-};
-
-// The class dealing with the collective of all ALSA cards in the system.
-// In particular, it deals with enumeration of cards, and hotplug of new ones.
-class ALSAPool {
-public:
- ~ALSAPool();
-
- struct Device {
- enum class State {
- // There is no card here. (There probably used to be one,
- // but it got removed.) We don't insert a card before
- // we've actually probed it, ie., we know whether it
- // can be captured from at all, and what its name is.
- EMPTY,
-
- // This card is ready for capture, as far as we know.
- // (It could still be used by someone else; we don't know
- // until we try to open it.)
- READY,
-
- // We are trying to start capture from this card, but we are not
- // streaming yet. Note that this could in theory go on forever,
- // if the card is in use by some other process; in the UI,
- // we will show this state as “(busy)”.
- STARTING,
-
- // The card is capturing and sending data. If there's a fatal error,
- // it could go back to STARTING, or it could go to DEAD
- // (depending on the error).
- RUNNING,
-
- // The card is gone (e.g., unplugged). However, since there's
- // still a bus using it, we can't just remove the entry.
- // If the card comes back (ie., a new card is plugged in,
- // and we believe it has the same configuration), it could be
- // installed in place of this card, and then presumably be put
- // back into STARTING or RUNNING.
- DEAD
- } state;
-
- std::string address; // E.g. “hw:0,0”.
- std::string name, info;
- unsigned num_channels;
- ALSAInput *input = nullptr; // nullptr iff EMPTY or DEAD.
-
- // Whether the AudioMixer is interested in this card or not.
- // “Interested” could mean either of two things: Either it is part of
- // a bus mapping, or it is in the process of enumerating devices
- // (to show to the user). A card that is _not_ held can disappear
- // at any given time as a result of an error or hotplug event;
- // a card that is held will go to the DEAD state instead.
- bool held = false;
- };
-
- void init();
-
- // Get the list of all current devices. Note that this will implicitly mark
- // all of the returned devices as held, since the input mapping UI needs
- // some kind of stability when the user is to choose. Thus, when you are done
- // with the list and have set a new mapping, you must go through all the devices
- // you don't want and release them using release_device().
- std::vector<Device> get_devices();
-
- void hold_device(unsigned index);
- void release_device(unsigned index); // Note: index is allowed to go out of bounds.
-
- // If device is held, start or restart capture. If device is not held,
- // stop capture if it isn't already.
- void reset_device(unsigned index);
-
- // Note: The card must be held. Returns OUTPUT_FREQUENCY if the card is in EMPTY or DEAD.
- unsigned get_capture_frequency(unsigned index);
-
- // TODO: Add accessors and/or callbacks about changed state, so that
- // the UI actually stands a chance in using that information.
-
-private:
- mutable std::mutex mu;
- std::vector<Device> devices; // Under mu.
- std::vector<std::unique_ptr<ALSAInput>> inputs; // Under mu, corresponds 1:1 to devices.
-
- void enumerate_devices();
- bool add_device(unsigned card_index, unsigned dev_index);