WiFiBroadcast is an opensource digital FPV and telemetry system.
Main features:
- 1:1 map RTP to IEEE80211 packets for minimum latency (doesn't serialize to byte steam)
- Smart FEC support (immediately yeild packet to video decoder if FEC pipeline doesn't have gaps)
- Stream encryption and authentication (libsodium)
- Distributed operation. It can gather data from cards on different hosts. So you don't limited to bandwidth of single USB bus.
- Aggreagation of mavlink packets. Doesn't send wifi packet for every mavlink packet.
- Enhanced OSD for Raspberry PI (consume 10% CPU on PI Zero)
Compatible with any screen resolution. Supports aspect correction for PAL to HD scaling.
PX4 HOWTO (now a bit outdated, pull request already sent)
FAQ
Q: What is a difference from original wifibroadcast?
A: Original version of wifibroadcast use a byte-stream as input and splits it to packets of fixed size (1024 by default). If radio packet was lost and this is not corrected by FEC you'll got a hole at random (unexpected) place of stream. This is especially bad if data protocol is not resistent to (was not desired for) such random erasures. So i've rewrite it to use UDP as data source and pack one source UDP packet into one radio packet. Radio packets now have variable size depends on payload size. This is reduces a video latency a lot.
Q: What type of data can be transmitted using wifibroadcast?
A: Any UDP with packet size <= 1466. For example x264 inside RTP or Mavlink.
Q: What are transmission guarancies?
A: Wifibrodcast use FEC (forward error correction) which can recover 4 lost packets from 12 packets block with default settings. You can tune it (both TX and RX simultaniuosly!) to fit your needs.
TODO
1. Write user docs and make prebuild packages. Pull requests are welcome.
2. Do a flight test with different cards/antennas.
3. Investigate how to set TX power without CRDA hacks.
4. Tune FEC for optimal latency/redundancy.
5. Inject packets with radio link RSSI to mavlink stream
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