Web Call Server 5.1 - EN
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Code Block
languagejs
themeRDark
    session.createStream({
        name: streamName,
        display: localVideo,
        constraints: {video: true, audio: false}
        ...
    }).publish();

Disable resolution constraints normalization in Safari browser

By default, WebSDK normalizes stream publishing resolution constraints set in Safari browser. In this case, if width or height is not set, or equal to 0, then the picture resolution is forced to 320x240 or 640x480. Since WebSDK build 0.5.28.2753.109 (hash 149855cc050bf7512817104fd0104e9cce760ac4), it is possible to disable normalization and pass resolution constarints to the browser as is. for example:

...

languagejs
themeRDark

...

Audio only stream publishing

In most cases, it is enough to set the constraints to publish audio only stream:

Code Block
languagejs
themeRDark
    session.createStream({
        name: streamName,
        display: localVideo,
            width: {ideal: 1024},
            height: {ideal: 768constraints: {video: false, audio: true}
        },
        audio: true
    }
}).on(STREAM_STATUS.PUBLISHING, function (publishStream) {...
    ...
});
publishStream.publish();

Known issues

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

Symptoms: IceServer errors in the browser console.

Solution: put the app out of iframe to an individual page.

2. If publishing of the stream goes under Windows 10 or Windows 8 and hardware acceleration is enabled in the Google Chrome browser, bitrate problems are possible.

Symptoms: low quality of the video, muddy picture, bitrate shown in chrome://webrtc-internals is less than 100 kbps.

Solution: turn off hardware acceleration in the browser, switch the browser of the server to use the VP8 codec.

3. Stream publishing with local video playback in Delight Player does not work in MS Edge

Symptoms: when stream is published in MS Edge, local video playback does not start in Delight Player

Solution: use another browser to publish a stream

4. In some cases microphone does not work in Chrome browser while publishing WebRTC stream.

Symptoms: michrophone does not work while publishing WebRTC stream, including example web applications out of the box

Solution: turn off gain node creation in Chrome browser using WebSDK initialization parameter createMicGainNode: false

...

languagejs
themeRDark

...

Audio only stream publishing in Safari browser

When audio only stream is published from iOS Safari browser with constraints, browser does not send audio packets. To workaround this, a stream should be published with video, then video should be muted:

Code Block
languagejs
themeRDark
    session.createStream({
        name: streamName,
        display: localVideo,
        constraints: {video: true, audio: true}
        ...
    flashMediaProviderSwfLocation: '../../../../media-provider.swf',}).on(STREAM_STATUS.PUBLISHING, function (stream) {
        stream.muteVideo();
    createMicGainNode: false
    ...
    }).publish();

Note that microphone gain setting will not work in this case.

5. G722 codec does not work in Edge browser

Symptoms: WebRTC stream with G722 audio does not publish in Edge browser

Solution: use another codec or another browser. If Edge browser must be used, exclude G722 with the following parameter

Code Block
themeRDark
codecs_exclude_streaming=g722,telephone-event

6. Some Chromium based browsers, for example Opera, Yandex, do not support H264 codec depending on browser and OS version

Symptoms: stream publishing does not work, stream playback works partly (audio only) or does not work at all

Solution: enable VP8 on server side

Code Block
themeRDark
codecs=opus,...,h264,vp8,...

exclude H264 for publishing or playing on clent side

...

languagejs
themeRDark

...

In this case, iOS Safari browser will send emply video packets (blank screen) and audio packets.

Disable resolution constraints normalization in Safari browser

By default, WebSDK normalizes stream publishing resolution constraints set in Safari browser. In this case, if width or height is not set, or equal to 0, then the picture resolution is forced to 320x240 or 640x480. Since WebSDK build 0.5.28.2753.109 (hash 149855cc050bf7512817104fd0104e9cce760ac4), it is possible to disable normalization and pass resolution constarints to the browser as is. for example:

Code Block
languagejs
themeRDark
publishStream = session.createStream({
    ...
    disableConstraintsNormalization: true,
    constraints {
        video: {
            width: {ideal: 1024},
            height: {ideal: 768}
        },
        audio: true
    }
}).on(STREAM_STATUS.PUBLISHING, function (publishStream) {
    ...
});
publishStream.publish();

Note that stream transcoding on server is enabled when stream published as H264 is played as VP8 and vice versa.

7. iOS Safari 12.1 does not send video frames when picture with certain resolution is published

Symptoms: when H264 stream is published from iOS Safari 12.1, subscriber receives audio packets only, publishers WebRTC statistics also shows audio frames only

Solution: enable VP8 on server side

Code Block
themeRDark
codecs=opus,...,h264,vp8,...

exclude H264 for publishing or playing on clent side

Code Block
languagejs
themeRDark
publishStream = session.createStream({
    ...
    stripCodecs: "h264,H264"
}).on(STREAM_STATUS.PUBLISHING, function (publishStream) {
    ...
});
publishStream.publish();

Note that stream transcoding on server is enabled when stream published as H264 is played as VP8 and vice versa.

8. Stream from built-in camera cannot be published in iOS Safari 12 and MacOS Safari 12 in some resolutions

Symptoms: stream publishing from browser fails with error in console

Code Block
themeRDark
Overconstrained error: width

Solution:

a) use only resolutions which passes WebRTC Camera Resolution test

b) use external camera supporting resolutions as needed in MacOS Safari

...

