...

RTP activity can be checked for publishing streams only, not for playing streams.

If Chrome browser sends empty video due to web camera conflict

Some Chrome versions does not return an error if web camera is busy, but publish a stream with empty video (black screen). In this case, stream publishing can be stopped by two ways: using JavaScript and HTML5 on client, or using server settings.

Stopping a stream with empty video on client side

Videotrack that Chrome browsers creates for busy web camera, stops after no more than one second publishing, then stream is send without a videotrack. In this case videotrack state (readyState variable) changes to ended, and corresponding  onended event is generated that can be catched by web application. To use this event:

...

Disable tracks activity checking by stream name

Since build 5.2.1784 it is possible to disable video and audio tracks activity checking for the streams with names matching a regular expression

rtp_activity_audio_exclude=stream1
rtp_activity_video_exclude=stream1

The feature may be useful for streams in which a media traffic can stop for a long time, for example, screen sharing streams from an application window

rtp_activity_audio_exclude=.*-screen$
rtp_activity_video_exclude=.*-screen$

In this case tracks activity checking will not be applied to the tracks named like conference-123-user-456-screen 

If Chrome browser sends empty video due to web camera conflict

Some Chrome versions does not return an error if web camera is busy, but publish a stream with empty video (black screen). In this case, stream publishing can be stopped by two ways: using JavaScript and HTML5 on client, or using server settings.

Stopping a stream with empty video on client side

Videotrack that Chrome browsers creates for busy web camera, stops after no more than one second publishing, then stream is send without a videotrack. In this case videotrack state (readyState variable) changes to ended, and corresponding  onended event is generated that can be catched by web application. To use this event:

1. Add to web application script the registartion function for onended event handler, in which stream pub;ishing is stopped with stream.stop()

...

    session.createStream({
        name: streamName,
        display: localVideo,
        cacheLocalResources: true,
        receiveVideo: false,
        receiveAudio: false,
        videoContentHint: "detail"
        ...
    }).publish();

By default, this In WebSDK builds before 2.0.242 this option is set to detail by default and forces browsers to keep the publishing resolution as set in constraints. However, browser can drop FPS in this case when publishing stream from som USB web cameras. If FPS should be kept mo matter to resolution, the option should be set to to motion

    session.createStream({
        name: streamName,
        display: localVideo,
        cacheLocalResources: true,
        receiveVideo: false,
        receiveAudio: false,
        videoContentHint: "motion"
        ...
    }).publish();

Since WebSDK build 2.0.204242, videoContentHint selection is available in Media   is set to motion by default. The detail or text values should be set only for screen sharing streaming in browser.

Since WebSDK build 2.0.204 videoContentHint selection is available in Media Device example

FPS management in Firefox browser

...

session.createStream({
    name: streamName,
    display: remoteVideo,
    constraints: {session.createStream({
    name: streamName,
    display: remoteVideo,
    constraints: {
        audio: {
            bitrate: 64000
        },
        ...
    }
    ...
}).publish();

or on server side

opus_formats = maxaveragebitrate=64000;stereo=1;sprop-stereo=1;

In this case, Firefox browser publishes stereo audio without additional setup.

Stereo audio publishing in Chrome based browsers

A certain client setup is required to publish stereo audio from Chrome. Thre is two ways to set this up depending on client implementation

Using Web SDK

If Web SDK is used in project, it is necessary to set the fiollowing constraint option:

session.createStream({
    name: streamName,
    display: localVideo,
    constraints: {
        audio: {
            stereo: true
        },
        ...
    }
    ...
}).publish();

Using Websocket API

If only Websocket API is used in project, it is necessary to disable echo cancellation

    var constraints = {
        audio: {
            echoCancellation: false,
            googEchoCancellation: false
        },
        ...
    };
    ...
    navigator.getUserMedia(constraints, function (stream) {
        ...
    }, reject);

If echo cancellation is enabled, Chrome will publish mono audio even if stereo is set in Opus codec options.

How to bypass an encrypted UDP traffic blocking

Sometimes an encrypted UDP mediatraffic may be blocked by ISP. In this case, WebRTC stream publishing over UDP will fail with Failed by RTP activity error. To bypass this, it is recommended to use TCP transport at client side

session.createStream({
    name: streamName,
    display: localVideo,
    transport: "TCP"
    ...
}).publish();

Another option is to use external or internal TURN server or publish a stream via RTMP or RTSP.

Redundancy support while publishing audio

Since build 5.2.1969 a redundancy is supported while publishing audio data (RED, RFC2198). This allows to reduce audio packet loss when using opus codec. The feature may be enabled with the following parameter

codecs=red,opus,alaw,ulaw,g729,speex16,g722,mpeg4-generic,telephone-event,h264,vp8,flv,mpv

Note that red codec should be set before opus codec. In this case a browser supporting RED will send a redundancy data in audio packets. Note that audio publishing bitrate will be raised.

RED should be excluded for the cases when it cannot be applied:

codecs_exclude_sip=red,mpeg4-generic,flv,mpv
codecs_exclude_sip_rtmp=red,opus,g729,g722,mpeg4-generic,vp8,mpv

Getting an additional information about publisher configuration

Since WebSDK 2.0.246 build shipped with WCS build 5.2.2015 and later an additional information about publisher configuration will be sent to server. The data may help to debug and solve a stream publishing issues.

