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prepare_sot_dataset.py

Prepares an evaluator-ready Single Object Tracking (SOT) dataset from a benchmark JSON/JSONL file and source camera videos hosted on Hugging Face.


Files

File Description
sot_benchmark.jsonl Benchmark file defining all evaluation sequences — scene, camera, object, init bounding box, and canonical 8-frame IDs.
prepare_sot_dataset.py Script that downloads source videos and extracts frames into an evaluator-ready directory.

Overview

The script:

  1. Reads sot_benchmark.jsonl (or a custom benchmark file) describing SOT sequences (scene, camera, target bounding box, frame IDs).
  2. Downloads the corresponding source .mp4 files from the nvidia/PhysicalAI-SmartSpaces Hugging Face dataset (or a custom repo).
  3. Extracts the requested frames with ffmpeg.
  4. Annotates the initialization frame with a bounding-box overlay (f00_ann.png) and saves a cropped target thumbnail (crop.png).
  5. Writes a sequence_meta.json per sequence.
  6. Produces a gt_requests.json manifest. Ground-truth bounding boxes are never written to the output directory — see GT Request Submission below.

Prerequisites

Requirement Notes
Python 3.8+
ffmpeg Must be on PATH (or in a few well-known locations).
huggingface_hub pip install huggingface_hub
opencv-python or Pillow Used for bbox drawing and cropping. opencv-python is preferred.
HF access token Read access to the source video dataset.
pip install huggingface_hub opencv-python

Hugging Face Authentication

A token with read access to nvidia/PhysicalAI-SmartSpaces is required. Pass it in one of two ways:

# Option A – command-line flag
--hf-token hf_xxxxxxxxxxxx

# Option B – environment variable (recommended for scripts/CI)
export HF_TOKEN=hf_xxxxxxxxxxxx

Input Formats

The script accepts four flavors of JSON / JSONL input.

1. Standard benchmark JSON/JSONL (most common)

[
  {
    "seq_id": "Warehouse_016__Camera_11__5600__obj353",
    "scene": "Warehouse_016",
    "camera": "Camera_11",
    "object_id": "353",
    "object_type": "Robot",
    "init_frame_id": 5600,
    "init_bbox": [799.0, 601.9, 918.8, 956.5],
    "canonical_frame_ids": [5600, 5615, 5630, 5645, 5660, 5675, 5690, 5705],
    "clip_fps": 30.0
  }
]
  • init_bbox — normalized coordinates in thousandths of image dimensions ([x1, y1, x2, y2] where 1000 = full width/height).
  • canonical_frame_ids — preferred source-video frame indices to extract. When provided and long enough, they take priority over the stride calculation.

2. Benchmark JSONL with explicit GT

{"seq_id": "...", "canonical_frame_ids": [...], "gt_bboxes": {"5600": [...]}}

3. Dataset JSONL (metadata + conversations)

{
  "id": "...",
  "metadata": {"scene": "...", "camera": "...", "init_bbox": [...], ...},
  "conversations": [{"role": "user", "value": "..."}, {"role": "assistant", "value": "{\"5600\": [...]}"}]
}

4. Sequence-only JSON/JSONL

{"id": "...", "scene": "...", "camera": "...", "source_frame_ids": [...], "init_bbox": [...]}

Output Structure

<output_dir>/
  gt_requests.json            # submit this to us to receive GT annotations (see below)
  <seq_id>/
    frames/
      f00.png                 # initialization frame
      f00_ann.png             # initialization frame with target bbox drawn
      crop.png                # cropped target region
      f01.png
      f02.png
      ...
      f{N-1}.png
    sequence_meta.json        # per-sequence metadata

sequence_meta.json fields

Field Description
frame_ids Source-video frame indices that were extracted
init_bbox Target bounding box (thousandths)
label Human-readable sequence label
scene / camera Source identifiers
object_id / object_type Target object metadata
stride Frame stride used during extraction
nframes Number of frames extracted
clip_fps Frame rate of the source video
gt_available Always false (GT is private)

Usage

Minimal

python scripts/tracking/prepare_sot_dataset.py \
    --benchmark sot_benchmark.jsonl \
    --output-dir ./SOT_prepared_8f

