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git://f0xx.org/android_cast
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49 lines
2.1 KiB
Markdown
49 lines
2.1 KiB
Markdown
# Native codecs (libvpx, Opus, Speex)
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The app loads `libandroidcast_codecs.so` for availability probes and future software encode/decode paths.
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## Current status
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| Component | Java | Native | Notes |
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|-----------|------|--------|-------|
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| FEC 3/4 + RS | Yes | — | v2 **per-shard** on wire (`FecShardWire`); v1 monolithic decode still accepted |
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| NACK + retransmit cache | Yes | — | UDP `MSG_NACK`, combined with FEC when enabled |
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| libvpx VP8/VP9 | Native | Encode + decode | Screen cast via ImageReader; receiver libvpx (decoder uses `VPX_CODEC_USE_ERROR_CONCEALMENT` when supported) or MediaCodec fallback |
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| Opus / Speex | Probe + static link when `lib*.a` built | Encode/decode JNI sinks | `scripts/build-native-codecs.sh` → CMake autolink |
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## Enable native codecs (developer)
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1. Initialize submodules as needed:
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```bash
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git submodule update --init third-party/libvpx
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git submodule update --init third-party/opus
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git submodule update --init third-party/speex
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```
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2. Build static libs per ABI (NDK auto-detected via `scripts/android-ndk.sh`):
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```bash
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./scripts/build-native-codecs.sh arm64-v8a
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./scripts/build-native-codecs.sh armeabi-v7a # if shipped in APK
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```
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If the repo path has **spaces**, the script stages under `/tmp/androidcast-libvpx-$USER`.
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3. Gradle / CMake link `build/native/<abi>/lib*.a` when present and set `ANDROIDCAST_HAVE_LIBVPX`, `ANDROIDCAST_HAVE_OPUS`, `ANDROIDCAST_HAVE_SPEEX` accordingly.
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4. `./gradlew assembleDebug`
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Optional override: `ANDROIDCAST_LIBVPX_LIB` only applies when its path contains the current ABI name (e.g. `.../arm64-v8a/libvpx.a`).
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ABIs without matching `.a` files still build; missing codecs are disabled on those architectures.
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## Stream protection defaults
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- Default: **None** (no FEC/NACK)
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- Enable in **Global settings → Stream protection (UDP)**
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- After handshake, sender and receiver negotiate the effective mode (no protocol version bump)
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- Until negotiation completes, UDP protection stays **off**; peers without FEC support **ignore** protected frames
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Full checklist: [docs/ROADMAP.md](../docs/ROADMAP.md)
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