Support hotplugging existing devices.

[bmusb] / bmusb / bmusb.h

#ifndef _BMUSB_H
#define _BMUSB_H

#include <libusb.h>
#include <stdint.h>
#include <atomic>
#include <condition_variable>
#include <deque>
#include <functional>
#include <map>
#include <mutex>
#include <stack>
#include <string>
#include <thread>
#include <vector>

namespace bmusb {

class BMUSBCapture;

// An interface for frame allocators; if you do not specify one
// (using set_video_frame_allocator), a default one that pre-allocates
// a freelist of eight frames using new[] will be used. Specifying
// your own can be useful if you have special demands for where you want the
// frame to end up and don't want to spend the extra copy to get it there, for
// instance GPU memory.
class FrameAllocator {
 public:
        struct Frame {
                uint8_t *data = nullptr;
                uint8_t *data2 = nullptr;  // Only if interleaved == true.
                size_t len = 0;  // Number of bytes we actually have.
                size_t size = 0;  // Number of bytes we have room for.
                size_t overflow = 0;
                void *userdata = nullptr;
                FrameAllocator *owner = nullptr;

                // If set to true, every other byte will go to data and to data2.
                // If so, <len> and <size> are still about the number of total bytes
                // so if size == 1024, there's 512 bytes in data and 512 in data2.
                bool interleaved = false;
        };

        virtual ~FrameAllocator();

        // Request a video frame. Note that this is called from the
        // USB thread, which runs with realtime priority and is
        // very sensitive to delays. Thus, you should not do anything
        // here that might sleep, including calling malloc().
        // (Taking a mutex is borderline.)
        //
        // The Frame object will be given to the frame callback,
        // which is responsible for releasing the video frame back
        // once it is usable for new frames (ie., it will no longer
        // be read from). You can use the "userdata" pointer for
        // whatever you want to identify this frame if you need to.
        //
        // Returning a Frame with data==nullptr is allowed;
        // if so, the frame in progress will be dropped.
        virtual Frame alloc_frame() = 0;

        virtual void release_frame(Frame frame) = 0;
};

// Audio is more important than video, and also much cheaper.
// By having many more audio frames available, hopefully if something
// starts to drop, we'll have CPU load go down (from not having to
// process as much video) before we have to drop audio.
#define NUM_QUEUED_VIDEO_FRAMES 16
#define NUM_QUEUED_AUDIO_FRAMES 64

class MallocFrameAllocator : public FrameAllocator {
public:
        MallocFrameAllocator(size_t frame_size, size_t num_queued_frames);
        Frame alloc_frame() override;
        void release_frame(Frame frame) override;

private:
        size_t frame_size;

        std::mutex freelist_mutex;
        std::stack<std::unique_ptr<uint8_t[]>> freelist;  // All of size <frame_size>.
};

// Represents an input mode you can tune a card to.
struct VideoMode {
        std::string name;
        bool autodetect = false;  // If true, all the remaining fields are irrelevant.
        unsigned width = 0, height = 0;
        unsigned frame_rate_num = 0, frame_rate_den = 0;
        bool interlaced = false;
};

// Represents the format of an actual frame coming in.
// Note: Frame rate is _frame_ rate, not field rate. So 1080i60 gets 30/1, _not_ 60/1.
// "second_field_start" is only valid for interlaced modes; it signifies
// how many lines from the very top of the frame there are before the second field
// starts (so it will always be >= height/2 + extra_lines_top).
struct VideoFormat {
        uint16_t id = 0;  // For debugging/logging only.
        unsigned width = 0, height = 0, second_field_start = 0;
        unsigned extra_lines_top = 0, extra_lines_bottom = 0;
        unsigned frame_rate_nom = 0, frame_rate_den = 0;
        bool interlaced = false;
        bool has_signal = false;
        bool is_connected = true;  // If false, then has_signal makes no sense.
};

struct AudioFormat {
        uint16_t id = 0;  // For debugging/logging only.
        unsigned bits_per_sample = 0;
        unsigned num_channels = 0;
};

