Overview

Since WCS build 5.2.1193 it is possible to publish MPEG-TS RTP stream via UDP to WCS. The feature can be used to publish H264+AAC stream from software or hardware encoder supporting MPEG-TS.

Codecs supported

• H264
• AAC

Operation flowchart

1. Publisher sends REST API query /mpegts/startup 

2. Publisher receives 200 OK with URI to publish

3. Stream is publishing to WCS using URI

4. Browser establishes Websocket connestion and sends play  command.

5. Browser receives WebRTC stream and plays it on web page.

Testing

1. For test we use:

• WCS server
• ffmpeg to publish MPEG-TS stream
• Player web application in Chrome browser to play the stream

2. Send /mpegts/startup query with stream name test 

curl -H "Content-Type: application/json" -X POST http://test1.flashphoner.com:8081/rest-api/mpegts/startup -d '{"localStreamName":"test"}'

Where test1.flashphoner.com - WCS server address

3. Receive 200 OK response

{
  "localMediaSessionId": "32ec1a8e-7df4-4484-9a95-e7eddc45c508",
  "localStreamName": "test",
  "uri": "udp://test1.flashphoner.com:31006",
  "status": "CONNECTED",
  "hasAudio": true,
  "hasVideo": true,
  "record": false,
  "timeout": 90000,
  "maxTimestampDiff": 90000
}

4. Publish MPEG-TS stream using URI from the response

 ffmpeg -re -i bunny360p.mp4 -c:v libx264 -c:a aac -b:a 160k -bsf:v h264_mp4toannexb -keyint_min 60 -profile:v baseline -preset veryfast -f mpegts "udp://test1.flashphoner.com:31006?pkt_size=1316"

5. Open Player web application. Set the stream name test to "Stream name" field and click "Start" button. Stream playback will start

Configuration

Stop stream publishing if there are no media data

By default, MPEG-TS stream publishing will stop at server side if server doe not receive any media data from publisher in 90 seconds. The timeout is set in milliseconds by the following papameter

mpegts_stream_timeout=90000

Close subscribers sessions if publisher stops sending media data

If publisher stopped sending media data by some reason, then started again (for example, ffmpeg was restarted), the stream frame timestamps sequence is corrupting. Te stream cannot be played via WebRTC correctky in this case. As workaround, all the subscribers sessions will be closed if stream timestamps sequence corruption occurs, then all the si=ubscribers should connect to the stream again. A maximum timestamp difference is set in seconds by the following parameter

mpegts_max_pts_diff=1

REST API

A REST-query should be HTTP/HTTPS POST request as follows:

• HTTP: http://test.flashphoner.com:8081/rest-api/mpegts/startup
• HTTPS: https://test.flashphoner.com:8444/rest-api/mpegts/startup

Where:

• test.flashphoner.com - is the address of the WCS server
• 8081 - is the standard REST / HTTP port of the WCS server
• 8444 - is the standard HTTPS port
• rest-api - is the required part of the URL
• /mpegts/startup - REST mathod to use

REST methods and response states

{
  "localStreamName":"test"
}

{
  "localMediaSessionId": "32ec1a8e-7df4-4484-9a95-e7eddc45c508",
  "localStreamName": "test",
  "uri": "udp://192.168.1.39:31006",
  "status": "CONNECTED",
  "hasAudio": true,
  "hasVideo": true,
  "record": false,
  "timeout": 90000,
  "maxTimestampDiff": 90000
}

{
  "localStreamName":"test",
  "uri": "udp://192.168.1.39:31006"
}

[
 {
  "localMediaSessionId": "32ec1a8e-7df4-4484-9a95-e7eddc45c508",
  "localStreamName": "test",
  "uri": "udp://192.168.1.39:31006",
  "status": "CONNECTED",
  "hasAudio": true,
  "hasVideo": true,
  "record": false,
  "timeout": 90000,
  "maxTimestampDiff": 90000
 }
]

[
 {
  "localMediaSessionId": "32ec1a8e-7df4-4484-9a95-e7eddc45c508",
  "localStreamName": "test",
  "uri": "udp://192.168.1.39:31006",
  "status": "CONNECTED",
  "hasAudio": true,
  "hasVideo": true,
  "record": false,
  "timeout": 90000,
  "maxTimestampDiff": 90000
 }
]

{
  "localStreamName":"test"
}

Parameters

Known issues

1. When MPEG-TS stream publishing via UDP is stopped at server side via REST API query /mpegts/terminate , publishing encoder still sends media data

Symptoms: ffmpeg still sends data via UDP when MPEG-TS stream publishing is stopped on server

Solution: this is normal behaviour for UDP because the protocol itself provides no any methods to let publisher know the UDP port is already closed