Hands: --record-hz, and the hand recorder's design (hands/rec/DESIGN.md)

ft-hands --record-hz N records at most N frame sets a second, for the hand recorder (10).
DESIGN.md lays out the recorder: the headset panel, the session runner and its script,
the files, review and export, consent.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

hands/README.md

@@ -109,7 +109,7 @@ Options:
 - `--nice N`: niceness. Default 5, so the VR stack wins contested CPUs.
 - `--no-publish`: don't write the hands and gestures files.
 - `--no-gestures`: hands for the cutouts only. No pinch or grip detection, so nothing reaches the pointer and a closing hand doesn't raise the rate to 30 Hz. The gestures file is removed at start. `ft-cutouts` runs it this way.
-- `--record DIR`, `--record-for S`: save every frame set for S seconds (default 120) to `DIR/sets.bin`. That's about 80 MB/s. Sending the tracker SIGUSR1 (`pkill -USR1 -x ft-hands`) starts a recording in `~/.local/share/frametop/hands/rec-<time>` without a restart. Recordings are images of your hands and room: they stay on the headset unless you move them.
+- `--record DIR`, `--record-for S`, `--record-hz N`: save every frame set for S seconds (default 120) to `DIR/sets.bin`, or at most N sets a second with `--record-hz` (the hand recorder uses 10). Every set is about 80 MB/s. Sending the tracker SIGUSR1 (`pkill -USR1 -x ft-hands`) starts a recording in `~/.local/share/frametop/hands/rec-<time>` without a restart. Recordings are images of your hands and room: they stay on the headset unless you move them.
 - `--record-only`: record without tracking or publishing, so it can run beside the live tracker. Give it `--record DIR`, since SIGUSR1 would reach both trackers. With `ft-camd --with-dark`, recordings also hold each camera's newest dark frame as `<name>_dk`, which doubles the rate. With `--with-color`, each colour camera's newest frame is saved with every set, as `color_video<N>`, which adds about 70 MB/s. Run the recorder at normal I/O priority: idle I/O priority stalled a 165 MB/s recording.
 - `--keep-presence P`: the landmark presence a tracked view needs to stay tracked. New views always need 0.5. Default 0.5. Lowering it to 0.2 barely helped in the bright recording, because lost hands drop to near-zero presence.
 - `--ring PATH`: read frames from another ring, such as `ft-ringplay`'s.

hands/rec/DESIGN.md

@@ -0,0 +1,203 @@
+# Hand recorder: design (Phase 1 of the hands plan)
+
+The hand recorder guides a person through recording their hands with the headset's cameras. It saves the recordings as files, lets them review and delete anything, then exports a package to contribute to the open hand dataset. Recordings never leave the headset unless the person uploads them.
+
+The plan this belongs to is `~/Desktop/Projects/frame-hands/notes/hands-plan.md` (on the maintainer's Frame). In short, the dataset trains a small hand model for Frametop's hand cutouts.
+
+## Parts
+
+| Part | What it does |
+|---|---|
+| `hands/rec/panel/ft-handpanel.cpp` (C++, dev container) | The headset panel: a SteamVR overlay fixed to the head that shows the prompts. It also places the "touch the dot" target in the room and logs head and controller poses. Driven over `@ft_handpanel`. |
+| `hands/rec/session.py` (Python, no Qt) | The session runner. It reads `script.json`, starts and stops the recordings, and drives the panel. It reads the live hands file for feedback and writes each take's files. It also runs from the command line (`--dry-run`) for testing. |
+| `hands/rec/script.json` | The guided script: sections, prompts, timings. |
+| `hands/rec/takes.py` (Python, no Qt) | Reads sessions and takes from disk: frame sets for review, deleted ranges, export (compress, strip, manifest, checksums). |
+| `hands/rec/ft_handrec.py` + `main.qml` (PySide6 + Kirigami, dev container) | The desktop window: consent, the before-you-start checklist, the session controls, review, export and upload instructions. |
+| `hands/rec/ft-handrec` | The host launcher, like `input-settings/ft-input-settings`. |
+| `hands/rec/build.sh` | Builds `ft-handpanel` into `hands/rec/build/`, like `gaze/build.sh`. |
+| `hands/rec/CONSENT.md`, `hands/rec/UPLOAD.md` | The texts the window shows. |
+| ft-hands `--record-hz N` (done) | Records at most N frame sets a second. The recorder uses 10. |
+
+Every part runs in the dev container, as ft-hands and Input Settings do. The host Python isn't used: it lacks PySide6 and zstd. `setup/dev-container.sh` gains `zstd`.
