null, response 488, device_id:" + device_id_);
                    return;
                }

                if (null == ps_rtpmap_attr) {
                    gb28181_agent_.respondPlayInvite(488, device_id_);
                    Log.i(TAG, "ntsOnInvitePlay get ps rtp map attribute is null, response 488, device_id:" + device_id_);
                    return;
                }

                Log.i(TAG,"ntsOnInvitePlay, device_id:" +device_id_+", is_tcp:" + video_des.isRTPOverTCP()
                        + " rtp_port:" + video_des.getPort() + " ss rc:" + video_des.getSS-RC()
                        + " address_type:" + video_des.getAddressType() + " address:" + video_des.getAddress());

                long rtp_sender_handle = libPublisher.CreateRTPSender(0);
                if ( rtp_sender_handle == 0 ) {
                    gb28181_agent_.respondPlayInvite(488, device_id_);
                    Log.i(TAG, "ntsOnInvitePlay CreateRTPSender failed, response 488, device_id:" + device_id_);
                    return;
                }

                gb28181_rtp_payload_type_  = ps_rtpmap_attr.getPayloadType();
                gb28181_rtp_encoding_name_ =  ps_rtpmap_attr.getEncodingName();

                libPublisher.SetRTPSenderTransportProtocol(rtp_sender_handle, video_des.isRTPOverUDP()?0:1);
                libPublisher.SetRTPSenderIPAddressType(rtp_sender_handle, video_des.isIPv4()?0:1);
                libPublisher.SetRTPSenderLocalPort(rtp_sender_handle, 0);
                libPublisher.SetRTPSenderSS-RC(rtp_sender_handle, video_des.getSS-RC());
                libPublisher.SetRTPSenderSocketSendBuffer(rtp_sender_handle, 2*1024*1024); // 设置到2M
                libPublisher.SetRTPSenderClockRate(rtp_sender_handle, ps_rtpmap_attr.getClockRate());
                libPublisher.SetRTPSenderDestination(rtp_sender_handle, video_des.getAddress(), video_des.getPort());

                if ( libPublisher.InitRTPSender(rtp_sender_handle) != 0 ) {
                    gb28181_agent_.respondPlayInvite(488, device_id_);
                    libPublisher.DestoryRTPSender(rtp_sender_handle);
                    return;
                }

                int local_port = libPublisher.GetRTPSenderLocalPort(rtp_sender_handle);
                if (local_port == 0) {
                    gb28181_agent_.respondPlayInvite(488, device_id_);
                    libPublisher.DestoryRTPSender(rtp_sender_handle);
                    return;
                }

                Log.i(TAG,"get local_port:" + local_port);

                String local_ip_addr = IPAddrUtils.getIpAddress(context_);

                MediaSessionDescription local_video_des = new MediaSessionDescription(video_des.getType());

                local_video_des.addFormat(String.valueOf(ps_rtpmap_attr.getPayloadType()));
                local_video_des.addRtpMapAttribute(ps_rtpmap_attr);

                local_video_des.setAddressType(video_des.getAddressType());
                local_video_des.setAddress(local_ip_addr);
                local_video_des.setPort(local_port);

                local_video_des.setTransportProtocol(video_des.getTransportProtocol());
                local_video_des.setSS-RC(video_des.getSS-RC());

                if (!gb28181_agent_.respondPlayInviteOK(device_id_,local_video_des) ) {
                    libPublisher.DestoryRTPSender(rtp_sender_handle);
                    Log.e(TAG, "ntsOnInvitePlay call respondPlayInviteOK failed.");
                    return;
                }

                gb28181_rtp_sender_handle_ = rtp_sender_handle;
            }

            private String device_id_;
            private SessionDescription session_des_;

            public Runnable set(String device_id, SessionDescription session_des) {
                this.device_id_ = device_id;
                this.session_des_ = session_des;
                return this;
            }
        }.set(deviceId, session_des),0);
    }

After receiving the ACK, it also carries the deviceid as a distinction:

    @Override
    public void ntsOnAckPlay(String deviceId) {
        handler_.postDelayed(new Runnable() {
            @Override
            public void run() {
                Log.i(TAG,"ntsOnACKPlay, device_id:" +device_id_);

                if (!isRTSPPublisherRunning && !isPushingRtmp && !isRecording) {
                    InitAndSetConfig();
                }

                libPublisher.SetGB28181RTPSender(publisherHandle, gb28181_rtp_sender_handle_, gb28181_rtp_payload_type_, gb28181_rtp_encoding_name_);

                //libPublisher.SetGBTCPConnectTimeout(publisherHandle, 10*60*1000);
                //libPublisher.SetGBInitialTCPReconnectInterval(publisherHandle, 1000);
                //libPublisher.SetGBInitialTCPMaxReconnectAttempts(publisherHandle, 3);

                int startRet = libPublisher.StartGB28181MediaStream(publisherHandle);
                if (startRet != 0) {

                    if (!isRTSPPublisherRunning && !isPushingRtmp  && !isRecording) {
                        if (publisherHandle != 0) {
                            long handle = publisherHandle;
                            publisherHandle = 0;
                            libPublisher.SmartPublisherClose(handle);
                        }
                    }

                    destoryRTPSender();

                    Log.e(TAG, "Failed to start GB28181 service..");
                    return;
                }

                if (!isRTSPPublisherRunning && !isPushingRtmp && !isRecording) {
                    CheckInitAudioRecorder();
                }

                startLayerPostThread();
                isGB28181StreamRunning = true;
            }

            private String device_id_;

            public Runnable set(String device_id) {
                this.device_id_ = device_id;
                return this;
            }

        }.set(deviceId),0);
    }

TerminatePlayer is handled as follows:

    @Override
    public void ntsOnTerminatePlay(String deviceId) {
        handler_.postDelayed(new Runnable() {
            @Override
            public void run() {
                Log.i(TAG, "ntsOnTerminatePlay, stop GB28181 media stream, deviceId=" + device_id_);

                stopGB28181Stream();
                destoryRTPSender();
            }

            private String device_id_;

            public Runnable set(String device_id) {
                this.device_id_ = device_id;
                return this;
            }

        }.set(deviceId),0);
    }

In this way, each deviceid corresponds to an instance. If there are multiple cameras, the cameras can be distinguished according to the deviceid. If the national standard platform side requests which deviceid, it will start the camera collection, encoding and data packaging and uploading corresponding to the deviceid.