gistfile1.txt

int main() {
  ... declare vars ...
  av_register_all();
  avdevice_register_all();
  fmt = av-find-input-format("avfoundation");
  ctx = avformat-alloc-context());
  ctx->iformat = fmt;
  printf("%d\n", avdevice_list_devices(ctx, list));
  return 0;
}