From 010ae7899278eef5cdfc65cb15913e9251685508 Mon Sep 17 00:00:00 2001
From: Graham King <graham@gkgk.org>
Date: Wed, 10 Mar 2021 15:52:14 -0800
Subject: [PATCH] Initial FAQ (#461)

---
 FAQ.md    | 31 +++++++++++++++++++++++++++++++
 README.md |  7 ++++++-
 2 files changed, 37 insertions(+), 1 deletion(-)
 create mode 100644 FAQ.md

diff --git a/FAQ.md b/FAQ.md
new file mode 100644
index 000000000..5dffe3e4b
--- /dev/null
+++ b/FAQ.md
@@ -0,0 +1,31 @@
+# Frequenty Asked Questions
+
+### How can I join a session receive-only, without sending any media?
+
+If you are using [ion-sdk-js](https://github.com/pion/ion-sdk-js) this should work by default. If not, read on.
+
+If a participant does not have a microphone or camera, or denies access to them from the browser, how can they join? Something needs to be added to the publisher connection to generate valid SDP.
+
+Add a datachannel to the publisher peer connection. e.g. `this.publisher.createDataChannel("ion-sfu")`
+
+### Does ion-sfu support audio level indication, telling me who is talking?
+
+Yes. The subscriber peer connection will contain a data channel. It gets sent an array of stream id that are making noise, ordered loudest first.
+
+Stream id is the `msid` from the SDP, [defined here](https://tools.ietf.org/html/draft-ietf-mmusic-msid-17). It is up to your application to map that to a meaningful value, such as the user's name.
+
+Here is an example in Typescript:
+```
+subscriber.ondatachannel = (e: RTCDataChannelEvent) => {
+	e.channel.onmessage = (e: MessageEvent) => {
+		this.mySpeakingCallback(JSON.parse(e.data));
+	}
+}
+```
+
+Audio level indication can be tuned [here in the configuration file](https://github.com/pion/ion-sfu/blob/master/config.toml#L15-L28).
+
+### Can I record the audio and/or video to disk?
+
+Recording (and general audio/video processing) is provided by separate project [ion-avp](https://github.com/pion/ion-avp/).
+
diff --git a/README.md b/README.md
index a38b01312..e07f2e2bd 100644
--- a/README.md
+++ b/README.md
@@ -20,6 +20,7 @@ A [selective forwarding unit](https://webrtcglossary.com/sfu/) is a video routin
 * Congestion Control (TWCC, REMB, RR/SR)
 * Unified plan semantics
 * Pub/Sub Peer Connection (`O(n)` port usage)
+* Audio level indication (RFC6464). "X is speaking"
 
 ## Quickstart
 
@@ -66,6 +67,10 @@ go build ./cmd/signal/grpc/main.go && ./main -c config.toml
 docker run -p 50051:50051 -p 5000-5200:5000-5200/udp pionwebrtc/ion-sfu:latest-grpc
 ```
 
+## Documentation
+
+Answers to some [Frequenty Asked Questions](FAQ.md).
+
 ## Examples
 
 To see some other ways of interacting with the ion-sfu instance, check out our [examples](examples).
@@ -84,7 +89,7 @@ MIT License - see [LICENSE](LICENSE) for full text
 
 Generate the protocol buffers and grpc code:
  1. Best choice (uses docker): `make protos`.
- 2. Manually: 
+ 2. Manually:
      - Install protocol buffers and the protcol buffers compiler. On Fedora `dnf install protobuf protobuf-compiler`.
      - `go get google.golang.org/grpc/cmd/protoc-gen-go-grpc`
      - `go get google.golang.org/protobuf/cmd/protoc-gen-go`