static std::optional< RtAudio::Api > s_preferred_api
Preferred RtAudio API, if specified.
static std::unique_ptr< RtAudio > s_instance
Singleton instance of the RtAudio driver (nullptr until first access)
static bool s_stream_open
Stream state flag to enforce exclusive stream ownership.
static std::mutex s_mutex
Synchronization primitive for thread-safe access to the singleton.