+
+## Processes during a session
+
+- **ft-camd** publishes the camera ring. If it isn't running, the session starts it as the transient user unit `frametop-handrec-camd.service`, the way `hands/ft-cutouts` starts `frametop-cutouts-camd.service` (needs `hands/build/ft-camd` with capabilities: `hands/run.sh caps`). An ft-camd already running from ft-cutouts or ft-handsctl is used as it is.
+- **A tracking ft-hands** gives feedback through the hands file: which hands are seen, the palm's distance, the index tip. If none is running, the session starts `ft-hands --no-gestures --status 0` (unit `frametop-handrec-hands.service`). An ft-hands already running is used as it is.
+- **A recording ft-hands** runs once per take: `ft-hands --record-only --record TAKE_DIR --record-for SECONDS --record-hz 10 --status 0`. It runs as a plain child process of the session, ended with SIGTERM if the take stops early. SIGTERM ends ft-hands' loop, and `Recorder` writes out its queue when it's destroyed.
+- **ft-handpanel** runs as a child process with `--watch-stdin`. It shows the panel and logs poses during each take.
+
+Test hooks:
+- `--ring PATH` goes to both ft-hands (`ft-ringplay` publishes a recording there, so the whole flow runs without the headset).
+- `--no-start` uses only what's already running.
+- `--dry-run` runs no processes and only prints the panel commands, with timing sped up by `--speed X`.
+
+## Files
+
+```
+~/.local/share/frametop/hands/contrib/
+  profile.json                  consent and contributor id (below)
+  sessions/<YYYYMMDD-HHMMSS>/
+    session.json                the session: checklist answers, lighting, versions, takes
+    calibration.json            /persist/xrservice.json with identifying fields removed (below)
+    takes/<NN>-<section>/
+      sets.bin                  ft-hands' recording (FHSET01, hands/track/record.h), 10 sets/s
+      prompts.jsonl             what the person was asked to do, when (below)
+      poses.jsonl               head and controller poses from ft-handpanel (below)
+      take.json                 {"section", "title", "started_ns", "ended_ns", "status": "complete"|"stopped"|"skipped",
+                                 "deleted": [[from_ns, to_ns], ...], "notes": ""}
+  exports/<session>/            what export writes (below)
+```
+
+All `_ns` times are CLOCK_MONOTONIC nanoseconds, the clock of `dqbuf_ns` in sets.bin and of `capture_ns` in the hands file. sets.bin's `capture_ns` is the camera clock (CLOCK_MONOTONIC_RAW).
+
+### profile.json
+
+```json
+{"schema": 1, "contributor": "<random uuid4>", "consent": {"version": "2026-10-02", "accepted": "<ISO time>", "adult": true},
+ "optional": {"handedness": "right|left|both|", "notes": ""}}
+```
+
+No name, email, or account. The contributor id is random, so several sessions from one person can be held out together in evaluation. Withdrawal also goes by that id.
+
+### session.json
+
+```json
+{"schema": 1, "tool": "ft-handrec <git describe>", "started": "<ISO>", "contributor": "<uuid>",
+ "lighting": {"chosen": "dim|room|daylight", "ring": {"<cam>": {"mean": 0.0, "dark_mean": 0.0}}},
+ "checklist": {"objects": ["pencil", "phone", "cup", "keyboard", "mouse", "gamepad", "small"], "own_objects": ["..."],
+               "controllers": "straps|none", "sleeves": "short|long|", "rings": false, "watch": false, "notes": ""},
+ "device": {"steamos": "<VERSION_ID from /etc/os-release>", "steamvr": "<version if known>", "cameras": [{"name", "width", "height"}]},
+ "takes": ["01-hand-size", "..."]}
+```
+
+### calibration.json
+
+This is a copy of `/persist/xrservice.json` (`/run/host/persist/` in the container). Keep the cameras' intrinsics and extrinsics, and drop anything that identifies the unit: keys containing `serial`, `sn`, `uuid`, `mac` or `id`, or values that look like serial numbers. List what was removed in `session.json` (`"calibration_removed": [...]`), so a reviewer can check it.
