# blax_webrtc — Rust media core

The timing-critical WebRTC media path for `blax-software/laravel-webrtc`, so that
PHP never runs per-20ms real-time DSP.

## Why Rust here

Handling **connections** concurrently in PHP is a solved problem (Swoole,
FrankenPHP, ReactPHP). What is *not* proven is sustained per-packet media DSP
(decrypt SRTP + Opus + RTP jitter every 20ms) glitch-free in single-threaded PHP.
That work belongs in a language built for it. `str0m` is **sans-IO** (no threads
or async of its own — you feed it bytes), which makes it ideal to embed and drive
from PHP.

- `str0m` owns ICE / DTLS / SRTP / RTP / Opus.
- `ext-php-rs` exposes a thin function surface to PHP.
- PHP (`Str0mMediaEngine`) forwards SDP/ICE/control across the FFI boundary and
  calls back into Laravel for persistence (recordings, transmission rows).

## Build

```bash
# one-time: cargo + the ext-php-rs helper
cargo install cargo-php

cd rust
cargo php install --release   # compiles the cdylib, installs it as the `blax_webrtc` extension
php -m | grep blax_webrtc      # verify it loaded
```

Then set `WEBRTC_MEDIA_ENGINE=BlaxSoftware\LaravelWebRtc\Media\Str0mMediaEngine`.

## Status

Scaffold. `src/lib.rs` documents the intended FFI functions
(`blax_webrtc_offer`, `..._add_ice_candidate`, `..._start_recording`,
`..._connect_peers`, `..._bridge`, `..._close`) that `Str0mMediaEngine` forwards
to. Implement them against `str0m`'s RTP/Frame API, then flip the PHP engine off
`NullMediaEngine`.