Extract 32 frames per sequence

python scripts/tracking/prepare_sot_dataset.py \
    --benchmark sot_benchmark.jsonl \
    --output-dir ./SOT_prepared_32f \
    --nframes 32

Custom frame stride

python scripts/tracking/prepare_sot_dataset.py \
    --benchmark sot_benchmark.jsonl \
    --output-dir ./SOT_prepared \
    --nframes 16 \
    --stride 10

Process only specific sequences

python scripts/tracking/prepare_sot_dataset.py \
    --benchmark sot_benchmark.jsonl \
    --output-dir ./SOT_prepared \
    --sequences Warehouse_016__Camera_11__5600__obj353 Warehouse_016__Camera_05__704__obj352

Use a custom Hugging Face cache directory

python scripts/tracking/prepare_sot_dataset.py \
    --benchmark sot_benchmark.jsonl \
    --output-dir ./SOT_prepared \
    --hf-token hf_xxxxxxxxxxxx \
    --hf-cache-dir /data/hf_cache

Windows (PowerShell)

python scripts/tracking/prepare_sot_dataset.py `
    --benchmark sot_benchmark.jsonl `
    --output-dir .\SOT_prepared_8f `
    --hf-token hf_xxxxxxxxxxxx

Command-Line Reference

Argument Required Default Description
--benchmark Yes Path to the input benchmark JSON or JSONL file.
--output-dir Yes Directory where prepared sequences are written. Created if it does not exist.
--nframes No 8 Number of frames to extract per sequence.
--stride No auto Source-video frame stride. When omitted, auto-computed from clip_end_frame or taken directly from canonical_frame_ids.
--hf-token No* $HF_TOKEN Hugging Face access token. Falls back to the HF_TOKEN environment variable.
--hf-cache-dir No HF default Cache directory for downloaded videos.
--repo-id No nvidia/PhysicalAI-SmartSpaces Hugging Face dataset repository.
--repo-subdir No MTMC_Tracking_2025 Subdirectory inside the repository.
--sequences No all Space-separated list of seq_id values to prepare. All others are skipped.

* Required in practice unless HF_TOKEN is set in the environment.


Resuming an Interrupted Run

The script checks how many frames already exist in each sequence's frames/ directory. If the count equals or exceeds --nframes, that sequence is skipped automatically. You can safely re-run the command after an interruption; only incomplete sequences will be processed.


Frame Stride Logic

Frames are selected using this priority order:

  1. canonical_frame_ids in the benchmark — used directly when the list has at least --nframes entries and --stride is not explicitly set.
  2. --stride — fixed stride supplied by the user.
  3. Auto — computed as min(15, (clip_end_frame - init_frame_id) / (nframes - 1)), capped at the default stride of 15.

Train / Val Split

The script infers the dataset split from the scene name:

  • Warehouse_000Warehouse_014train
  • Warehouse_015 and above → val

This determines which subdirectory (train/ or val/) is used when constructing the download path on Hugging Face.


GT Request Submission

The sot_benchmark.jsonl file defines the canonical 8-frame evaluation sequences with fixed frame IDs. If you use the default settings (--nframes 8 without --stride), no submission is needed — the benchmark frames are already known.

If you run a custom variant (e.g. --nframes 16, --nframes 32, --nframes 64, or a custom --stride), the script will produce a gt_requests.json file in your output directory once preparation is complete. Submit this file back to us so we can look up and return the ground-truth annotations for your chosen frames.

Send gt_requests.json to: (benchmark contact TBD)


Evaluator Integration

After preparation, point your evaluator config at the output directory:

{
  "prepared_data_dir": "./SOT_prepared_8f"
}

Troubleshooting

Problem Fix
ERROR: ffmpeg not found Install ffmpeg and add it to PATH, or place it in /usr/bin/ffmpeg.
401 Unauthorized from Hugging Face Check that --hf-token / HF_TOKEN is set and has read access to the repo.
Download retries / timeouts The script retries up to 4 times with back-off. Check your network connection.
Bounding boxes not drawn Install opencv-python or Pillow. Without either, the script copies the raw frame without annotation.
Sequence not found in output Verify the seq_id value; use --sequences <seq_id> to test a single entry.