+
+### prompts.jsonl
+
+One JSON object per line:
+
+```json
+{"t": 123, "event": "take", "section": "static-poses", "take": "03-static-poses"}
+{"t": 123, "event": "prompt", "id": "static-poses/fist/left/near", "text": "...", "hands": "left|right|both|none",
+ "pose": "fist", "distance": "near|mid|far|", "position": "centre|left|right|up|down|", "object": "", "controller": false}
+{"t": 123, "event": "target", "id": "touch/3", "head": [x, y, z], "room": [x, y, z], "state": "show|hold|done|timeout"}
+{"t": 123, "event": "bar", "target": 0.0}
+{"t": 123, "event": "feedback", "left": true, "right": false, "palm_m": [0.0, 0.0]}
+{"t": 123, "event": "pause"}
+{"t": 123, "event": "resume"}
+{"t": 123, "event": "end", "status": "complete|stopped|skipped"}
+```
+
+`feedback` is written about twice a second. It's the live tracker's view, kept for later checks; it's not a label.
+
+### poses.jsonl
+
+ft-handpanel writes one line per sample, 250 a second, from `GetDeviceToAbsoluteTrackingPose(TrackingUniverseStanding, 0)`:
+
+```json
+{"t": 123, "hmd": {"m": [12 floats, row-major 3x4], "r": 200, "ok": true},
+ "left": {"m": [...], "r": 200, "ok": true}, "right": null}
+```
+
+`r` is `ETrackingResult` (200 = Running_OK, 201 = Running_OutOfRange, and so on). `left` and `right` are the devices holding those controller roles, or null. No device serials are logged.
+
+## The panel (`ft-handpanel`)
+
+- **Placement.** A SteamVR overlay fixed to the head, like `gaze/panel/ft-gazepanel.cpp`: key `frametop.handpanel`, sort order 250. It sits 1.2 m ahead, centred 12 degrees above straight ahead, so the hands stay clear below it. It's 36 degrees wide, 4:3, 1024x768 pixels, dim and see-through. It's drawn on the CPU with stb_truetype into three shared DMA-BUFs SteamVR imports once, as ft-gazepanel does, and is drawn again only when something changes.
+- **Socket.** Abstract unix datagram `@ft_handpanel` (`--socket NAME`). A sender with an address gets `ok ...` or `error ...`.
+- **Options:** `--watch-stdin` (quit when stdin closes), `--socket NAME`, `--distance M`, `--no-vr`. `--no-vr` makes no SteamVR connection and prints each picture's text to stdout: for testing without a headset.
