8 #include <condition_variable>
22 // An interface for frame allocators; if you do not specify one
23 // (using set_video_frame_allocator), a default one that pre-allocates
24 // a freelist of eight frames using new[] will be used. Specifying
25 // your own can be useful if you have special demands for where you want the
26 // frame to end up and don't want to spend the extra copy to get it there, for
27 // instance GPU memory.
28 class FrameAllocator {
31 uint8_t *data = nullptr;
32 uint8_t *data2 = nullptr; // Only if interleaved == true.
33 size_t len = 0; // Number of bytes we actually have.
34 size_t size = 0; // Number of bytes we have room for.
36 void *userdata = nullptr;
37 FrameAllocator *owner = nullptr;
39 // If set to true, every other byte will go to data and to data2.
40 // If so, <len> and <size> are still about the number of total bytes
41 // so if size == 1024, there's 512 bytes in data and 512 in data2.
42 bool interleaved = false;
44 // At what point this frame was received. Note that this marks the
45 // _end_ of the frame being received, not the beginning.
46 // Thus, if you want to measure latency, you'll also need to include
47 // the time the frame actually took to transfer (usually 1/fps,
48 // ie., the frames are typically transferred in real time).
49 std::chrono::steady_clock::time_point received_timestamp =
50 std::chrono::steady_clock::time_point::min();
53 virtual ~FrameAllocator();
55 // Request a video frame. Note that this is called from the
56 // USB thread, which runs with realtime priority and is
57 // very sensitive to delays. Thus, you should not do anything
58 // here that might sleep, including calling malloc().
59 // (Taking a mutex is borderline.)
61 // The Frame object will be given to the frame callback,
62 // which is responsible for releasing the video frame back
63 // once it is usable for new frames (ie., it will no longer
64 // be read from). You can use the "userdata" pointer for
65 // whatever you want to identify this frame if you need to.
67 // Returning a Frame with data==nullptr is allowed;
68 // if so, the frame in progress will be dropped.
69 virtual Frame alloc_frame() = 0;
71 virtual void release_frame(Frame frame) = 0;
74 // Audio is more important than video, and also much cheaper.
75 // By having many more audio frames available, hopefully if something
76 // starts to drop, we'll have CPU load go down (from not having to
77 // process as much video) before we have to drop audio.
78 #define NUM_QUEUED_VIDEO_FRAMES 16
79 #define NUM_QUEUED_AUDIO_FRAMES 64
81 class MallocFrameAllocator : public FrameAllocator {
83 MallocFrameAllocator(size_t frame_size, size_t num_queued_frames);
84 Frame alloc_frame() override;
85 void release_frame(Frame frame) override;
90 std::mutex freelist_mutex;
91 std::stack<std::unique_ptr<uint8_t[]>> freelist; // All of size <frame_size>.
94 // Represents an input mode you can tune a card to.
97 bool autodetect = false; // If true, all the remaining fields are irrelevant.
98 unsigned width = 0, height = 0;
99 unsigned frame_rate_num = 0, frame_rate_den = 0;
100 bool interlaced = false;
103 // Represents the format of an actual frame coming in.
104 // Note: Frame rate is _frame_ rate, not field rate. So 1080i60 gets 30/1, _not_ 60/1.
105 // "second_field_start" is only valid for interlaced modes. If it is 1,
106 // the two fields are actually stored interlaced (ie., every other line).
107 // If not, each field is stored consecutively, and it signifies how many lines
108 // from the very top of the frame there are before the second field
109 // starts (so it will always be >= height/2 + extra_lines_top).
111 uint16_t id = 0; // For debugging/logging only.
112 unsigned width = 0, height = 0, second_field_start = 0;
113 unsigned extra_lines_top = 0, extra_lines_bottom = 0;
114 unsigned frame_rate_nom = 0, frame_rate_den = 0;
115 bool interlaced = false;
116 bool has_signal = false;
117 bool is_connected = true; // If false, then has_signal makes no sense.
121 uint16_t id = 0; // For debugging/logging only.
