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;
61 uint16_t id = 0; // For debugging/logging only.
62 unsigned width = 0, height = 0, second_field_start = 0;
63 unsigned extra_lines_top = 0, extra_lines_bottom = 0;
64 unsigned frame_rate_nom = 0, frame_rate_den = 0;
65 bool interlaced = false;
66 bool has_signal = false;
69 typedef std::function<void(uint16_t timecode,
70 FrameAllocator::Frame video_frame, size_t video_offset, VideoFormat video_format,
71 FrameAllocator::Frame audio_frame, size_t audio_offset, uint16_t audio_format)>
74 class CaptureInterface {
76 virtual ~CaptureInterface() {}
78 // Does not take ownership.
79 virtual void set_video_frame_allocator(FrameAllocator *allocator) = 0;
81 virtual FrameAllocator *get_video_frame_allocator() = 0;
83 // Does not take ownership.
84 virtual void set_audio_frame_allocator(FrameAllocator *allocator) = 0;
86 virtual FrameAllocator *get_audio_frame_allocator() = 0;
88 virtual void set_frame_callback(frame_callback_t callback) = 0;
90 // Needs to be run before configure_card().
91 virtual void set_dequeue_thread_callbacks(std::function<void()> init, std::function<void()> cleanup) = 0;
93 // Only valid after configure_card().
94 virtual std::string get_description() const = 0;
96 virtual void configure_card() = 0;
98 virtual void start_bm_capture() = 0;
100 virtual void stop_dequeue_thread() = 0;
103 // The actual capturing class, representing capture from a single card.
104 class BMUSBCapture : public CaptureInterface {
106 BMUSBCapture(int card_index)
107 : card_index(card_index)
113 // Does not take ownership.
114 void set_video_frame_allocator(FrameAllocator *allocator) override
116 video_frame_allocator = allocator;
119 FrameAllocator *get_video_frame_allocator() override
121 return video_frame_allocator;
124 // Does not take ownership.
125 void set_audio_frame_allocator(FrameAllocator *allocator) override
127 audio_frame_allocator = allocator;
130 FrameAllocator *get_audio_frame_allocator() override
132 return audio_frame_allocator;
135 void set_frame_callback(frame_callback_t callback) override
137 frame_callback = callback;
140 // Needs to be run before configure_card().
141 void set_dequeue_thread_callbacks(std::function<void()> init, std::function<void()> cleanup) override
143 dequeue_init_callback = init;
144 dequeue_cleanup_callback = cleanup;
145 has_dequeue_callbacks = true;
148 // Only valid after configure_card().
149 std::string get_description() const override {
153 void configure_card() override;
154 void start_bm_capture() override;
155 void stop_dequeue_thread() override;
157 // TODO: It's rather messy to have these outside the interface.
158 static void start_bm_thread();
159 static void stop_bm_thread();
165 FrameAllocator::Frame frame;
168 void start_new_audio_block(const uint8_t *start);
169 void start_new_frame(const uint8_t *start);
171 void queue_frame(uint16_t format, uint16_t timecode, FrameAllocator::Frame frame, std::deque<QueuedFrame> *q);
172 void dequeue_thread_func();
174 static void usb_thread_func();
175 static void cb_xfr(struct libusb_transfer *xfr);
177 std::string description;
179 FrameAllocator::Frame current_video_frame;
180 FrameAllocator::Frame current_audio_frame;
182 std::mutex queue_lock;
183 std::condition_variable queues_not_empty;
184 std::deque<QueuedFrame> pending_video_frames;
185 std::deque<QueuedFrame> pending_audio_frames;
187 FrameAllocator *video_frame_allocator = nullptr;
188 FrameAllocator *audio_frame_allocator = nullptr;
189 frame_callback_t frame_callback = nullptr;
191 std::thread dequeue_thread;
192 std::atomic<bool> dequeue_thread_should_quit;
193 bool has_dequeue_callbacks = false;
194 std::function<void()> dequeue_init_callback = nullptr;
195 std::function<void()> dequeue_cleanup_callback = nullptr;
197 int current_register = 0;
199 static constexpr int NUM_BMUSB_REGISTERS = 60;
200 uint8_t register_file[NUM_BMUSB_REGISTERS];
203 std::vector<libusb_transfer *> iso_xfrs;
204 int assumed_frame_width = 1280;
207 // Get details for the given video format; returns false if detection was incomplete.
208 // Note: Frame rate is _frame_ rate, not field rate. So 1080i60 gets 30/1, _not_ 60/1.
209 // "second_field_start" is only valid for interlaced modes; it signifies
210 // how many lines from the very top of the frame there are before the second field
211 // starts (so it will always be >= height/2 + extra_lines_top).
212 bool decode_video_format(uint16_t video_format, VideoFormat *decoded_video_format);