+
+Commands (UTF-8; `|` starts a new line in text):
+
+| Command | Effect |
+|---|---|
+| `show` / `hide` | The panel. A "show" makes it visible with its first picture. |
+| `title <text>` | Big line at the top. |
+| `step <text>` | Small line at the top right, e.g. `Section 3 of 11`. |
+| `text <text>` | The instruction, large, wrapped to the panel's width, centred. |
+| `note <text>` | An orange line under the instruction: a warning ("I can't see your left hand"). Empty clears it. |
+| `countdown <0..1>` / `countdown off` | A thin bar along the bottom: the share of this prompt's time left. |
+| `hands <left> <right>` | Two chips, "Left hand" and "Right hand", each `seen` (green), `lost` (orange) or `off` (hidden). |
+| `bar <target 0..1> <current 0..1 or -1> [near label] [far label]` / `bar off` | The near/far bar for the push out and back: a horizontal track with a target marker and the hand's current position. |
+| `paused on` / `paused off` | A "Paused" overlay over the picture. |
+| `target <x> <y> <z> [show\|hold <0..1>\|done]` / `target off` | The touch target: a small sphere-like dot about 2 cm across, in its own overlay (`frametop.handpanel.target`). The point is in the head frame (metres, +x right, +y up, -z forward). The first `target` with a new point places it in the room with the current HMD pose, and it stays there. Later commands with the same point change only the state. `hold` draws a filling ring, `done` turns it green. Reply: `ok <room x> <room y> <room z>`. |
+| `poses start <path>` / `poses stop` | Log poses to the path (appending, `poses.jsonl` format above) from a thread at 250 Hz, until stopped. |
+| `devices` | Reply: `ok hmd <r> left <r or -> right <r or ->`, the current `ETrackingResult` values (`-` for no device in that role). |
+| `head` | Reply: `ok <12 floats>`, the current HMD pose (standing universe). |
+| `ping` | `ok shown` or `ok hidden`. |
+
+It quits on SteamVR's quit event, as ft-gazepanel does.
+
+## The script (`script.json`)
+
+```json
+{"version": 1,
+ "sections": [
+   {"id": "hand-size", "title": "Hand size", "requires": [], "intro": "text shown for 4 s before the first prompt",
+    "prompts": [{"text": "...", "seconds": 8, "hands": "both", "pose": "flat", "distance": "near"}]},
+   {"id": "objects", "title": "Things you hold", "requires": ["objects"], "for_each": "object",
+    "prompts": [{"text": "Pick up the {object} and use it the way you normally would.", "seconds": 15, "hands": "both", "object": "{object}"}]},
+   {"id": "touch", "title": "Touch the dot", "kind": "targets", "hold_s": 1.0, "timeout_s": 8,
+    "targets": [[0.0, -0.15, -0.40], ...], "text": "Touch the dot with your index fingertip and hold still."},
+   {"id": "controller-push", "title": "Depth with controllers", "requires": ["controllers"], "kind": "bar",
+    "intro": "...", "heights": ["chest", "desk", "eye", "left", "right"], "reps": 5, "period_s": 6, "near_m": 0.2, "far_m": 0.6}
+ ]}
+```
+
+- `requires`: `objects` (at least one object ticked), `controllers` (straps ticked). A section whose requirements aren't met is skipped and logged.
+- `kind`:
+  - `prompts` (the default): each prompt shows for its `seconds` with a countdown.
+  - `targets`: each target shows until the live index tip is within 3 cm of it for `hold_s`, or `timeout_s` passes.
+  - `bar`: the target marker sweeps near to far and back, `reps` times per height, at `period_s` per sweep. The current marker follows the live palm distance.
+- Each section is one take, one recording. Prompts within it are marked in `prompts.jsonl`.
+
+The sections, in this order (see the plan):
+1. hand size
+2. static poses (both hands, then each hand: open, fist, point, pinch, OK, thumbs up, spread, claw, counting 1-5, at near, mid and far, and centre, left, right, up, down)
+3. wrist rotations
+4. gestures (pinch taps, pinch-drag, grabs, hands crossing and overlapping, hands near the face, hands at screen distance)
+5. desk work (typing, mouse)
+6. objects (one prompt per ticked object, own objects included)
+7. touch the dot
+8. controller depth, straps (push out and back at 3 heights and to each side, wrist turns, open and close)
+9. bridge (one controller on, the bare fingertip touches the marked point on it at near, mid and far, then swap; then a controller on the desk, touched from several angles)
+10. bare repeat of section 8, controllers off
+11. no hands (10 s)
+
+Before section 8: "Put on both controllers and tighten the straps". Before section 10: "Take the controllers off and put them out of view".
+
+### Feedback while recording
+
+- **Hands seen:** from the hands file. A hand counts as seen if its flags match the side and the file is fresh (publish within 0.3 s). Prompts with `hands` set show the `hands` chips. If an asked-for hand is lost for more than 1.5 s, the note says "I can't see your left hand: bring it into view".