122 unsigned bits_per_sample = 0;
123 unsigned num_channels = 0;
126 typedef std::function<void(uint16_t timecode,
127 FrameAllocator::Frame video_frame, size_t video_offset, VideoFormat video_format,
128 FrameAllocator::Frame audio_frame, size_t audio_offset, AudioFormat audio_format)>
131 typedef std::function<void(libusb_device *dev)> card_connected_callback_t;
132 typedef std::function<void()> card_disconnected_callback_t;
134 class CaptureInterface {
136 virtual ~CaptureInterface() {}
138 virtual std::map<uint32_t, VideoMode> get_available_video_modes() const = 0;
139 virtual uint32_t get_current_video_mode() const = 0;
140 virtual void set_video_mode(uint32_t video_mode_id) = 0;
142 virtual std::map<uint32_t, std::string> get_available_video_inputs() const = 0;
143 virtual void set_video_input(uint32_t video_input_id) = 0;
144 virtual uint32_t get_current_video_input() const = 0;
146 virtual std::map<uint32_t, std::string> get_available_audio_inputs() const = 0;
147 virtual void set_audio_input(uint32_t audio_input_id) = 0;
148 virtual uint32_t get_current_audio_input() const = 0;
150 // Does not take ownership.
151 virtual void set_video_frame_allocator(FrameAllocator *allocator) = 0;
153 virtual FrameAllocator *get_video_frame_allocator() = 0;
155 // Does not take ownership.
156 virtual void set_audio_frame_allocator(FrameAllocator *allocator) = 0;
158 virtual FrameAllocator *get_audio_frame_allocator() = 0;
160 virtual void set_frame_callback(frame_callback_t callback) = 0;
162 // Needs to be run before configure_card().
163 virtual void set_dequeue_thread_callbacks(std::function<void()> init, std::function<void()> cleanup) = 0;
165 // Only valid after configure_card().
166 virtual std::string get_description() const = 0;
168 virtual void configure_card() = 0;
170 virtual void start_bm_capture() = 0;
172 virtual void stop_dequeue_thread() = 0;
174 // If a card is disconnected, it cannot come back; you should call stop_dequeue_thread()
176 virtual bool get_disconnected() const = 0;
179 // The actual capturing class, representing capture from a single card.
180 class BMUSBCapture : public CaptureInterface {
182 BMUSBCapture(int card_index, libusb_device *dev = nullptr)
183 : card_index(card_index), dev(dev)
189 // Note: Cards could be unplugged and replugged between this call and
190 // actually opening the card (in configure_card()).
191 static unsigned num_cards();
193 std::map<uint32_t, VideoMode> get_available_video_modes() const override;
194 uint32_t get_current_video_mode() const override;
195 void set_video_mode(uint32_t video_mode_id) override;
197 virtual std::map<uint32_t, std::string> get_available_video_inputs() const override;
198 virtual void set_video_input(uint32_t video_input_id) override;
199 virtual uint32_t get_current_video_input() const override { return current_video_input; }
201 virtual std::map<uint32_t, std::string> get_available_audio_inputs() const override;
202 virtual void set_audio_input(uint32_t audio_input_id) override;
203 virtual uint32_t get_current_audio_input() const override { return current_audio_input; }
205 // Does not take ownership.
206 void set_video_frame_allocator(FrameAllocator *allocator) override
208 video_frame_allocator = allocator;
209 if (owned_video_frame_allocator.get() != allocator) {
210 owned_video_frame_allocator.reset();
214 FrameAllocator *get_video_frame_allocator() override
216 return video_frame_allocator;
219 // Does not take ownership.
220 void set_audio_frame_allocator(FrameAllocator *allocator) override
222 audio_frame_allocator = allocator;
223 if (owned_audio_frame_allocator.get() != allocator) {
224 owned_audio_frame_allocator.reset();
228 FrameAllocator *get_audio_frame_allocator() override
230 return audio_frame_allocator;
233 void set_frame_callback(frame_callback_t callback) override
235 frame_callback = callback;
238 // Needs to be run before configure_card().
