tomato/src/content/sdl_video_frame_stream2.cpp

82 lines
2.1 KiB
C++

#include "./sdl_video_frame_stream2.hpp"
#include <chrono>
#include <cstdint>
#include <iostream>
#include <memory>
#include <thread>
SDLVideoCameraContent::SDLVideoCameraContent(void) {
int devcount = 0;
SDL_CameraDeviceID *devices = SDL_GetCameraDevices(&devcount);
if (devices == nullptr || devcount < 1) {
throw int(1); // TODO: proper exception?
}
std::cout << "### found cameras:\n";
for (int i = 0; i < devcount; i++) {
const SDL_CameraDeviceID device = devices[i];
char *name = SDL_GetCameraDeviceName(device);
std::cout << " - Camera #" << i << ": " << name << "\n";
SDL_free(name);
}
_camera = {
SDL_OpenCameraDevice(devices[0], nullptr),
&SDL_CloseCamera
};
if (!static_cast<bool>(_camera)) {
throw int(2);
}
SDL_CameraSpec spec;
float interval {0.1f};
if (SDL_GetCameraFormat(_camera.get(), &spec) < 0) {
// meh
} else {
// interval
interval = float(spec.interval_numerator)/float(spec.interval_denominator);
std::cout << "camera interval: " << interval*1000 << "ms\n";
}
_thread = std::thread([this, interval](void) {
while (!_thread_should_quit) {
Uint64 timestampNS = 0;
SDL_Surface* sdl_frame_next = SDL_AcquireCameraFrame(_camera.get(), &timestampNS);
// no new frame yet, or error
if (sdl_frame_next == nullptr) {
// only sleep 1/10, we expected a frame
std::this_thread::sleep_for(std::chrono::milliseconds(int64_t(interval*1000 / 10)));
continue;
}
SDLVideoFrame new_frame {
timestampNS,
sdl_frame_next
};
bool someone_listening = pushValue(new_frame);
SDL_ReleaseCameraFrame(_camera.get(), sdl_frame_next);
if (someone_listening) {
// TODO: maybe double the freq?
std::this_thread::sleep_for(std::chrono::milliseconds(int64_t(interval*1000)));
} else {
// we just sleep 4x as long, bc no one is listening
std::this_thread::sleep_for(std::chrono::milliseconds(int64_t(interval*1000*4)));
}
}
});
}
SDLVideoCameraContent::~SDLVideoCameraContent(void) {
_thread_should_quit = true;
_thread.join();
// TODO: what to do if readers are still present?
}