+- **Controller tracking:** in sections 8 and 9, `devices` is polled once a second. A result other than 200 for more than 1 s says "The left controller lost tracking: turn your palm slightly toward you". Each such stretch goes into `prompts.jsonl` as `feedback` with `"controller": {...}`.
+- **Lighting check at session start:** the mean of every mono camera's `mean` and `dark_mean` from the ring (`hands/tools/ring.py` layout; struct only, no numpy). It's compared with the person's earlier sessions. If the chosen lighting matches an earlier round's within 15%, the window says so before starting.
+
+### Controls
+
+- The window has Start, Pause/Resume, Skip section and Stop. Space pauses and Esc stops while the window has focus.
+- The panel's text says what to do: "Pause: Space in the Hand recorder window".
+- A pause stops the take's recording and starts it again on resume as the next part of the same take (`sets.bin` is appended to as a second recording file `sets-2.bin`, and so on). takes.py reads all parts in order.
+
+## Review and export (`takes.py`, the window)
+
+- **Review.** Each session lists its takes: title, duration, status, a thumbnail (the first set's `slam_left`). A viewer shows one frame set (all cameras side by side, 8-bit grey) at a time with a slider. It can mark a range and delete it. Deleted ranges go into `take.json`, and export leaves them out; the files keep everything until export. A whole take or session can be deleted (files removed, after a confirmation).
+- **Export.** It writes `exports/<session>/`:
+  - `manifest.json`: profile fields except `optional.notes` unless kept, session.json, takes, schema, tool version, the consent version.
+  - `calibration.json`.
+  - Per take: `prompts.jsonl`, `poses.jsonl`, `take.json`, and `sets.bin.zst` (sets in deleted ranges removed, then zstd -10 with 2 threads).
+  - `SHA256SUMS`.
+
+  Compression runs at nice 19. Before starting, the window warns if the headset is worn: `/sys/bus/iio/devices/iio:device2/in_proximity_raw` over 20, if readable. CPU work while in VR causes stutter.
+- **Upload.** The Upload page shows `UPLOAD.md` with the export's path and size filled in, plus the copyable command.
+
+## Licensing and consent (texts in `CONSENT.md`)
+
+- The dataset is CC BY-NC 4.0.
+- Contributors also grant the maintainer (DeeJanuz) a broad, non-exclusive license to their contribution.
+- Contributors confirm they're 18 or older.
+- The text explains what's recorded and that nothing uploads automatically, how review works, how to withdraw (by contributor id), and that a withdrawal is purged from the repo's history.
+- The texts need a legal review before the dataset launches. Until then they carry a "draft" banner, and the Upload page says contributions aren't open yet.
+- The dataset repo: `HF_DATASET` in `ft_handrec.py`, a placeholder (`DeeJanuz/frametop-hands`) until the maintainer decides.

hands/track/main.cpp

@@ -181,7 +181,7 @@ int main(int argc, char **argv) {
     PinchParams pinch_params;
     GripParams grip_params;
     bool gesture_log = false;   // what the pinch and grip detectors measure, 10 times a second
-    double record_for = 120;
+    double record_for = 120, record_hz = 0;   // record_hz: at most this many sets a second (0: all)
     for (int i = 1; i < argc; ++i) {
         const std::string a = argv[i];
         const bool more = i + 1 < argc;
@@ -205,6 +205,7 @@ int main(int argc, char **argv) {
         else if (a == "--ring" && more) ring_path = argv[++i];
         else if (a == "--record" && more) record = argv[++i];
         else if (a == "--record-for" && more) record_for = std::atof(argv[++i]);
+        else if (a == "--record-hz" && more) record_hz = std::max(0.0, std::atof(argv[++i]));
         else if (a == "--keep-presence" && more) keep_presence = std::atof(argv[++i]);
         else if (a == "--cams" && more) cams_arg = argv[++i];
         else if (a == "--bright" && more) bright_arg = argv[++i];
@@ -222,14 +223,15 @@ int main(int argc, char **argv) {
         else {
