Fix Oboe native sample rate, add audio routing hints, tighten CMake symbol visibility

Co-authored-by: winnerspiros <1675249+winnerspiros@users.noreply.github.com>
Agent-Logs-Url: https://github.com/winnerspiros/osu/sessions/9d78b417-3621-444c-923d-84058d554f4b

Author: Copilot

osu.Android/Native/CMakeLists.txt

@@ -4,8 +4,8 @@ project(osu_native LANGUAGES CXX)
 set(CMAKE_CXX_STANDARD 17)
 
 # Release build optimizations for low-latency performance.
-set(CMAKE_CXX_FLAGS_RELEASE "-O2 -flto -DNDEBUG")
-set(CMAKE_C_FLAGS_RELEASE "-O2 -flto -DNDEBUG")
+set(CMAKE_CXX_FLAGS_RELEASE "-O2 -flto -fvisibility=hidden -DNDEBUG")
+set(CMAKE_C_FLAGS_RELEASE "-O2 -flto -fvisibility=hidden -DNDEBUG")
 
 find_package(oboe REQUIRED CONFIG)
 find_library(vulkan-lib vulkan)

osu.Android/Native/oboe_bridge.cpp

@@ -27,7 +27,13 @@ bool OboeBridge::open() {
            ->setSharingMode(oboe::SharingMode::Exclusive)
            ->setFormat(oboe::AudioFormat::Float)
            ->setChannelCount(oboe::ChannelCount::Stereo)
-           ->setSampleRate(48000)
+           // Let Oboe pick the device's native sample rate.
+           // Hardcoding (e.g. 48000) would force Android's SRC resampler when the
+           // device native rate differs, adding measurable latency.
+           ->setSampleRate(oboe::kUnspecified)
+           // Semantic hints help Android route through the optimal audio path.
+           ->setContentType(oboe::ContentType::Music)
+           ->setUsage(oboe::Usage::Game)
            ->setCallback(this)
            // Prefer AAudio for lowest latency (available on Android 8.1+).
            // Falls back to OpenSL ES automatically on older devices.