30.dock-livestream

Overview

The live stream function mainly sends the camera payload of the aircraft and the video stream of the DJI Dock to the tripartite cloud platform for broadcasting, and users can conveniently broadcast live on the remote web page. The live stream function supports the start, stop, resolution setting, and lens switching of the live stream.

Supported Live Streaming Types

Type	Description
Agora	The DJI public cloud platform is also based on the "Interactive Live Streaming Standard" function of Agora. The overall live broadcast delay is relatively low and the effect is good. For the third-party cloud privatization deployment, Agora also provides a hybrid cloud deployment model. The data is in the customer's private server, and then a link is opened through the air gap to Agora's public cloud. This link channel is mainly used to upgrade and operate and maintain the privatized deployed servers.
RTMP	Real-Time Messaging Protocol (RTMP) is a communication protocol for streaming audio, video and data over the Internet. This protocol is based on TCP and is a protocol family that includes the RTMP and RTMPT, RTMPS, RTMPE and many other variants.
GB28181	GB/T 28181-2016 is a transmission control standard for the access of security video equipment to platforms in Mainland China. For some servers which already have 28181 downlink gateway, the data rate of DJI enterprise devices can be pushed to the server directly through this protocol.

Live Streaming Framework of DJI Dock

As shown above, the aircraft flight platform is not directly connected to the tripartite cloud platform, it needs to be forwarded through the remote control or the DJI Dock. The communication between the remote control and the DJI Dock and the aircraft is still using DJI private AirLink.

The tripartite cloud platform requires pre-deployment of MQTT and streaming media server. DJI's streaming protocol supports Agora, RTMP, and GB28181. MQTT is mainly used for message communication, configuration information setting and reading.

Interaction Sequence Diagram

sequenceDiagram
participant client as DJI Dock
participant server as Cloud Server
participant h5 as Web Page

client ->> server: Livestream ability update Topic: thing/product/{device_sn}/state<br/> Device push state topic, and the cloud server parse live broadcast capability structure(live_capacity)


note over client,h5: Web side click to start the live stream

server ->> client: Start livestreaming Topic: thing/product/{gateway_sn}/services<br/>Method: live_start_push
client -->> server: Device response Topic: thing/product/{gateway_sn}/services_reply<br/>Method: live_start_push

client ->> server: Dock push streaming to server
server ->> h5: pull streaming
activate h5

server ->> client: Set livestream quality Topic: thing/product/{gateway_sn}/services<br/>Method: live_set_quality
client -->> server: Device response Topic: thing/product/{gateway_sn}/services_reply<br/>Method: live_set_quality
h5 ->> h5: Live streaming quality adjustment

server ->> client: Set livestream lens Topic: thing/product/{gateway_sn}/services<br/>Method: live_lens_change
client -->> server: Device response Topic: thing/product/{gateway_sn}/services_reply<br/>Method: live_lens_change
h5 ->> h5: lens switch

server ->> client: Stop livestreaming Topic: thing/product/{gateway_sn}/services<br/>Method: live_stop_push
client -->> server: Device response Topic: thing/product/{gateway_sn}/services_reply<br/>Method: live_stop_push

deactivate h5

Detailed API Realization

Live Streaming (MQTT)

• Livestream ability update live_capacity field is in the thing model of the gateway device, which is only pushed when the status of device is changed. The field contains the total amount of streams for live streaming, the total amount of streams for live streaming at the same time, live streaming ability list of devices.

• Start livestreaming The server side sends Start livestreaming instruction, there are protocol type, live stream quality and other information contained in the instruction.

• Stop livestreaming

• Set livestream quality The quality can be set, and the enumeration value of quality can be checked in the "Server API" chapter.

• Set livestream lens The live stream function can change the lens without influencing the live stream progress. The enumeration value of lenses can be checked in the "Server API" chapter.