# Android Cast — implementation roadmap

## Stream protection (FEC / NACK)

| Item | Status |
|------|--------|
| GF(256) Reed–Solomon + `ProtectionEnvelope` v1 (monolithic) | Done |
| **v2 per-shard FEC** (`FecShardWire`, one ACUD message per RS shard) | Done |
| NACK + `RetransmitCache` + `MSG_NACK` | Done |
| Post-handshake negotiation | Done |
| Backward compat (defer FEC until negotiated; ignore foreign FEC/NACK) | Done |
| Default protection **NONE** (stable cast) | Done |
| Integration tests (`FecShard*`, `UdpCastTransportFecTest`) | Done |
| Lab soak under loss (HY300 / BL6000) | TODO (manual) |
| NACK rate limit / backoff | Done (`NackRateLimiter`) |
| `MSG_FEC_NACK` by groupId (optional) | Deferred |

Enable in **Settings → Stream protection (UDP)** on both sender and receiver, then reconnect.

## libvpx / Opus / Speex

| Item | Status |
|------|--------|
| `libandroidcast_codecs.so` + JNI probes | Done |
| Cross-compile `libvpx.a` (`scripts/build-native-codecs.sh`) | Done |
| JNI encode/decode in `libvpx_bridge.c` | Done (when `libvpx.a` linked per ABI) |
| `LibvpxVideoEncoderSink` (surface + buffer) | Done |
| libvpx decoder on receiver (`LibvpxCapableVideoDecoder`) | Done |
| Surface → libvpx without MediaCodec passthrough on cast | Done (ImageReader) |
| Opus / Speex build + sinks | TODO |

See [ndk/README.md](../ndk/README.md).