mutable std::timed_mutex audio_mutex;
ALSAPool alsa_pool;
AudioDevice video_cards[MAX_VIDEO_CARDS]; // Under audio_mutex.
AudioDevice alsa_inputs[MAX_ALSA_CARDS]; // Under audio_mutex.
mutable std::timed_mutex audio_mutex;
ALSAPool alsa_pool;
AudioDevice video_cards[MAX_VIDEO_CARDS]; // Under audio_mutex.
AudioDevice alsa_inputs[MAX_ALSA_CARDS]; // Under audio_mutex.