239 void set_dequeue_thread_callbacks(std::function<void()> init, std::function<void()> cleanup) override
241 dequeue_init_callback = init;
242 dequeue_cleanup_callback = cleanup;
243 has_dequeue_callbacks = true;
246 // Only valid after configure_card().
247 std::string get_description() const override {
251 void configure_card() override;
252 void start_bm_capture() override;
253 void stop_dequeue_thread() override;
254 bool get_disconnected() const override { return disconnected; }
256 // TODO: It's rather messy to have these outside the interface.
257 static void start_bm_thread();
258 static void stop_bm_thread();
260 // Hotplug event (for devices being inserted between start_bm_thread()
261 // and stop_bm_thread()); entirely optional, but must be set before
262 // start_bm_capture(). Note that your callback should do as little work
263 // as possible, since the callback comes from the main USB handling
264 // thread, which is very time-sensitive.
266 // The callback function transfers ownership. If you don't want to hold
267 // on to the device given to you in the callback, you need to call
268 // libusb_unref_device().
269 static void set_card_connected_callback(card_connected_callback_t callback,
270 bool hotplug_existing_devices_arg = false)
272 card_connected_callback = callback;
273 hotplug_existing_devices = hotplug_existing_devices_arg;
276 // Similar to set_card_connected_callback(), with the same caveats.
277 // (Note that this is set per-card and not global, as it is logically
278 // connected to an existing BMUSBCapture object.)
279 void set_card_disconnected_callback(card_disconnected_callback_t callback)
281 card_disconnected_callback = callback;
288 FrameAllocator::Frame frame;
291 void start_new_audio_block(const uint8_t *start);
292 void start_new_frame(const uint8_t *start);
294 void queue_frame(uint16_t format, uint16_t timecode, FrameAllocator::Frame frame, std::deque<QueuedFrame> *q);
295 void dequeue_thread_func();
297 static void usb_thread_func();
298 static void cb_xfr(struct libusb_transfer *xfr);
299 static int cb_hotplug(libusb_context *ctx, libusb_device *dev, libusb_hotplug_event event, void *user_data);
301 void update_capture_mode();
303 std::string description;
305 FrameAllocator::Frame current_video_frame;
306 FrameAllocator::Frame current_audio_frame;
308 std::mutex queue_lock;
309 std::condition_variable queues_not_empty;
310 std::deque<QueuedFrame> pending_video_frames;
311 std::deque<QueuedFrame> pending_audio_frames;
313 FrameAllocator *video_frame_allocator = nullptr;
314 FrameAllocator *audio_frame_allocator = nullptr;
315 std::unique_ptr<FrameAllocator> owned_video_frame_allocator;
316 std::unique_ptr<FrameAllocator> owned_audio_frame_allocator;
317 frame_callback_t frame_callback = nullptr;
318 static card_connected_callback_t card_connected_callback;
319 static bool hotplug_existing_devices;
320 card_disconnected_callback_t card_disconnected_callback = nullptr;
322 std::thread dequeue_thread;
323 std::atomic<bool> dequeue_thread_should_quit;
324 bool has_dequeue_callbacks = false;
325 std::function<void()> dequeue_init_callback = nullptr;
326 std::function<void()> dequeue_cleanup_callback = nullptr;
328 int current_register = 0;
330 static constexpr int NUM_BMUSB_REGISTERS = 60;
331 uint8_t register_file[NUM_BMUSB_REGISTERS];
333 // If <dev> is nullptr, will choose device number <card_index> from the list
334 // of available devices on the system. <dev> is not used after configure_card()
335 // (it will be unref-ed).
337 libusb_device *dev = nullptr;
339 std::vector<libusb_transfer *> iso_xfrs;
340 int assumed_frame_width = 1280;
342 libusb_device_handle *devh = nullptr;
343 uint32_t current_video_input = 0x00000000; // HDMI/SDI.
344 uint32_t current_audio_input = 0x00000000; // Embedded.
346 bool disconnected = false;