Thanks, we maybe will start a EXE software to sent out RTMP from PPTX.
Screenshare use a lot of CPU, and once we got screen + webcam, freezes happens.
Yes, browser uses CPU while capturing screen, but another applications (OBS Studio for example) also require a lot of CPU while streaming unless hardware acceleration is enabled.
So this seems as common drawback: presenter should have a powerful desktop with GPU supported by browser/OBS/etc.
About freezes, there can be the following reasons for them:
1) Hardware is not powerful enough to stream (as we discussed above)
2) Publisher channel is not enough to stream screen share (FullHD) and webcam (HD for example) simultaneously. In this case, reducing webcam resolution|bitrate should help. If channel is lossy, switching to TCP transport
for WebRTC should also help (RTMP publishing can also be useful, but it gives more latency comparing to WebRTC).