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docs: add notes on how to tweak screen sharing quality

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prlanzarin 2023-10-02 14:51:52 -03:00
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docs/docs/administration/customize.md
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@ -493,6 +493,49 @@ yq w -i $HTML5_CONFIG 'public.kurento.cameraProfiles.(id==hd).default' false
chown meteor:meteor $HTML5_CONFIG
```
#### Change screen sharing quality parameters
Screen sharing quality can be tweaked to either improve quality or reduce bandwidth usage.
There are different configurations for live meetings and recordings and they need to be changed independently from each other.
For **recordings**, the following parameters can be changed (presentation format):
- `/usr/local/bigbluebutton/core/scripts/presentation.yml`: `deskshare_output_width` (default: 1280)
- `/usr/local/bigbluebutton/core/scripts/presentation.yml`: `deskshare_output_height` (default: 720)
- `/usr/local/bigbluebutton/core/scripts/presentation.yml`: `deskshare_output_framerate` (default: 5)
As an example, suppose you want to increase the output resolution and framerate of the recorded screen share media to match a 1080p/15 FPS stream. The following changes would be necessary:
- `$ yq w -i /usr/local/bigbluebutton/core/scripts/presentation.yml deskshare_output_width 1920`
- `$ yq w -i /usr/local/bigbluebutton/core/scripts/presentation.yml deskshare_output_height 1080`
- `$ yq w -i /usr/local/bigbluebutton/core/scripts/presentation.yml deskshare_output_framerate 15`
For **live meetings**, the following parameters can be changed:
- `/etc/bigbluebutton/bbb-html5.yml`: `public.kurento.screenshare.bitrate`
- `/etc/bigbluebutton/bbb-html5.yml`: `public.kurento.screenshare.constraints`
The bitrate is specified in kbps and represents screen sharing's maximum bandwidth usage. Setting it to a higher value *may* improve quality but also increase bandwidth usage, while setting it to a lower value *may* reduce quality but will reduce average bandwidth usage.
The constraints are specified as an YAML object with the same semantics as the [MediaTrackConstraints](https://developer.mozilla.org/en-US/docs/Web/API/MediaTrackConstraints) from the WebRTC specification. We recommend checking the aforementioned MDN link as well as the [Media Capture and Streams API spec](https://www.w3.org/TR/mediacapture-streams) for an extensive list of constraints.
To set new screen sharing constraints, translate the JSON constraints object into an YAML format object and put it into `public.kurento.screenshare.constraints`. Restart bbb-html5 afterwards.
As an example, suppose you want to set the maximum screen sharing resolution to 1080p, alter the maxium bitrate to 2000 kbps and set a 10 FPS target. The following would need to be added to `etc/bigbluebutton/bbb-html5.yml`:
```yaml
public:
kurento:
screenshare:
bitrate: 2000
constraints:
audio: true
video:
width:
max: 1920
height:
max: 1080
frameRate:
ideal: 10
max: 10
```
#### Run three parallel Kurento media servers
[ Available since BigBluebutton 2.2.24+ ]