The data are sent in REST hooks.

System and browser information

System and browser information is sent in /connect REST hook

{
  "nodeId" : "VuQnlozpitGdVKzoIZg3f2JmJdMldzPV@192.168.0.40",
  "appKey" : "defaultApp",
  "sessionId" : "/192.168.0.231:11641/192.168.0.40:8443-b7efee23-45ac-4591-9aec-37f896ef10f1",
  ...,
  "clientInfo" : {
    "architecture" : "x86",
    "bitness" : "64",
    "brands" : [ {
      "brand" : "Not/A)Brand",
      "version" : "8"
    }, {
      "brand" : "Chromium",
      "version" : "126"
    }, {
      "brand" : "Google Chrome",
      "version" : "126"
    } ],
    "fullVersionList" : [ {
      "brand" : "Not/A)Brand",
      "version" : "8.0.0.0"
    }, {
      "brand" : "Chromium",
      "version" : "126.0.6478.127"
    }, {
      "brand" : "Google Chrome",
      "version" : "126.0.6478.127"
    } ],
    "mobile" : false,
    "model" : "",
    "platform" : "Windows",
    "platformVersion" : "10.0.0"
  }
}

System and browser information is available at server side in response to /connection/find  and /connection/find_all REST queries.

Publisher media devices information

Publisher media devices information is sent in /publishStream REST hook

{
  "nodeId" : "d2hxbqNPE04vGeZ51NPhDuId6k3hUrBB@192.168.0.39",
  "appKey" : "defaultApp",
  "sessionId" : "/192.168.0.83:42172/192.168.0.39:8443-325c8258-81a6-43de-8c74-1bf582fb436a",
  "mediaSessionId" : "bb237f90-39be-11ef-81b8-bda3bf19742b",
  "name" : "test",
  "published" : true,
  ...,
  "localMediaInfo" : {
    "devices" : {
      "video" : [ {
        "id" : "bc18c5c2510d338d7b2c26bce4e37967feea3172f54ba2077558775d51839419",
        "label" : "HD Webcam C615 (046d:082c)",
        audio"type" : {"camera"
      }, {
     bitrate   "id" : 64000"1f78289ccdbf27d67d605a35d6288acbdefe257275d4b5403525fb5cb1e1822e",
        }"label" : "HP HD Camera (0408:5347)",
        ...
    }
"type" : "camera"
      ...
}).publish();

or on server side

opus_formats = maxaveragebitrate=64000;stereo=1;sprop-stereo=1;

In this case, Firefox browser publishes stereo audio without additional setup.

Stereo audio publishing in Chrome based browsers

A certain client setup is required to publish stereo audio from Chrome. Thre is two ways to set this up depending on client implementation

Using Web SDK

If Web SDK is used in project, it is necessary to set the fiollowing constraint option:

session.createStream({
    name: streamName,
    display: localVideo,
    constraints: { ],
      "audio" : [ {
        "id" : "de988681c02901db0bfe012cd393eb2db5245fc2fb34709a26686ae6ca85b3ba",
        "label" : "HD Webcam C615 Mono",
        "type" : "mic"
      }, {
        "id" : "default",
        audio"label" : {"Default",
            stereo"type" : true"mic"
        }, {
        ..."id" : "e7f4beddb0d71ea1f618cf3bab0f7e94053b622ddaf312c403824caa006f5889",
    }
    ...
}).publish();

Using Websocket API

If only Websocket API is used in project, it is necessary to disable echo cancellation

    "label" : "Quantum 600 Mono",
     var constraints = {
"type" : "mic"
      audio:}, {
             "id"  echoCancellation: false"fc6ac664dec546102d3f83b7fb5981afe3f0e88f8b76ffbe660ecfdd989bcf96",
        "label" : "Family  googEchoCancellation: false
17h (Models 10h-1fh) HD Audio Controller Analog Stereo",
         },"type" : "mic"
      }  ...]
    };,
    "tracks" : ...{
      navigator.getUserMedia(constraints, function (stream)"video" : [ {
        ...
    }, reject);

If echo cancellation is enabled, Chrome will publish mono audio even if stereo is set in Opus codec options.

How to bypass an encrypted UDP traffic blocking

Sometimes an encrypted UDP mediatraffic may be blocked by ISP. In this case, WebRTC stream publishing over UDP will fail with Failed by RTP activity error. To bypass this, it is recommended to use TCP transport at client side

session.createStream("trackId" : "1922f1d0-3a3f-4fa5-bd6e-e91ac84c666c",
        "device" : "HD Webcam C615 (046d:082c)"
      } ],
      "audio" : [ {
    name: streamName    "trackId" : "44187ea1-b756-4feb-80f0-ac57934c2200",
    display: localVideo,
   "device" transport: "TCP"
    ...
}).publish();

...

MediaStreamAudioDestinationNode"
      } ]
    }
  }
}

Where:

• devices - a media devices list available to the browser
• tracks - what devices audio and video tracks of the stream published are capturing from

Publisher media devices information is available at server side in response to /stream/find  and /stream/find_all REST queries.

Known issues

1. If the web app is inside an iframe element, publishing of the video stream may fail.

...