Function feed_real_capture 

fn feed_real_capture(
    encoder: Arc<Mutex<Option<Box<dyn VideoEncoder>>>>,
    cancel: Arc<AtomicBool>,
    camera_slot: FrameSlot,
    screen_slot: FrameSlot,
    audio_mixer: SharedAudioMixer,
    width: u32,
    height: u32,
    framerate: u32,
    screen_dims: StreamDimensions,
    cam_dims: StreamDimensions,
)

Real-capture feed loop (M-PIX.6) — pulls composed frames from crate::recording_compose::RecordingCompose + mixed audio from the shared SharedAudioMixer until cancel fires.

Built inside the worker thread so wisp’s wgpu Application doesn’t cross thread boundaries. If the compose pump fails to init (no GPU adapter, etc.) the thread logs + exits cleanly — the encoder still finalizes whatever audio happened to arrive.