typedef std::function<void(uint16_t timecode,
                           FrameAllocator::Frame video_frame, size_t video_offset, VideoFormat video_format,
                           FrameAllocator::Frame audio_frame, size_t audio_offset, AudioFormat audio_format)>
        frame_callback_t;

typedef std::function<void(libusb_device *dev)> card_connected_callback_t;
typedef std::function<void()> card_disconnected_callback_t;

class CaptureInterface {
 public:
        virtual ~CaptureInterface() {}

        virtual std::map<uint32_t, VideoMode> get_available_video_modes() const = 0;
        virtual uint32_t get_current_video_mode() const = 0;
        virtual void set_video_mode(uint32_t video_mode_id) = 0;

        virtual std::map<uint32_t, std::string> get_available_video_inputs() const = 0;
        virtual void set_video_input(uint32_t video_input_id) = 0;
        virtual uint32_t get_current_video_input() const = 0;

        virtual std::map<uint32_t, std::string> get_available_audio_inputs() const = 0;
        virtual void set_audio_input(uint32_t audio_input_id) = 0;
        virtual uint32_t get_current_audio_input() const = 0;

        // Does not take ownership.
        virtual void set_video_frame_allocator(FrameAllocator *allocator) = 0;

        virtual FrameAllocator *get_video_frame_allocator() = 0;

        // Does not take ownership.
        virtual void set_audio_frame_allocator(FrameAllocator *allocator) = 0;

        virtual FrameAllocator *get_audio_frame_allocator() = 0;

        virtual void set_frame_callback(frame_callback_t callback) = 0;

        // Needs to be run before configure_card().
        virtual void set_dequeue_thread_callbacks(std::function<void()> init, std::function<void()> cleanup) = 0;

        // Only valid after configure_card().
        virtual std::string get_description() const = 0;

        virtual void configure_card() = 0;

        virtual void start_bm_capture() = 0;

        virtual void stop_dequeue_thread() = 0;

        // If a card is disconnected, it cannot come back; you should call stop_dequeue_thread()
        // and delete it.
        virtual bool get_disconnected() const = 0;
};

// The actual capturing class, representing capture from a single card.
class BMUSBCapture : public CaptureInterface {
 public:
        BMUSBCapture(int card_index, libusb_device *dev = nullptr)
                : card_index(card_index), dev(dev)
        {
        }

        ~BMUSBCapture() {}

        std::map<uint32_t, VideoMode> get_available_video_modes() const override;
        uint32_t get_current_video_mode() const override;
        void set_video_mode(uint32_t video_mode_id) override;

        virtual std::map<uint32_t, std::string> get_available_video_inputs() const override;
        virtual void set_video_input(uint32_t video_input_id) override;
        virtual uint32_t get_current_video_input() const override { return current_video_input; }

        virtual std::map<uint32_t, std::string> get_available_audio_inputs() const override;
        virtual void set_audio_input(uint32_t audio_input_id) override;
        virtual uint32_t get_current_audio_input() const override { return current_audio_input; }

        // Does not take ownership.
        void set_video_frame_allocator(FrameAllocator *allocator) override
        {
                video_frame_allocator = allocator;
                if (owned_video_frame_allocator.get() != allocator) {
                        owned_video_frame_allocator.reset();
                }
        }

        FrameAllocator *get_video_frame_allocator() override
        {
                return video_frame_allocator;
        }

        // Does not take ownership.
        void set_audio_frame_allocator(FrameAllocator *allocator) override
        {
                audio_frame_allocator = allocator;
                if (owned_audio_frame_allocator.get() != allocator) {
                        owned_audio_frame_allocator.reset();
                }
        }

        FrameAllocator *get_audio_frame_allocator() override
        {
                return audio_frame_allocator;
        }

        void set_frame_callback(frame_callback_t callback) override
        {
                frame_callback = callback;
        }

