Working snapshot before the OpenVINO MetricGAN GPU spike: thread-capped SpeechBrain DelaySum+MetricGAN on CPU, hop 200 ms, video hold for A/V sync, Arc VAAPI H.264, headless kmssink wall. 32 tests passing. Do not treat this as a GPU audio path.
nobuffer, low_delay, and a small thread_queue_size on the camera mic capture process.