Hwangsae means stork and acts mainly as the SRT relay to provide the lowest latency to end-user.

There are two modules for handling SRT streaming.

Hwangsae Relay performs the SRT relay. Edge devices send one SRT stream to Relay which then can be consumed by N different SRT sinks. It uses:

• chamge: to register to the message broker and receive messages
• gaeugli: to handle the SRT streaming

Hwangsae Recorder allows the system to record streaming from an Edge device via the Hwangsae Relay. The module can also split the output across multiple files to improve recording handling.

Hwangsae Transmuxer allows to merge several .ts files in a single .mp4 file properly handling gaps between input segments. The module can also split the output across multiple files to improve recording handling.

Command line tool to record SRT streams.

Usage

$ hwangsae-recorder-1.0 uri

uri: Source SRT stream URI

Command line tool to merge several .ts files into a single .mp4 file.

Usage

$ hwangsae-transmuxer-1.0 [options] files

files: List of input files

Options

• -o: Output file name
• -s: Time to use for splitting, can be used multiple times

Role of agents are for communicating with another process. Agents include D-BUS API that is created by code generator from defined XML in the path of chamge/dbus/.

Hwangsae Relay Agent uses the Hwangsae Relay to performs the SRT relay. This allows N different clients to access the streaming generated by the Edge device, including Recorder agent, which improves the scalability of the system.

Hwangsae Recorder Agent uses the Hwangsae Recorder to record SRT streaming in a local filesystem. It also implements a HTTP server to allow easy access to the recorded video.

Each broker/agent has its own settings which are listed below.

Schema: org.hwangsaeul.hwangsae.relay

$ gsettings list-recursively org.hwangsaeul.hwangsae.relay
org.hwangsaeul.hwangsae.relay external-ip ''
org.hwangsaeul.hwangsae.relay sink-port uint32 8888
org.hwangsaeul.hwangsae.relay source-port uint32 9999

• external-ip: Public IP address used to contact the Relay. If set, this value will be used when building the URL instead of the local IP address
• sink-port: UDP port used to receive streaming from Edge devices
• source-port: UDP port used to send streaming to clients

For more details check the file hwangsae/org.hwangsaeul.hwangsae.gschema.xml

Schema: org.hwangsaeul.hwangsae.recorder

$ gsettings list-recursively org.hwangsaeul.hwangsae.recorder
org.hwangsaeul.hwangsae.recorder external-ip ''
org.hwangsaeul.hwangsae.recorder http-port uint32 8092
org.hwangsaeul.hwangsae.recorder recording-dir '/tmp'
org.hwangsaeul.hwangsae.recorder relay-address '127.0.0.1'
org.hwangsaeul.hwangsae.recorder relay-api-port uint32 8080
org.hwangsaeul.hwangsae.recorder relay-stream-port uint32 9999

• external-ip: Public IP address used to contact the Recorder. If set, this value will be used when building the URL instead of the local IP address
• http-port: TCP port used for internal HTTP server
• recording-dir: Local folder for storage recording files. Inside it a folder will be created for each Edge device
• relay-address: IP address of the Relay Agent used to access the streaming
• relay-api-port: TCP port to contact Relay's REST API
• relay-stream-port: UDP port to contact Relay's streaming

For more details check the file hwangsae/org.hwangsaeul.hwangsae.gschema.xml

Each agent implements its own D-BUS API to allow easy interaction with the service.

Start Starts the streaming of a given Edge device allowing to N clients to access it via the returned URL.

Arguments

• edge_id (s): Unique identifier for the Edge device
• width (i): Streaming width
• height (i): Streaming height
• fps (i): Streaming FPS
• bitrates (i): Streaming bitrate

Return

• url (s): URL to use to reach the streaming

Stop Stops the streaming of a given Edge device.

Arguments

• edge_id (s): Unique identifier for the Edge device

For more details check the file hwangsae/dbus/org.hwangsaeul.Hwangsae1.EdgeInterface.xml

Start Starts a new recording, which will trigger the start of the streaming for the given Edge device.

Arguments

• edge_id (s): Unique identifier for the Edge device

Return

• record_id (s): Unique identifier for recording

Stop Stops a recording without stopping the streaming from Edge device.

Arguments

• edge_id (s): Unique identifier for the Edge device

LookupByRecordId Retrieves the list of files of a given recording in a time window.

Arguments

• record_id (s): Unique identifier for recording
• from (x): Timestamp lower limit for filter results
• to (x): Timestamp upper limit for filter results

Return

• edge_id (s): Unique identifier for the Edge device

• file_list: List of files that match the lookup criteria with

  • file_id (s): Unique identifier for the file
  • file_start (x): Timestamp of the recording file start
  • file_end (x): Timestamp of the recording file end
  • size (x): Size of the recording file

LookupByEdgeId Retrieves the list of records/files of a given Edge device in a time window.

Arguments

• edge_id (s): Unique identifier for the Edge device
• from (x): Timestamp lower limit for filter results
• to (x): Timestamp upper limit for filter results

Return

• file_list: List of files that match the lookup criteria with
  • record_id (s): Unique identifier for recording
  • file_id (s): Unique identifier for the file
  • file_start (x): Timestamp of the recording file start
  • file_end (x): Timestamp of the recording file end
  • size (x): Size of the recording file

Url Retrieves the URL to acces a specific recording file.

Arguments

• edge_id: Unique identifier for the Edge device
• file_d: Unique identifier for the file to be downloaded

Return

• url: URL to download the specified file

Delete Deletes a specific recording file.

Arguments

• edge_id: Unique identifier for the Edge device
• file_id: Unique identifier for the file to be downloaded

For more details check the file hwangsae/dbus/org.hwangsaeul.Hwangsae1.RecorderInterface.xml

In the above APIs these ids are used

• edge_id: Unique random number which identifies a Edge device. This id is used by the device during the enroll and activation process.
• record_id: Unique identifier for a recording, current format is start_timestamp
• file_id: Unique identifier for a file in a recording, current format is recording_id-file_start_timestamp-file_stop_timestamp

To build from sources follow the procedure described in

Build from sources

After building from sources Hwangsae Relay Agent can be run with

/usr/local/bin/hwangsae-relay-agent

Also, Hwangsae Recorder Agent can be run with

/usr/local/bin/hwangsae-recorder-agent

Experimental versions of Hwangsae are daily generated in launchpad.

$ sudo add-apt-repository ppa:hwangsaeul/nightly
$ sudo apt-get update
$ sudo apt-get install hwangsae-agent hwangsae-tools libhwangsae-dev libhwangsae1