The odd one out: its capture is not a C790 on a camera ribbon but M5Stack's own Add-on Display In, which plugs onto a 24-pin flat cable and brings a microSD slot with it. The same IP101 Ethernet on the same pins as the P4-ETH, and 802.3at PoE.
Measured
One viewer, a screen playing video, 2026-09-23 (the 1080p rows 2026-10-08, after the frame gate):
| Codec | Mode | fps | Bitrate |
|---|---|---|---|
| MJPEG | 1080p | 11 | 17-18 Mbit/s |
| MJPEG | 720p | 21-23 | 21-23 Mbit/s |
| H.264 | 1080p | 7 | 0.5-1.2 Mbit/s |
| H.264 | 720p | 17 | 1-1.8 Mbit/s |
From the pointer moved on the target to the browser showing it, at 720p over H.264: about 185 ms (2026-10-10, 0.62.0).
720p is the mode to give this board. The byte reordering its bridge needs costs four times less there, and over a network H.264 at 720p gives 17 fps at a fifteenth of MJPEG's bandwidth. Pick 720p in the target's own display settings: the bridge holds its own EDID, so ESP-KVM cannot offer fewer modes. The console suggests 720p, or MJPEG, when it sees H.264 above 720p on this board.
If it has to be 1080p, give it 30 Hz, not 60. The bridge writes every frame it receives into memory, whether or not it gets encoded, and at 60 Hz that alone takes most of the memory's bandwidth. Since 0.62.0 the firmware lets through only the frames it can use, so the gap is small now: H.264 at 1080p gives 7 fps at 60 Hz and 8 at 30 Hz.
Good to know
- The picture comes out a little flat: the PC sends limited-range RGB to what it thinks is a TV. Setting the graphics driver's HDMI output range to Full fixes half of it; the other half is the bridge's own conversion.
- The microSD slot on the add-on writes at 40 MHz, so recording, screenshots and the dashcam all work.
- The bridge cannot tell whether the source is switched on, so after a long "No signal" the console offers a Reconnect HDMI button with a countdown.
The rev 3.x version, the PoE-P4X, takes the same firmware from an image of its own.
