6 #include <condition_variable>
14 struct libusb_transfer;
16 // An interface for frame allocators; if you do not specify one
17 // (using set_video_frame_allocator), a default one that pre-allocates
18 // a freelist of eight frames using new[] will be used. Specifying
19 // your own can be useful if you have special demands for where you want the
20 // frame to end up and don't want to spend the extra copy to get it there, for
21 // instance GPU memory.
22 class FrameAllocator {
25 uint8_t *data = nullptr;
26 uint8_t *data2 = nullptr; // Only if interleaved == true.
27 size_t len = 0; // Number of bytes we actually have.
28 size_t size = 0; // Number of bytes we have room for.
30 void *userdata = nullptr;
31 FrameAllocator *owner = nullptr;
33 // If set to true, every other byte will go to data and to data2.
34 // If so, <len> and <size> are still about the number of total bytes
35 // so if size == 1024, there's 512 bytes in data and 512 in data2.
36 bool interleaved = false;
39 virtual ~FrameAllocator();
41 // Request a video frame. Note that this is called from the
42 // USB thread, which runs with realtime priority and is
43 // very sensitive to delays. Thus, you should not do anything
44 // here that might sleep, including calling malloc().
45 // (Taking a mutex is borderline.)
47 // The Frame object will be given to the frame callback,
48 // which is responsible for releasing the video frame back
49 // once it is usable for new frames (ie., it will no longer
50 // be read from). You can use the "userdata" pointer for
51 // whatever you want to identify this frame if you need to.
53 // Returning a Frame with data==nullptr is allowed;
54 // if so, the frame in progress will be dropped.
55 virtual Frame alloc_frame() = 0;
57 virtual void release_frame(Frame frame) = 0;
60 typedef std::function<void(uint16_t timecode,
61 FrameAllocator::Frame video_frame, size_t video_offset, uint16_t video_format,
62 FrameAllocator::Frame audio_frame, size_t audio_offset, uint16_t audio_format)>
65 // The actual capturing class, representing capture from a single card.
68 BMUSBCapture(int card_index)
69 : card_index(card_index)
73 // Does not take ownership.
74 void set_video_frame_allocator(FrameAllocator *allocator)
76 video_frame_allocator = allocator;
79 FrameAllocator *get_video_frame_allocator()
81 return video_frame_allocator;
84 // Does not take ownership.
85 void set_audio_frame_allocator(FrameAllocator *allocator)
87 audio_frame_allocator = allocator;
90 FrameAllocator *get_audio_frame_allocator()
92 return audio_frame_allocator;
95 void set_frame_callback(frame_callback_t callback)
97 frame_callback = callback;
100 // Needs to be run before configure_card().
101 void set_dequeue_thread_callbacks(std::function<void()> init, std::function<void()> cleanup)
103 dequeue_init_callback = init;
104 dequeue_cleanup_callback = cleanup;
105 has_dequeue_callbacks = true;
108 // Only valid after configure_card().
109 std::string get_description() const {
113 void configure_card();
114 void start_bm_capture();
115 void stop_dequeue_thread();
117 static void start_bm_thread();
118 static void stop_bm_thread();
124 FrameAllocator::Frame frame;
127 void start_new_audio_block(const uint8_t *start);
128 void start_new_frame(const uint8_t *start);
130 void queue_frame(uint16_t format, uint16_t timecode, FrameAllocator::Frame frame, std::deque<QueuedFrame> *q);
131 void dequeue_thread_func();
133 static void usb_thread_func();
134 static void cb_xfr(struct libusb_transfer *xfr);
136 std::string description;
138 FrameAllocator::Frame current_video_frame;
139 FrameAllocator::Frame current_audio_frame;
141 std::mutex queue_lock;
142 std::condition_variable queues_not_empty;
143 std::deque<QueuedFrame> pending_video_frames;
144 std::deque<QueuedFrame> pending_audio_frames;
146 FrameAllocator *video_frame_allocator = nullptr;
147 FrameAllocator *audio_frame_allocator = nullptr;
148 frame_callback_t frame_callback = nullptr;
150 std::thread dequeue_thread;
151 std::atomic<bool> dequeue_thread_should_quit;
152 bool has_dequeue_callbacks = false;
153 std::function<void()> dequeue_init_callback = nullptr;
154 std::function<void()> dequeue_cleanup_callback = nullptr;
156 int current_register = 0;
158 static constexpr int NUM_BMUSB_REGISTERS = 60;
159 uint8_t register_file[NUM_BMUSB_REGISTERS];
162 std::vector<libusb_transfer *> iso_xfrs;
163 int assumed_frame_width = 1280;
166 // Get details for the given video format; returns false if detection was incomplete.
167 // Note: Frame rate is _frame_ rate, not field rate. So 1080i60 gets 30/1, _not_ 60/1.
168 // "second_field_start" is only valid for interlaced modes; it signifies
169 // how many lines from the very top of the frame there are before the second field
170 // starts (so it will always be >= height/2 + extra_lines_top).
171 bool decode_video_format(uint16_t video_format, unsigned *width, unsigned *height, unsigned *second_field_start,
172 unsigned *extra_lines_top, unsigned *extra_lines_bottom,
173 unsigned *frame_rate_nom, unsigned *frame_rate_den, bool *interlaced);