        // Needs to be run before configure_card().
        void set_dequeue_thread_callbacks(std::function<void()> init, std::function<void()> cleanup) override
        {
                dequeue_init_callback = init;
                dequeue_cleanup_callback = cleanup;
                has_dequeue_callbacks = true;
        }

        // Only valid after configure_card().
        std::string get_description() const override {
                return description;
        }

        void configure_card() override;
        void start_bm_capture() override;
        void stop_dequeue_thread() override;
        bool get_disconnected() const override { return disconnected; }

        // TODO: It's rather messy to have these outside the interface.
        static void start_bm_thread();
        static void stop_bm_thread();

        // Hotplug event (for devices being inserted between start_bm_thread()
        // and stop_bm_thread()); entirely optional, but must be set before
        // start_bm_capture(). Note that your callback should do as little work
        // as possible, since the callback comes from the main USB handling
        // thread, which is very time-sensitive.
        //
        // The callback function transfers ownership. If you don't want to hold
        // on to the device given to you in the callback, you need to call
        // libusb_unref_device().
        static void set_card_connected_callback(card_connected_callback_t callback,
                                                bool hotplug_existing_devices_arg = false)
        {
                card_connected_callback = callback;
                hotplug_existing_devices = hotplug_existing_devices_arg;
        }

        // Similar to set_card_connected_callback(), with the same caveats.
        // (Note that this is set per-card and not global, as it is logically
        // connected to an existing BMUSBCapture object.)
        void set_card_disconnected_callback(card_disconnected_callback_t callback)
        {
                card_disconnected_callback = callback;
        }

 private:
        struct QueuedFrame {
                uint16_t timecode;
                uint16_t format;
                FrameAllocator::Frame frame;
        };

        void start_new_audio_block(const uint8_t *start);
        void start_new_frame(const uint8_t *start);

        void queue_frame(uint16_t format, uint16_t timecode, FrameAllocator::Frame frame, std::deque<QueuedFrame> *q);
        void dequeue_thread_func();

        static void usb_thread_func();
        static void cb_xfr(struct libusb_transfer *xfr);
        static int cb_hotplug(libusb_context *ctx, libusb_device *dev, libusb_hotplug_event event, void *user_data);

        void update_capture_mode();

        std::string description;

        FrameAllocator::Frame current_video_frame;
        FrameAllocator::Frame current_audio_frame;

        std::mutex queue_lock;
        std::condition_variable queues_not_empty;
        std::deque<QueuedFrame> pending_video_frames;
        std::deque<QueuedFrame> pending_audio_frames;

        FrameAllocator *video_frame_allocator = nullptr;
        FrameAllocator *audio_frame_allocator = nullptr;
        std::unique_ptr<FrameAllocator> owned_video_frame_allocator;
        std::unique_ptr<FrameAllocator> owned_audio_frame_allocator;
        frame_callback_t frame_callback = nullptr;
        static card_connected_callback_t card_connected_callback;
        static bool hotplug_existing_devices;
        card_disconnected_callback_t card_disconnected_callback = nullptr;

        std::thread dequeue_thread;
        std::atomic<bool> dequeue_thread_should_quit;
        bool has_dequeue_callbacks = false;
        std::function<void()> dequeue_init_callback = nullptr;
        std::function<void()> dequeue_cleanup_callback = nullptr;

        int current_register = 0;

        static constexpr int NUM_BMUSB_REGISTERS = 60;
        uint8_t register_file[NUM_BMUSB_REGISTERS];

        // If <dev> is nullptr, will choose device number <card_index> from the list
        // of available devices on the system. <dev> is not used after configure_card()
        // (it will be unref-ed).
        int card_index = -1;
        libusb_device *dev = nullptr;

        std::vector<libusb_transfer *> iso_xfrs;
        int assumed_frame_width = 1280;

        libusb_device_handle *devh = nullptr;
        uint32_t current_video_input = 0x00000000;  // HDMI/SDI.
        uint32_t current_audio_input = 0x00000000;  // Embedded.

        bool disconnected = false;
};

}  // namespace bmusb

#endif