Native codecs (libvpx, Opus, Speex)

The app loads libandroidcast_codecs.so for availability probes and future software encode/decode paths.

Current status

Component	Java	Native	Notes
FEC 3/4 + RS	Yes	—	v2 per-shard on wire (`FecShardWire`); v1 monolithic decode still accepted
NACK + retransmit cache	Yes	—	UDP `MSG_NACK`, combined with FEC when enabled
libvpx VP8/VP9	Stub	Probe only	HW passthrough until `ANDROIDCAST_LIBVPX_LIB` is linked
Opus / Speex	Stub	Probe only	Submodules under `third-party/`

git submodule update --init third-party/libvpx
Build libvpx.a for your ABI: ./scripts/build-native-codecs.sh arm64-v8a
(If the repo path has spaces, the script uses /tmp/androidcast-libvpx-$USER automatically.)
Build each ABI you ship (Gradle links build/native/<abi>/libvpx.a automatically):

./scripts/build-native-codecs.sh arm64-v8a
./scripts/build-native-codecs.sh armeabi-v7a   # if armeabi-v7a is in your APK
./gradlew assembleDebug

Optional override: ANDROIDCAST_LIBVPX_LIB only applies when its path contains the current ABI name (e.g. .../arm64-v8a/libvpx.a).

ABIs without a matching libvpx.a still build; software VPx is disabled on those architectures.

Default: None (no FEC/NACK)
Enable in Global settings → Stream protection (UDP)
After handshake, sender and receiver negotiate the effective mode (no protocol version bump)
Until negotiation completes, UDP protection stays off; peers without FEC support ignore protected frames

Full checklist: docs/ROADMAP.md