spreed/docs/call-experience.md

Call experience

There are multiple factors which can have a smaller and bigger impact on the experience of a call.

Automatic selection of sent video quality

Since version 8.0.8 Nextcloud Talk will automatically select the sent video quality depending on the number of participants sending video and/or audio streams. Both counters are checked and then the lowest matching quality is selected.

If a participant enabled their microphone and starts speaking the video quality is set to "High" for the duration of them talking plus an additional grace period of 5 seconds.

Number of video streams

Streams	Quality
< 4	High
4-7	Medium
8-10	Low
11-14	Very low

14 | Thumbnail

Number of audio streams

Streams	Quality
< 10	High
10-19	Medium
20-29	Low
30-39	Very low

40 | Thumbnail

Video qualities

Quality	Max width	Ideal width	Max height	Ideal height	Max frames	Ideal frames
High	-	720	-	540	-	30
Medium	640	560	480	420	24	24
Low	480	360	320	270	15	15
Very low	320	-	240	-	8	-
Thumbnail	320	-	240	-	1	-

Judging the connection quality

Similar since version 9.0.2 Nextcloud Talk is having an eye on the lost packages and the "round trip time" of the stream data. When the connection is too bad or no data could be transmitted at all, the participant will be informed to try to disable their own video and screenshare. If those two are already off, the participant will see a message that their connection bandwidth or device cannot withhold the necessary load for participating in a call.

The critical values are:

Lost packages: 30% in the last 5 seconds

Too few packages: Less than 10 packages per second

Round trip time: above 1.5 seconds