# Selective
# Forwarding
# Unit
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# Matrix SFU
### What do we need `waterfall` for?
- Scalability and efficiency for big conferences.
- Concerns of high bandwidth consumption.
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## Why Yet Another SFU?
How is it different from other SFUs?
- Signaling with Matrix.
- Cascading (SFU to SFU).
- Matrix RTC use case.
- "Dumb" SFU, "smart" clients.
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## Brief History
- Started as a Pion-based PoC from Sean Debois.
- Specs: MSC3401, MSC3898.
- Currently developed by the Element team.
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## How Does It Work?
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## Key Features
- Signaling over Matrix.
- Subscription logic over data channels.
- RTCP forwarding (PLIs).
- Simulcast (3 spatial layers for video).
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## Roadmap
- Reliability and scalability for bigger calls.
- Simulcast (done).
- Congestion control.
- Rate allocation.
- SFU selection logic.
- End-to-end media encryption.
- Cascading.
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## Thank You!
### Links
`waterfall`
MSC3401
MSC3898
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