+// Audio is more important than video, and also much cheaper.
+// By having many more audio frames available, hopefully if something
+// starts to drop, we'll have CPU load go down (from not having to
+// process as much video) before we have to drop audio.
+#define NUM_QUEUED_VIDEO_FRAMES 16
+#define NUM_QUEUED_AUDIO_FRAMES 64
+
+class MallocFrameAllocator : public FrameAllocator {
+public:
+ MallocFrameAllocator(size_t frame_size, size_t num_queued_frames);
+ Frame alloc_frame() override;
+ void release_frame(Frame frame) override;
+
+private:
+ size_t frame_size;
+
+ std::mutex freelist_mutex;
+ std::stack<std::unique_ptr<uint8_t[]>> freelist; // All of size <frame_size>.
+};
+
+// Represents an input mode you can tune a card to.
+struct VideoMode {
+ std::string name;
+ bool autodetect = false; // If true, all the remaining fields are irrelevant.
+ unsigned width = 0, height = 0;
+ unsigned frame_rate_num = 0, frame_rate_den = 0;
+ bool interlaced = false;
+};
+
+// Represents the format of an actual frame coming in.
+struct VideoFormat {
+ uint16_t id = 0; // For debugging/logging only.
+ unsigned width = 0, height = 0, second_field_start = 0;
+ unsigned extra_lines_top = 0, extra_lines_bottom = 0;
+ unsigned frame_rate_nom = 0, frame_rate_den = 0;
+ bool interlaced = false;
+ bool has_signal = false;
+};
+
+struct AudioFormat {
+ uint16_t id = 0; // For debugging/logging only.
+ unsigned bits_per_sample = 0;
+ unsigned num_channels = 0;
+};
+