Date: 2026-03-31 System: MacBook Pro, Apple M3 Pro, macOS 26.4 (Tahoe, build 25E246) Monitor: Philips PHL34E1C5600 (34" UWQHD, 3440x1440@60Hz) Connection: USB-C
Can you check why my Philips external screen webcam is not working
Ran system_profiler SPCameraDataType — only FaceTime HD Camera and OBS Virtual Camera detected. No Philips webcam.
Ran system_profiler SPDisplaysDataType — confirmed PHL34E1C5600 connected, 3440x1440.
Inspected ioreg USB device tree — the Philips monitor presents as a USB composite device with 4 interfaces, all over USB 2.0 (480 Mbps):
| Interface | Class | Description |
|---|---|---|
| @0 | 1 (Audio) | Audio Control |
| @1 | 1 (Audio) | Audio Streaming |
| @2 | 1 (Audio) | Audio Streaming |
| @3 | 3 (HID) | Human Interface Device |
No USB Video Class (class 14) interface — the webcam isn't being exposed. UVCAssistant logs confirmed zero UVC devices registered.
Initial hypothesis: monitor not connected via USB-C (display metadata showed DP connection, Thunderbolt ports showed "No device connected"). Suggested connecting via USB-C.
I'm using USB-C
Re-examined. The Philips device was at UsbLinkSpeed = 480000000 (USB 2.0) despite USB-C. No USB 3.0 hub from the monitor was visible. All devices routed through a "USB2.0 Hub".
Revised hypothesis: the USB-C cable only supports USB 2.0 data. Webcam needs USB 3.0 bandwidth. Suggested replacing cable with a USB 3.2 Gen 1+ cable.
No, it worked before with this cable
Since same cable worked before, checked for connection degradation. Inspected AppleTypeCPhy lane allocation:
Port @2 (monitor):
Lane 0: Transport = "DisplayPort" (HBR3, 8.1 Gbps/lane)
Lane 1: Transport = "DisplayPort" (HBR3, 8.1 Gbps/lane)
USB2: on
USB3: NONE
Both SuperSpeed lanes allocated to DisplayPort — no lanes left for USB 3.0. The webcam can't enumerate over USB 2.0.
3440x1440@60Hz only needs ~8 Gbps — 2 DP lanes at HBR3 would suffice. But monitor was requesting all 4 lanes. Suggested lowering refresh rate to 60Hz to force 2-lane DP.
It's 60Hz already
Confirmed 60Hz via system_profiler SPDisplaysDataType. Even at 60Hz, both lanes were still on DisplayPort. This is a monitor-side negotiation issue.
Identified the monitor OSD setting as the likely cause: Philips 34E1C5600 has a "USB-C Connection" setting with "High Resolution" (4-lane DP, USB 2.0 only) vs "High Data Speed" (2-lane DP + USB 3.0). Suggested checking the OSD.
I have High Resolution and High Data Speed. It was High Resolution. I switched to High Data Speed.
Verified lane allocation changed:
Port @2 (monitor) — AFTER OSD change:
Lane 0: Transport = "USB3" (on)
Lane 1: Transport = "DisplayPort" (on)
USB2: on
USB 3.0 lane now available. But the Philips USB device still showed 480 Mbps — hadn't re-enumerated. Suggested unplugging and re-plugging the cable.
I unplugged and re-plugged
Checked again — USB device still at 480 Mbps, no camera. But new USB 3.0 hubs appeared from the monitor at 5 Gbps:
USB3.0 Hub@00200000 (UsbLinkSpeed = 5000000000)
└─ USB3.0 Hub@00240000 (5 Gbps)
The USB 3.0 hubs were now enumerated but empty — the webcam hadn't appeared on them yet. Also saw a "USB Billboard Device" indicating incomplete negotiation.
Suggested a full monitor power cycle (power button off, wait 10 seconds, power on) to get the webcam to initialize on the USB 3.0 bus.
The monitor's OSD setting "USB-C Connection" was set to "High Resolution" (4-lane DisplayPort, USB 2.0 only). This consumed both SuperSpeed lanes for DisplayPort, leaving no bandwidth for USB 3.0. The webcam (UVC class 14) requires USB 3.0 to enumerate and was not exposed over USB 2.0.
- Changed monitor OSD: "High Resolution" → "High Data Speed"
- Unplugged and re-plugged USB-C cable
- USB 3.0 hubs appeared at 5 Gbps
- Full monitor power cycle likely needed for webcam to initialize
Pending — awaiting monitor power cycle to confirm webcam appears.