Known issues

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

Symptoms: IceServer errors in the browser console.

Solution: put the app out of iframe to an individual page.

2. If publishing of the stream goes under Windows 10 or Windows 8 and hardware acceleration is enabled in the Google Chrome browser, bitrate problems are possible.

Symptoms: low quality of the video, muddy picture, bitrate shown in chrome://webrtc-internals is less than 100 kbps.

Solution: turn off hardware acceleration in the browser, switch the browser of the server to use the VP8 codec.

3. Stream publishing with local video playback in Delight Player does not work in MS Edge

Symptoms: when stream is published in MS Edge, local video playback does not start in Delight Player

Solution: use another browser to publish a stream

4. In some cases microphone does not work in Chrome browser while publishing WebRTC stream.

Symptoms: michrophone does not work while publishing WebRTC stream, including example web applications out of the box

Solution: turn off gain node creation in Chrome browser using WebSDK initialization parameter createMicGainNode: false

Code Block
languagejs
themeRDark
        Flashphoner.init({
            flashMediaProviderSwfLocation: '../../../../media-provider.swf',
            createMicGainNode: false
        });

Note that microphone gain setting will not work in this case.

5. G722 codec does not work in Edge browser

Symptoms: WebRTC stream with G722 audio does not publish in Edge browser

Solution: use another codec or another browser. If Edge browser must be used, exclude G722 with the following parameter

Code Block
themeRDark
codecs_exclude_streaming=g722,telephone-event

6. Some Chromium based browsers, for example Opera, Yandex, do not support H264 codec depending on browser and OS version

Symptoms: stream publishing does not work, stream playback works partly (audio only) or does not work at all

Solution: enable VP8 on server side

Code Block
themeRDark
codecs=opus,...,h264,vp8,...

exclude H264 for publishing or playing on client side

Code Block
languagejs
themeRDark
publishStream = session.createStream({
    ...
    stripCodecs: "h264,H264"
}).on(STREAM_STATUS.PUBLISHING, function (publishStream) {
    ...
});
publishStream.publish();

Note that stream transcoding on server is enabled when stream published as H264 is played as VP8 and vice versa.

7. iOS Safari 12.1 does not send video frames when picture with certain resolution is published

Symptoms: when H264 stream is published from iOS Safari 12.1, subscriber receives audio packets only, publishers WebRTC statistics also shows audio frames only

Solution: enable VP8 on server side

Code Block
themeRDark
codecs=opus,...,h264,vp8,...

exclude H264 for publishing or playing on clent side

Code Block
languagejs
themeRDark
publishStream = session.createStream({
    ...
    stripCodecs: "h264,H264"
}).on(STREAM_STATUS.PUBLISHING, function (publishStream) {
    ...
});
publishStream.publish();

Note that stream transcoding on server is enabled when stream published as H264 is played as VP8 and vice versa.

8. Stream from built-in camera cannot be published in iOS Safari 12 and MacOS Safari 12 in some resolutions

Symptoms: stream publishing from browser fails with error in console

Code Block
themeRDark
Overconstrained error: width

Solution:

a) use only resolutions which passes WebRTC Camera Resolution test

b) use external camera supporting resolutions as needed in MacOS Safari

c) disable resolution constraints normalization and set width and height as ideal, see example above.

9. Non-latin characters in stream name should be encoded

Symptoms: non-latin characters in stream name are replaced to questionmarks on server side

Solution: use JavaScript function encodeURIComponent() while publishing stream

Code Block
languagejs
themeRDark
    var streamName = encodeURIComponent($('#publishStream').val());    
    session.createStream({
        name: streamName,
        display: localVideo,
        cacheLocalResources: true,
        receiveVideo: false,
        receiveAudio: false
    ...
    }).publish();

10. In some cases, server can not parse H264 stream encoded with CABAC

Symptoms: WebRTC H264 stream publishing does not work

Solution:

a) use lower encoding profile

b) enable VP8 on server side

Code Block
themeRDark
codecs=opus,...,h264,vp8,...

exclude H264 for publishing or playing on clent side

Code Block
languagejs
themeRDark
publishStream = session.createStream({
    ...
    stripCodecs: "h264,H264"
}).on(STREAM_STATUS.PUBLISHING, function (publishStream) {
    ...
});
publishStream.publish();

Note that stream transcoding on server is enabled when stream published as H264 is played as VP8 and vice versa.

11. When playing WebRTC broadcast in Firefox on macOS Catalina, displayed system warning and block on playing H264 stream.

Symptoms: when playing WebRTC broadcast in Firefox on macOS Catalina, displayed system warning "libgmpopenh264.dylib" can`t be opened because it is from an identified developer" and block of playing H264 stream.

Solution: Firefox uses a third-party library unsigned by the developer to work with H264. In accordance with macOS Catalina security policies, this is prohibited. To add an exception, go to System Preferences > Security & Privacy > General > Allow apps downloaded from > App Store and identified developers> "libgmpopenh264.dylib" was blocked from opening because it is not from an identified developer" > tap Open Anyway.