6 #include <condition_variable>
16 struct libusb_transfer;
18 // An interface for frame allocators; if you do not specify one
19 // (using set_video_frame_allocator), a default one that pre-allocates
20 // a freelist of eight frames using new[] will be used. Specifying
21 // your own can be useful if you have special demands for where you want the
22 // frame to end up and don't want to spend the extra copy to get it there, for
23 // instance GPU memory.
24 class FrameAllocator {
27 uint8_t *data = nullptr;
28 uint8_t *data2 = nullptr; // Only if interleaved == true.
29 size_t len = 0; // Number of bytes we actually have.
30 size_t size = 0; // Number of bytes we have room for.
32 void *userdata = nullptr;
33 FrameAllocator *owner = nullptr;
35 // If set to true, every other byte will go to data and to data2.
36 // If so, <len> and <size> are still about the number of total bytes
37 // so if size == 1024, there's 512 bytes in data and 512 in data2.
38 bool interleaved = false;
41 virtual ~FrameAllocator();
43 // Request a video frame. Note that this is called from the
44 // USB thread, which runs with realtime priority and is
45 // very sensitive to delays. Thus, you should not do anything
46 // here that might sleep, including calling malloc().
47 // (Taking a mutex is borderline.)
49 // The Frame object will be given to the frame callback,
50 // which is responsible for releasing the video frame back
51 // once it is usable for new frames (ie., it will no longer
52 // be read from). You can use the "userdata" pointer for
53 // whatever you want to identify this frame if you need to.
55 // Returning a Frame with data==nullptr is allowed;
56 // if so, the frame in progress will be dropped.
57 virtual Frame alloc_frame() = 0;
59 virtual void release_frame(Frame frame) = 0;
62 // Audio is more important than video, and also much cheaper.
63 // By having many more audio frames available, hopefully if something
64 // starts to drop, we'll have CPU load go down (from not having to
65 // process as much video) before we have to drop audio.
66 #define NUM_QUEUED_VIDEO_FRAMES 16
67 #define NUM_QUEUED_AUDIO_FRAMES 64
69 class MallocFrameAllocator : public FrameAllocator {
71 MallocFrameAllocator(size_t frame_size, size_t num_queued_frames);
72 Frame alloc_frame() override;
73 void release_frame(Frame frame) override;
78 std::mutex freelist_mutex;
79 std::stack<std::unique_ptr<uint8_t[]>> freelist; // All of size <frame_size>.
82 // Represents an input mode you can tune a card to.
85 bool autodetect = false; // If true, all the remaining fields are irrelevant.
86 unsigned width = 0, height = 0;
87 unsigned frame_rate_num = 0, frame_rate_den = 0;
88 bool interlaced = false;
91 // Represents the format of an actual frame coming in.
93 uint16_t id = 0; // For debugging/logging only.
94 unsigned width = 0, height = 0, second_field_start = 0;
95 unsigned extra_lines_top = 0, extra_lines_bottom = 0;
96 unsigned frame_rate_nom = 0, frame_rate_den = 0;
97 bool interlaced = false;
98 bool has_signal = false;
102 uint16_t id = 0; // For debugging/logging only.
103 unsigned bits_per_sample = 0;
104 unsigned num_channels = 0;
107 typedef std::function<void(uint16_t timecode,
108 FrameAllocator::Frame video_frame, size_t video_offset, VideoFormat video_format,
109 FrameAllocator::Frame audio_frame, size_t audio_offset, AudioFormat audio_format)>
112 class CaptureInterface {
114 virtual ~CaptureInterface() {}
116 virtual std::map<uint32_t, VideoMode> get_available_video_modes() const = 0;
117 virtual uint32_t get_current_video_mode() const = 0;
118 virtual void set_video_mode(uint32_t video_mode_id) = 0;
120 // Does not take ownership.
121 virtual void set_video_frame_allocator(FrameAllocator *allocator) = 0;
123 virtual FrameAllocator *get_video_frame_allocator() = 0;
125 // Does not take ownership.