             std::printf("usage: %s [--seconds N] [--threads N] [--int8] [--status S] [--models DIR] [--nice N] [--no-publish]\n"
                         "          [--no-gestures] (hands for the cutouts only: no pinches or grips)\n"
-                        "          [--record DIR] [--record-for S] [--record-only] [--cpus 5,6,7] [--swap-sides]\n"
+                        "          [--record DIR] [--record-for S] [--record-hz N] [--record-only] [--cpus 5,6,7] [--swap-sides]\n"
                         "          [--keep-presence P] (0.5) [--ring PATH] (ft-camd's, or ft-ringplay's)\n"
                         "          [--cams auto|mono|color|all] (auto) [--bright all|color] (all) [--bright-on L] (40) [--bright-off L] (25)\n"
                         "          [--color-left color_video0|color_video3] [--color-crop subtract|none]\n"
                         "          [--pinch-begin M] (0.020) [--pinch-end M] (0.035) [--pinch-triangulated] [--pinch-palm-down MAX] (1: off)\n"
                         "          [--grip-begin R] (1.2) [--grip-end R] (1.45) [--gesture-log]\n"
                         "          [--contrast MODE|PALM/HAND] (clahe[:CLIP], none, stretch; default clahe:2/none)\n"
-                        "Recording saves every frame set for S seconds (120) to DIR/sets.bin, for ft-handreplay; SIGUSR1\n"
+                        "Recording saves every frame set (at most N a second with --record-hz) for S seconds (120) to DIR/sets.bin,\n"
+                        "for ft-handreplay; SIGUSR1\n"
                         "starts one in ~/.local/share/frametop/hands/rec-<time>. --record-only records without tracking, so it\n"
                         "can run beside a tracking ft-hands. With ft-camd --with-dark, recordings also get each\n"
                         "camera's newest dark frame, as <name>_dk; with --with-color, the color cameras' as color_video<N>.\n"
@@ -260,7 +262,7 @@ int main(int argc, char **argv) {
     Pinch pinch(pinch_params);
     Grip grip(grip_params);
     std::unique_ptr<Recorder> rec;
-    uint64_t rec_start = 0;
+    uint64_t rec_start = 0, rec_next_ns = 0;   // rec_next_ns: --record-hz's next set, capture clock
     auto start_recording = [&](const std::string &dir, std::string &e) {
         rec = std::make_unique<Recorder>();
         if (!rec->open(dir, e)) return rec.reset(), false;
@@ -490,7 +492,15 @@ int main(int argc, char **argv) {
                 if (!start_recording(dir + "/" + name, e)) std::fprintf(stderr, "%s\n", e.c_str());
             }
             if (rec) {   // about 80 MB/s; dark frames double that, color frames add 70 MB/s
-                if ((mono_ns() - rec_start) / 1e9 < record_for) {
+                const bool due = record_hz <= 0 || tmin >= rec_next_ns;   // --record-hz skips the sets between
+                if (due && record_hz > 0) rec_next_ns = tmin + uint64_t(1e9 / record_hz) - 5'000'000;
+                if ((mono_ns() - rec_start) / 1e9 >= record_for) {
+                    const size_t n = rec->written(), d = rec->dropped();
+                    rec.reset();   // writes out what's queued
+                    std::printf("recording done: %zu sets, %zu dropped\n", n, d);
+                    std::fflush(stdout);
+                    if (!track) break;
+                } else if (due) {
                     for (auto &[name, i] : dark) {   // the newest dark and color frames, as they are
                         fh_ring_slot_t meta;
                         const uint64_t n = ring.latest(i);
@@ -500,12 +510,6 @@ int main(int argc, char **argv) {
                                               meta.dqbuf_ns});
                     }
                     rec->add(frames);
-                } else {
-                    const size_t n = rec->written(), d = rec->dropped();
-                    rec.reset();   // writes out what's queued
-                    std::printf("recording done: %zu sets, %zu dropped\n", n, d);
-                    std::fflush(stdout);
-                    if (!track) break;
                 }
             }
             if (!track && rec && status > 0 && (mono_ns() - t_status) / 1e9 >= status) {