snap

ndk/CMakeLists.txt

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+cmake_minimum_required(VERSION 3.22.1)
+project(androidcast_codecs C)
+
+set(CMAKE_C_STANDARD 11)
+
+set(THIRD_PARTY_ROOT ${CMAKE_SOURCE_DIR}/../third-party)
+set(NDK_BRIDGE ${CMAKE_SOURCE_DIR})
+
+add_library(androidcast_codecs SHARED
+    ${NDK_BRIDGE}/jni/androidcast_codecs.c
+    ${NDK_BRIDGE}/jni/libvpx_bridge.c
+    ${NDK_BRIDGE}/jni/opus_bridge.c
+    ${NDK_BRIDGE}/jni/speex_bridge.c
+)
+
+target_include_directories(androidcast_codecs PRIVATE
+    ${NDK_BRIDGE}/jni
+)
+
+if(DEFINED ENV{ANDROIDCAST_LIBVPX_LIB} AND EXISTS "$ENV{ANDROIDCAST_LIBVPX_LIB}")
+    message(STATUS "Linking libvpx from $ENV{ANDROIDCAST_LIBVPX_LIB}")
+    target_compile_definitions(androidcast_codecs PRIVATE ANDROIDCAST_HAVE_LIBVPX=1)
+    target_link_libraries(androidcast_codecs "$ENV{ANDROIDCAST_LIBVPX_LIB}")
+elseif(EXISTS "${THIRD_PARTY_ROOT}/libvpx")
+    message(STATUS "libvpx submodule present — set ANDROIDCAST_LIBVPX_LIB to link (see ndk/README.md)")
+endif()
+
+find_library(log-lib log)
+target_link_libraries(androidcast_codecs ${log-lib})

ndk/README.md

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+# 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 | — | `ProtectionEnvelope`, handshake-safe scopes |
+| 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/` |
+
+## Enable libvpx (developer)
+
+1. `git submodule update --init third-party/libvpx`
+2. Build `libvpx.a` for your ABI (script stub: `scripts/build-native-codecs.sh`)
+3. Rebuild the APK with the static library path:
+
+```bash
+export ANDROIDCAST_LIBVPX_LIB=/path/to/libvpx.a
+./gradlew assembleDebug
+```
+
+CMake defines `ANDROIDCAST_HAVE_LIBVPX=1` and links the archive when the variable is set.
+
+## Stream protection defaults
+
+- Default: **None** (no FEC/NACK)
+- Enable in **Global settings → Stream protection (UDP)**
+- After handshake, sender and receiver negotiate the effective mode

ndk/jni/androidcast_codecs.c

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+#include <jni.h>
+#include <android/log.h>
+
+#define LOG_TAG "androidcast_codecs"
+
+JNIEXPORT jint JNI_OnLoad(JavaVM *vm, void *reserved) {
+    (void)vm;
+    (void)reserved;
+    __android_log_print(ANDROID_LOG_INFO, LOG_TAG, "androidcast codecs native library loaded");
+    return JNI_VERSION_1_6;
+}

ndk/jni/libvpx_bridge.c

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+#include <jni.h>
+#include <string.h>
+
+/* VP8/VP9 via libvpx — linked when third-party/libvpx is built into this library. */
+#ifndef ANDROIDCAST_HAVE_LIBVPX
+#define ANDROIDCAST_HAVE_LIBVPX 0
+#endif
+
+JNIEXPORT jboolean JNICALL
+Java_com_foxx_androidcast_media_codec_jni_NativeCodecBridge_nativeIsLibvpxAvailable(
+        JNIEnv *env, jclass clazz) {
+    (void)env;
+    (void)clazz;
+    return ANDROIDCAST_HAVE_LIBVPX ? JNI_TRUE : JNI_FALSE;
+}

ndk/jni/opus_bridge.c

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+#include <jni.h>
+
+#ifndef ANDROIDCAST_HAVE_OPUS
+#define ANDROIDCAST_HAVE_OPUS 0
+#endif
+
+JNIEXPORT jboolean JNICALL
+Java_com_foxx_androidcast_media_codec_jni_NativeCodecBridge_nativeIsOpusAvailable(
+        JNIEnv *env, jclass clazz) {
+    (void)env;
+    (void)clazz;
+    return ANDROIDCAST_HAVE_OPUS ? JNI_TRUE : JNI_FALSE;
+}

ndk/jni/speex_bridge.c

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+#include <jni.h>
+
+#ifndef ANDROIDCAST_HAVE_SPEEX
+#define ANDROIDCAST_HAVE_SPEEX 0
+#endif
+
+JNIEXPORT jboolean JNICALL
+Java_com_foxx_androidcast_media_codec_jni_NativeCodecBridge_nativeIsSpeexAvailable(
+        JNIEnv *env, jclass clazz) {
+    (void)env;
+    (void)clazz;
+    return ANDROIDCAST_HAVE_SPEEX ? JNI_TRUE : JNI_FALSE;
+}