perf: send encoded h264 packet to webrtc about raspberrypi_webrtc HOT 1 CLOSED

obviously, directly capturing the h264 format from cameras in v4l2 is not a good idea in the webrtc framework.

1. If captured h264 in AdaptedVideoTrackSource and then sent frames to VideoEncoder, webrtc drops frames sometimes, it will make the NAL unit not continuous. So the decoding order is wrong making the broken real-time video on the client side.
2. If captured h264 in VideoEncoder. Although it will not interrupt the sequence, it would not be triggered when webrtc drops frames. We can not drop the delayed buffer because of keeping it in sequence, therefore, the delay will increase over time.

Try v4l2m2m encode raw frames could be a better idea.

from raspberrypi_webrtc.