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;
70 uint16_t id = 0; // For debugging/logging only.
71 unsigned bits_per_sample = 0;
72 unsigned num_channels = 0;
75 typedef std::function<void(uint16_t timecode,
76 FrameAllocator::Frame video_frame, size_t video_offset, VideoFormat video_format,
77 FrameAllocator::Frame audio_frame, size_t audio_offset, AudioFormat audio_format)>
80 class CaptureInterface {
82 virtual ~CaptureInterface() {}
84 // Does not take ownership.
85 virtual void set_video_frame_allocator(FrameAllocator *allocator) = 0;
87 virtual FrameAllocator *get_video_frame_allocator() = 0;
89 // Does not take ownership.
90 virtual void set_audio_frame_allocator(FrameAllocator *allocator) = 0;
92 virtual FrameAllocator *get_audio_frame_allocator() = 0;
94 virtual void set_frame_callback(frame_callback_t callback) = 0;
96 // Needs to be run before configure_card().
97 virtual void set_dequeue_thread_callbacks(std::function<void()> init, std::function<void()> cleanup) = 0;
99 // Only valid after configure_card().
100 virtual std::string get_description() const = 0;
102 virtual void configure_card() = 0;
104 virtual void start_bm_capture() = 0;
106 virtual void stop_dequeue_thread() = 0;
109 // The actual capturing class, representing capture from a single card.
110 class BMUSBCapture : public CaptureInterface {
112 BMUSBCapture(int card_index)
113 : card_index(card_index)
119 // Does not take ownership.
120 void set_video_frame_allocator(FrameAllocator *allocator) override
122 video_frame_allocator = allocator;
125 FrameAllocator *get_video_frame_allocator() override
127 return video_frame_allocator;
130 // Does not take ownership.
131 void set_audio_frame_allocator(FrameAllocator *allocator) override
133 audio_frame_allocator = allocator;
136 FrameAllocator *get_audio_frame_allocator() override
138 return audio_frame_allocator;
141 void set_frame_callback(frame_callback_t callback) override
143 frame_callback = callback;
146 // Needs to be run before configure_card().
147 void set_dequeue_thread_callbacks(std::function<void()> init, std::function<void()> cleanup) override
149 dequeue_init_callback = init;
150 dequeue_cleanup_callback = cleanup;
151 has_dequeue_callbacks = true;
154 // Only valid after configure_card().
155 std::string get_description() const override {
159 void configure_card() override;
160 void start_bm_capture() override;
161 void stop_dequeue_thread() override;
163 // TODO: It's rather messy to have these outside the interface.
164 static void start_bm_thread();
165 static void stop_bm_thread();
171 FrameAllocator::Frame frame;
174 void start_new_audio_block(const uint8_t *start);
175 void start_new_frame(const uint8_t *start);
177 void queue_frame(uint16_t format, uint16_t timecode, FrameAllocator::Frame frame, std::deque<QueuedFrame> *q);
178 void dequeue_thread_func();
180 static void usb_thread_func();
181 static void cb_xfr(struct libusb_transfer *xfr);
183 std::string description;
185 FrameAllocator::Frame current_video_frame;
186 FrameAllocator::Frame current_audio_frame;
188 std::mutex queue_lock;
189 std::condition_variable queues_not_empty;
190 std::deque<QueuedFrame> pending_video_frames;
191 std::deque<QueuedFrame> pending_audio_frames;
193 FrameAllocator *video_frame_allocator = nullptr;
194 FrameAllocator *audio_frame_allocator = nullptr;
195 frame_callback_t frame_callback = nullptr;
197 std::thread dequeue_thread;
198 std::atomic<bool> dequeue_thread_should_quit;
199 bool has_dequeue_callbacks = false;
200 std::function<void()> dequeue_init_callback = nullptr;
201 std::function<void()> dequeue_cleanup_callback = nullptr;
203 int current_register = 0;
205 static constexpr int NUM_BMUSB_REGISTERS = 60;
206 uint8_t register_file[NUM_BMUSB_REGISTERS];
209 std::vector<libusb_transfer *> iso_xfrs;
210 int assumed_frame_width = 1280;
213 // Get details for the given video format; returns false if detection was incomplete.
214 // Note: Frame rate is _frame_ rate, not field rate. So 1080i60 gets 30/1, _not_ 60/1.
215 // "second_field_start" is only valid for interlaced modes; it signifies
216 // how many lines from the very top of the frame there are before the second field
217 // starts (so it will always be >= height/2 + extra_lines_top).
218 bool decode_video_format(uint16_t video_format, VideoFormat *decoded_video_format);