USB Capture (UVC)

pMix.studio can receive video from USB Video Class (UVC) capture devices — typically HDMI-to-USB-C adapters that let you capture video from cameras, computers, game consoles, or any HDMI source.

Requirements

• A USB-C UVC capture device (HDMI input, USB-C output)
• Connected directly to the iPad’s USB-C port
• iPad with USB-C (all iPads with Apple Silicon)

Adding a UVC source

1. Connect the UVC capture device to the iPad’s USB-C port
2. Connect your HDMI source to the capture device
3. Tap + on an empty source slot
4. Select UVC
5. Choose the capture device (or it’s selected automatically if only one is connected)

The HDMI video appears in the source slot.

Audio

A USB capture slot is video only. iPad does not hand an app a capture card’s embedded audio through the video device, on any card.

To take the card’s audio, add an Audio Input source and pick the card’s USB input as the device. That gives you an explicit device choice, channel mapping, and a real strip on the mixer — see Audio Input Sources.

Common UVC devices

Most USB-C HDMI capture devices work, including:

• Elgato Cam Link 4K
• Elgato HD60 X
• Generic HDMI-to-USB-C capture cards
• Magewell USB Capture HDMI

Use cases

• HDMI cameras — Connect a traditional camera with HDMI output
• Computer output — Capture a presentation from a laptop
• Game consoles — Capture PlayStation, Xbox, or Switch output
• Hardware sources — Any device with HDMI output

OSC control

A UVC device can be assigned to a slot via OSC:

/streamit/slot/{n}/uvc          # Assign first available UVC device
/streamit/slot/{n}/uvc "Device Name"  # Assign specific device

Control API

A capture card can also be put on a slot without touching the iPad. Run discovery with the uvc backend and GET /inputs/discovered lists each attached card with the resolutions and frame rates it advertises. POST /inputs/quick-add {"kind": "uvc"} puts one on the first empty slot; PUT /inputs/{slotIndex} with "type": "uvc" puts it on a named slot. With one card plugged in that is the whole request; with two, the response names both and asks you to pick a device_id. A requested resolution or frame rate is checked against what the slot would actually open at and refused before anything is created, rather than quietly substituted. An AI assistant reaches the same thing through the inputs_add_uvc and inputs_configure_uvc MCP tools.

The slot carries picture only, as above. The card’s audio is a separate Audio Input source pinned to its USB audio port, which is why one card appears twice in the discovered list. See the REST API.

Multitasking

USB capture keeps running when pMix.studio shares the screen — Split View, Slide Over, and Stage Manager all keep the HDMI feed live. You can take notes or watch chat beside the app without your capture source going dark.

Limitations

• Video only — the card’s audio comes in as a separate Audio Input source
• Only one USB-C port on most iPads — you can only connect one UVC device at a time (unless using a USB hub)
• The capture resolution and frame rate depend on the UVC device’s capabilities
• Some capture devices introduce 1–3 frames of latency