EuRoC player

Source references are to uwrealitylabs/standalone-monado-driver, branch dev at 6bbefe8, relative to src/xrt/.

Monado's dataset replay source. It reads a dataset in EuRoC format and plays camera frames, IMU samples and ground truth into sinks, in real time or faster. It implements xrt_fs (a frame server, see Sinks), so to every consumer it looks like a live camera-and-IMU source. Code: drivers/euroc/euroc_player.cpp; interface drivers/euroc/euroc_interface.h; built with XRT_BUILD_DRIVER_EUROC.

Dataset format

EuRoC is the layout of the ETH EuRoC MAV datasets, also used by the Monado SLAM datasets (egocentric, recorded on real XR headsets; preferred for us over the drone-based originals).

<dataset>/mav0/
  cam0/data.csv, cam0/data/<timestamp_ns>.png      one folder per camera
  cam1/...
  imu0/data.csv                                     timestamp, gyro xyz, accel xyz
  <gt device>/data.csv                              timestamp, px py pz, qw qx qy qz

The player looks for ground truth in vicon0, mocap0, state_groundtruth_estimate0 or leica0 (euroc_player.cpp:205), or the folder named by EUROC_GT_DEVICE_NAME.

Where it sits

It replaces the capture layer. Everything above the sinks runs unchanged.

Live:    our capture (V4L2 cameras + IMU reader + clock mapping) ─┐
                                                                   ├─ xrt_slam_sinks ─► t_slam ─► VIT/Basalt
Replay:  EuRoC player ─────────────────────────────────────────────┘                    ▲ get_tracked_pose
                                                                          our HMD xrt_device ◄── core

Replaced	Still real
Camera capture, IMU reading, hardware-to-monotonic clock mapping, our calibration	t_slam, VIT/Basalt, our device's pose composition, Monado core, compositor, apps

How a driver interfaces with it

Two calls. Both live in the builder's open function, in place of creating live capture.

Create: euroc_player_create(xfctx, path, &config) (euroc_player.cpp:978) returns an xrt_fs already registered with the frame context (:1045). Fill config first with euroc_player_fill_default_config_for (euroc_interface.h:86), which reads the dataset to find its camera count and whether it has colour and ground truth.
Start: xrt_fs_slam_stream_start(player, sinks) (euroc_player.cpp:779). The player stores the sinks and its playback thread pushes frames (:694), IMU samples (:738) and, if enabled, ground truth into them.

Sketch of a replay branch in our builder (proposed, not implemented; the task is described in SLAM tracer bullet from EuRoC):

#include "euroc/euroc_interface.h"
#include "tracking/t_tracking.h"

struct euroc_player_config ep_cfg;
euroc_player_fill_default_config_for(&ep_cfg, replay_path);
ep_cfg.playback.play_from_start = true;      // default waits for the debug GUI

struct t_slam_tracker_config st_cfg;
t_slam_fill_default_config(&st_cfg);
st_cfg.cam_count = ep_cfg.playback.cam_count;
st_cfg.submit_from_start = true;             // default discards everything
st_cfg.slam_config = basalt_toml_for_dataset; // e.g. Basalt's msdmi.toml

struct xrt_tracked_slam *xts = NULL;
struct xrt_slam_sinks *sinks = NULL;
t_slam_create(xfctx, &st_cfg, &xts, &sinks);
t_slam_start(xts);

struct xrt_fs *src = euroc_player_create(xfctx, replay_path, &ep_cfg);
xrt_fs_slam_stream_start(src, sinks);
// Give xts to the HMD device; it queries xrt_tracked_slam_get_tracked_pose().

The same sequence, minus the device, is drivers/euroc/euroc_runner.c:91–115.