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g2 CFW demos

Two small Bun programs that talk to a pair of Even Realities G2 glasses over Bluetooth and show off the custom firmware built by ../build_cfw.sh:

  • detect-cfw.ts — reads the glasses' settings and reports whether they're running the custom firmware, and which extensions it advertises. Works on stock firmware too (it just reports "no CFW").
  • video-bench.ts — streams a video (as a GIF) to the lens as fast as it acks and benchmarks the achieved framerate / byte count. Streams via the CFW's compressed packed-4bpp keyframe and delta modes.

They depend on g2-kit (a reverse-engineered BLE library for the G2), pulled directly from GitHub — see package.json. Nothing here needs the rest of this repo at runtime; the CFW just needs to already be flashed for the demos to show anything interesting.

Setup

cd demos
bun install

The glasses must be powered on and not connected to the phone (quit the Even app / turn off the phone's Bluetooth) so they advertise for a direct connection. On macOS the first run prompts for Bluetooth permission.

Detect the firmware

bun detect-cfw.ts        # or: bun run detect

On the custom firmware you'll see something like:

firmware: L=2.2.4.34 R=2.2.4.34
CFW detected: EVENCFW/6 img576 img640 imgz rle wakelease directfb fbguard
  contract v6, features: img576, img640, imgz, rle, wakelease, directfb, fbguard
  img576=yes img640=yes imgz=yes rle=yes directfb=yes fbguard=yes

On stock firmware it prints no CFW capability field.

Video streaming benchmark

video-bench.ts takes a GIF and streams its frames. Make one from any video with ffmpeg (grayscale, sized to the lens):

ffmpeg -i input.mp4 -vf "fps=30,scale=288:144:flags=area,format=gray" demo.gif
bun video-bench.ts demo.gif        # or: bun run bench demo.gif

It decodes/rescales/compresses every frame up front, then streams them in order, pacing on the per-fragment acks, and prints framerate + bytes at the end.

Useful environment variables:

Var Default Meaning
G2_IMG_W / G2_IMG_H 640 / 480 target size (CFW modes are fixed at 640×480; lz4 defaults to 288×144)
G2_IMG_THRESHOLD -1 >=0 = 1-bit threshold; -1 = grayscale
G2_MODE delta delta = mode-6 keyframe plus mode-3 bounding-box updates; raw4 = mode-6 full frames; lz4 = stock compressed BMP. CFW modes RLE pixels before deflate.
G2_KEYFRAME_INTERVAL 0 in delta mode, force a full frame every N
G2_FRAME_STRIDE 1 use every Nth source frame
G2_MAX_FRAMES 0 cap frame count (0 = all)
G2_WINDOW 2 image messages in flight at once (1 = serial)
G2_DRY_RUN — 1 = decode/compress/report only, don't connect

Sweep G2_WINDOW (e.g. 1, 2, 4) to see how much the ack round-trip is costing — higher windows overlap the next frame's BLE transfer with the current frame's on-device processing.

Requires the custom firmware

video-bench.ts uses display modes that only exist in the CFW; against stock firmware it won't render. Build and flash the firmware first (see the top-level README), then confirm with detect-cfw.ts.