if (is_active) {
card->capture->set_frame_callback(bind(&Mixer::bm_frame, this, card_index, _1, _2, _3, _4, _5, _6, _7));
if (card->frame_allocator == nullptr) {
if (is_active) {
card->capture->set_frame_callback(bind(&Mixer::bm_frame, this, card_index, _1, _2, _3, _4, _5, _6, _7));
if (card->frame_allocator == nullptr) {