126 virtual void set_audio_frame_allocator(FrameAllocator *allocator) = 0;
128 virtual FrameAllocator *get_audio_frame_allocator() = 0;
130 virtual void set_frame_callback(frame_callback_t callback) = 0;
132 // Needs to be run before configure_card().
133 virtual void set_dequeue_thread_callbacks(std::function<void()> init, std::function<void()> cleanup) = 0;
135 // Only valid after configure_card().
136 virtual std::string get_description() const = 0;
138 virtual void configure_card() = 0;
140 virtual void start_bm_capture() = 0;
142 virtual void stop_dequeue_thread() = 0;
145 // The actual capturing class, representing capture from a single card.
146 class BMUSBCapture : public CaptureInterface {
148 BMUSBCapture(int card_index)
149 : card_index(card_index)
155 std::map<uint32_t, VideoMode> get_available_video_modes() const override;
156 uint32_t get_current_video_mode() const override;
157 void set_video_mode(uint32_t video_mode_id) override;
159 // Does not take ownership.
160 void set_video_frame_allocator(FrameAllocator *allocator) override
162 video_frame_allocator = allocator;
165 FrameAllocator *get_video_frame_allocator() override
167 return video_frame_allocator;
170 // Does not take ownership.
171 void set_audio_frame_allocator(FrameAllocator *allocator) override
173 audio_frame_allocator = allocator;
176 FrameAllocator *get_audio_frame_allocator() override
178 return audio_frame_allocator;
181 void set_frame_callback(frame_callback_t callback) override
183 frame_callback = callback;
186 // Needs to be run before configure_card().
187 void set_dequeue_thread_callbacks(std::function<void()> init, std::function<void()> cleanup) override
189 dequeue_init_callback = init;
190 dequeue_cleanup_callback = cleanup;
191 has_dequeue_callbacks = true;
194 // Only valid after configure_card().
195 std::string get_description() const override {
199 void configure_card() override;
200 void start_bm_capture() override;
201 void stop_dequeue_thread() override;
203 // TODO: It's rather messy to have these outside the interface.
204 static void start_bm_thread();
205 static void stop_bm_thread();
211 FrameAllocator::Frame frame;
214 void start_new_audio_block(const uint8_t *start);
215 void start_new_frame(const uint8_t *start);
217 void queue_frame(uint16_t format, uint16_t timecode, FrameAllocator::Frame frame, std::deque<QueuedFrame> *q);
218 void dequeue_thread_func();
220 static void usb_thread_func();
221 static void cb_xfr(struct libusb_transfer *xfr);
223 std::string description;
225 FrameAllocator::Frame current_video_frame;
226 FrameAllocator::Frame current_audio_frame;
228 std::mutex queue_lock;
229 std::condition_variable queues_not_empty;
230 std::deque<QueuedFrame> pending_video_frames;
231 std::deque<QueuedFrame> pending_audio_frames;
233 FrameAllocator *video_frame_allocator = nullptr;
234 FrameAllocator *audio_frame_allocator = nullptr;
235 frame_callback_t frame_callback = nullptr;
237 std::thread dequeue_thread;
238 std::atomic<bool> dequeue_thread_should_quit;
239 bool has_dequeue_callbacks = false;
240 std::function<void()> dequeue_init_callback = nullptr;
241 std::function<void()> dequeue_cleanup_callback = nullptr;
243 int current_register = 0;
245 static constexpr int NUM_BMUSB_REGISTERS = 60;
246 uint8_t register_file[NUM_BMUSB_REGISTERS];
249 std::vector<libusb_transfer *> iso_xfrs;
250 int assumed_frame_width = 1280;
253 // Get details for the given video format; returns false if detection was incomplete.
254 // Note: Frame rate is _frame_ rate, not field rate. So 1080i60 gets 30/1, _not_ 60/1.
255 // "second_field_start" is only valid for interlaced modes; it signifies
256 // how many lines from the very top of the frame there are before the second field
257 // starts (so it will always be >= height/2 + extra_lines_top).
258 bool decode_video_format(uint16_t video_format, VideoFormat *decoded_video_format);