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Platforms and browsers supported
Chrome | Firefox | Safari 11 | Edge | |
|---|---|---|---|---|
Windows | + | + | + | |
Mac OS | + | + | + | |
Android | + | + | ||
iOS | - | - | + |
Settings
The following WCS settings are intended to limit publishing bitrate:
| On browser side (JavaScript) | On server side (flashphoner.properties) | |
|---|---|---|
| Minimum bitrate limit | constraints.video.minBitrate | webrtc_cc_min_bitrate |
| Maximum bitrate limit | constraints.video.maxBitrate | webrtc_cc_max_bitrate |
On browser side, bitrate limits are set in kilobits per second, for example
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If maxBitrate is set, WCS server will send REMB command to decrease bitrate when this limit is reached.
If minBitrate is set, WCS server will stop sending REMB command to decrease bitrate when this limit is reached.
Therefore, the settings define 3 ranges with its own bitrate management algorithm:
| № | Range | Algorithm |
|---|---|---|
| 1 | [0, minBitrate] | WCS stops bitrate management and not send any REMB commands |
| 2 | [minBitrate, maxBitrate] | WCS server makes active bitrate management: depending on jitter and incoming traffic uniformity WCS decides to send REMB commands to decrease bitrate. If channel is good, WCS does nothing and bitrate is not decreasing |
| 3 | [maxBitrate, ...] | WCS constantly sends bitrate decrease commands until it reduce to maxBitrate |
How to enforce bitrate increasing
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| Code Block | ||
|---|---|---|
| ||
webrtc_sdp_min_bitrate_bps=3000000 webrtc_sdp_max_bitrate_bps=7000000 |
These parameters are ste set in bps. In the exampel example above, the settings have a same effect as
| Code Block | ||
|---|---|---|
| ||
x-google-max-bitrate=7000;x-google-min-bitrate=3000 |
These settings are intended for Chromium-based browsers and work with, e.g., Opera, Vivaldi and Yandex.Browser. Also, they are applied when iOS Safari 12 is used. They do not work with Firefox and Edge.
Usage
Bitrate limiting in certain borders can be useful for example when publishing video to Safari browser subscribers. This browser is sensitive to bitrate jumps, in this case picture quality loses until freeze and browser hangs. It is recommended to stabilize bitrate when publishing streams for Safari viewers by setting narrow limits of bitrate change, for example
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