6 #include <condition_variable>
15 struct libusb_transfer;
17 // An interface for frame allocators; if you do not specify one
18 // (using set_video_frame_allocator), a default one that pre-allocates
19 // a freelist of eight frames using new[] will be used. Specifying
20 // your own can be useful if you have special demands for where you want the
21 // frame to end up and don't want to spend the extra copy to get it there, for
22 // instance GPU memory.
23 class FrameAllocator {
26 uint8_t *data = nullptr;
27 uint8_t *data2 = nullptr; // Only if interleaved == true.
28 size_t len = 0; // Number of bytes we actually have.
29 size_t size = 0; // Number of bytes we have room for.
31 void *userdata = nullptr;
32 FrameAllocator *owner = nullptr;
34 // If set to true, every other byte will go to data and to data2.
35 // If so, <len> and <size> are still about the number of total bytes
36 // so if size == 1024, there's 512 bytes in data and 512 in data2.
37 bool interleaved = false;
40 virtual ~FrameAllocator();
42 // Request a video frame. Note that this is called from the
43 // USB thread, which runs with realtime priority and is
44 // very sensitive to delays. Thus, you should not do anything
45 // here that might sleep, including calling malloc().
46 // (Taking a mutex is borderline.)
48 // The Frame object will be given to the frame callback,
49 // which is responsible for releasing the video frame back
50 // once it is usable for new frames (ie., it will no longer
51 // be read from). You can use the "userdata" pointer for
52 // whatever you want to identify this frame if you need to.
54 // Returning a Frame with data==nullptr is allowed;
55 // if so, the frame in progress will be dropped.
56 virtual Frame alloc_frame() = 0;
58 virtual void release_frame(Frame frame) = 0;
61 // Audio is more important than video, and also much cheaper.
62 // By having many more audio frames available, hopefully if something
63 // starts to drop, we'll have CPU load go down (from not having to
64 // process as much video) before we have to drop audio.
65 #define NUM_QUEUED_VIDEO_FRAMES 16
66 #define NUM_QUEUED_AUDIO_FRAMES 64
68 class MallocFrameAllocator : public FrameAllocator {
70 MallocFrameAllocator(size_t frame_size, size_t num_queued_frames);
71 Frame alloc_frame() override;
72 void release_frame(Frame frame) override;
77 std::mutex freelist_mutex;
78 std::stack<std::unique_ptr<uint8_t[]>> freelist; // All of size <frame_size>.
82 uint16_t id = 0; // For debugging/logging only.
83 unsigned width = 0, height = 0, second_field_start = 0;
84 unsigned extra_lines_top = 0, extra_lines_bottom = 0;
85 unsigned frame_rate_nom = 0, frame_rate_den = 0;
86 bool interlaced = false;
87 bool has_signal = false;
91 uint16_t id = 0; // For debugging/logging only.
92 unsigned bits_per_sample = 0;
93 unsigned num_channels = 0;
96 typedef std::function<void(uint16_t timecode,
97 FrameAllocator::Frame video_frame, size_t video_offset, VideoFormat video_format,
98 FrameAllocator::Frame audio_frame, size_t audio_offset, AudioFormat audio_format)>
101 class CaptureInterface {
103 virtual ~CaptureInterface() {}
105 // Does not take ownership.
106 virtual void set_video_frame_allocator(FrameAllocator *allocator) = 0;
108 virtual FrameAllocator *get_video_frame_allocator() = 0;
110 // Does not take ownership.
111 virtual void set_audio_frame_allocator(FrameAllocator *allocator) = 0;
113 virtual FrameAllocator *get_audio_frame_allocator() = 0;
115 virtual void set_frame_callback(frame_callback_t callback) = 0;
117 // Needs to be run before configure_card().
118 virtual void set_dequeue_thread_callbacks(std::function<void()> init, std::function<void()> cleanup) = 0;
120 // Only valid after configure_card().
121 virtual std::string get_description() const = 0;
123 virtual void configure_card() = 0;
125 virtual void start_bm_capture() = 0;
127 virtual void stop_dequeue_thread() = 0;
130 // The actual capturing class, representing capture from a single card.
131 class BMUSBCapture : public CaptureInterface {
133 BMUSBCapture(int card_index)
134 : card_index(card_index)
140 // Does not take ownership.
141 void set_video_frame_allocator(FrameAllocator *allocator) override
143 video_frame_allocator = allocator;
146 FrameAllocator *get_video_frame_allocator() override
148 return video_frame_allocator;
151 // Does not take ownership.
152 void set_audio_frame_allocator(FrameAllocator *allocator) override
154 audio_frame_allocator = allocator;
157 FrameAllocator *get_audio_frame_allocator() override
159 return audio_frame_allocator;
162 void set_frame_callback(frame_callback_t callback) override
164 frame_callback = callback;
167 // Needs to be run before configure_card().
168 void set_dequeue_thread_callbacks(std::function<void()> init, std::function<void()> cleanup) override
170 dequeue_init_callback = init;
171 dequeue_cleanup_callback = cleanup;
172 has_dequeue_callbacks = true;
175 // Only valid after configure_card().
176 std::string get_description() const override {
180 void configure_card() override;
181 void start_bm_capture() override;
182 void stop_dequeue_thread() override;
184 // TODO: It's rather messy to have these outside the interface.
185 static void start_bm_thread();
186 static void stop_bm_thread();
192 FrameAllocator::Frame frame;
195 void start_new_audio_block(const uint8_t *start);
196 void start_new_frame(const uint8_t *start);
198 void queue_frame(uint16_t format, uint16_t timecode, FrameAllocator::Frame frame, std::deque<QueuedFrame> *q);
199 void dequeue_thread_func();
201 static void usb_thread_func();
202 static void cb_xfr(struct libusb_transfer *xfr);
204 std::string description;
206 FrameAllocator::Frame current_video_frame;
207 FrameAllocator::Frame current_audio_frame;
209 std::mutex queue_lock;
210 std::condition_variable queues_not_empty;
211 std::deque<QueuedFrame> pending_video_frames;
212 std::deque<QueuedFrame> pending_audio_frames;
214 FrameAllocator *video_frame_allocator = nullptr;
215 FrameAllocator *audio_frame_allocator = nullptr;
216 frame_callback_t frame_callback = nullptr;
218 std::thread dequeue_thread;
219 std::atomic<bool> dequeue_thread_should_quit;
220 bool has_dequeue_callbacks = false;
221 std::function<void()> dequeue_init_callback = nullptr;
222 std::function<void()> dequeue_cleanup_callback = nullptr;
224 int current_register = 0;
226 static constexpr int NUM_BMUSB_REGISTERS = 60;
227 uint8_t register_file[NUM_BMUSB_REGISTERS];
230 std::vector<libusb_transfer *> iso_xfrs;
231 int assumed_frame_width = 1280;
234 // Get details for the given video format; returns false if detection was incomplete.
235 // Note: Frame rate is _frame_ rate, not field rate. So 1080i60 gets 30/1, _not_ 60/1.
236 // "second_field_start" is only valid for interlaced modes; it signifies
237 // how many lines from the very top of the frame there are before the second field
238 // starts (so it will always be >= height/2 + extra_lines_top).
239 bool decode_video_format(uint16_t video_format, VideoFormat *decoded_video_format);