# FLV saver example

The `rtmp` library deliberately stops at delivering frames — no recording,
HLS or relaying built in. This example shows what "the rest" looks like for
the simplest possible case: write every published stream to an FLV file.

It's about 70 lines (`lib/flv_saver.ex`), and almost all of it is the FLV
container format. RTMP message payloads are already FLV tag bodies, so each
frame is written as-is with a small header in front.

## Run it

```sh
cd examples/flv_saver
mix deps.get
RTMP_PORT=1935 OUTPUT_DIR=recordings mix run --no-halt
```

Publish to it from another terminal:

```sh
ffmpeg -re -f lavfi -i testsrc=size=640x360:rate=30 \
       -f lavfi -i sine=frequency=440 -t 10 \
       -c:v libx264 -c:a aac -f flv rtmp://localhost:1935/live/mystream
```

or from OBS: server `rtmp://localhost:1935/live`, stream key `mystream`.

You'll get `recordings/mystream-<unix time>.flv`, playable in VLC or
`ffplay`, and inspectable with `ffprobe`.

## Things to notice

- **The stream key is validated before it touches a path.** It comes from
  the network; `../../etc/passwd` must not become a filename. Keys that
  aren't `[A-Za-z0-9_-]{1,64}` are rejected in `handle_publish/3`.
- **No auth.** Any valid-looking key is accepted. A real server checks keys
  against something in `handle_publish/3`.
- **Writes are synchronous.** If the disk is slow, the publisher is slowed
  down by TCP flow control — that's the library's backpressure working, not
  a bug.