Python Client

vitallens is the official Python client for the VitalLens API, a service for estimating physiological vital signs like heart rate, respiratory rate, and heart rate variability (HRV) from facial video.

The library provides:

A simple interface to the powerful VitalLens API for state-of-the-art vital sign estimation.
Implementations of classic rPPG algorithms (POS, CHROM, G) for local, API-free processing.
Support for video files and in-memory video as np.ndarray
Fast face detection if required - you can also pass existing detections

Using a different language or platform? We also have a JavaScript client and iOS app.

Installation

You can install the library using pip:

pip install vitallens

Quickstart

To get started, you'll need an API key for the VITALLENS methods. You can get a free key from the rouast.com API page.

Here's a quick example of how to analyze a video file and get vital signs:

import vitallens

# Your API key from https://www.rouast.com/api
API_KEY = "YOUR_API_KEY"

# Initialize the client.
# Method.VITALLENS automatically selects the best available model for your plan.
vl = vitallens.VitalLens(method=vitallens.Method.VITALLENS, api_key=API_KEY)

# Analyze a video file
# You can also pass a numpy array of shape (n_frames, height, width, 3)
video_path = 'path/to/your/video.mp4'
results = vl(video_path)

# Print the results
if results:
  vital_signs = results[0]['vital_signs']
  hr = vital_signs.get('heart_rate', {}).get('value')
  rr = vital_signs.get('respiratory_rate', {}).get('value')
  sdnn = vital_signs.get('hrv_sdnn', {}).get('value')

  print(f"Heart Rate: {hr:.1f} bpm")
  print(f"Respiratory Rate: {rr:.1f} rpm")
  if sdnn is not None: print(f"HRV (SDNN): {sdnn:.1f} ms")

Troubleshooting

General prerequisites are python>=3.9 and ffmpeg installed and accessible via the $PATH environment variable. On Windows, Microsoft Visual C++ must also be installed.

On newer versions of Python you may face the issue that the dependency onnxruntime cannot be installed via pip. If you are using conda, you can try installing it via conda install -c conda-forge onnxruntime, and then run pip install vitallens again. Otherwise try using Python 3.9, 3.10, or 3.11.

How to use

Configuring `vitallens.VitalLens`

To start using vitallens, first create an instance of vitallens.VitalLens. It can be configured using the following parameters:

Parameter	Description	Default
method	Inference method. {e.g., `Method.VITALLENS`, `Method.POS`}	`Method.VITALLENS`
mode	Operation mode. {`Mode.BATCH` for indep. videos or `Mode.BURST` for video stream}	`Mode.BATCH`
api_key	Usage key for the VitalLens API (required for `Method.VITALLENS`)	`None`
detect_faces	`True` if faces need to be detected, otherwise `False`.	`True`
estimate_rolling_vitals	Set `True` to compute rolling vitals (e.g., `rolling_heart_rate`).	`True`
fdet_max_faces	The maximum number of faces to detect (if necessary).	`1`
fdet_fs	Frequency [Hz] at which faces should be scanned - otherwise linearly interpolated.	`1.0`
export_to_json	If `True`, write results to a json file.	`True`
export_dir	The directory to which json files are written.	`.`

Methods

You can choose from several rPPG methods:

Method.VITALLENS: The recommended method. Uses the VitalLens API and automatically selects the best model for your API key (e.g., VitalLens 2.0 with HRV support).
Method.VITALLENS_2_0: Forces the use of the VitalLens 2.0 model.
Method.VITALLENS_1_0: Forces the use of the VitalLens 1.0 model.
Method.VITALLENS_1_1: Forces the use of the VitalLens 1.1 model.
Method.POS, Method.CHROM, Method.G: Classic rPPG algorithms that run locally and do not require an API key.

Estimating vitals

Once instantiated, vitallens.VitalLens can be called to estimate vitals. In Mode.BATCH calls are assumed to be working on independent videos, whereas in Mode.BURST we expect the subsequent calls to pass the next frames of the same video (stream) as np.ndarray. Calls are configured using the following parameters:

Parameter	Description	Default
video	The video to analyze. Either a path to a video file or `np.ndarray`. More info here.
faces	Face detections. Ignored unless `detect_faces=False`. More info here.	`None`
fps	Sampling frequency of the input video. Required if video is `np.ndarray`.	`None`
override_fps_target	Target frequency for inference (optional - use methods's default otherwise).	`None`
export_filename	Filename for json export if applicable.	`None`

Understanding the results

vitallens returns estimates of the following vital signs if using Mode.BATCH with a minimum of 16 frames:

Name	Type	Returned if
`ppg_waveform`	Continuous waveform	Always
`heart_rate`	Global value	Video at least 5 seconds long
`rolling_heart_rate`	Continuous values	Video at least 10 seconds long
`respiratory_waveform`	Continuous waveform	Using `VITALLENS`, `VITALLENS_1_0`, `VITALLENS_1_1`, or `VITALLENS_2_0`
`respiratory_rate`	Global value	Video at least 10 seconds long and using `VITALLENS`, `VITALLENS_1_0`, `VITALLENS_1_1`, or `VITALLENS_2_0`
`rolling_respiratory_rate`	Continuous values	Video at least 30 seconds long and using `VITALLENS`, `VITALLENS_1_0`, `VITALLENS_1_1`, or `VITALLENS_2_0`
`hrv_sdnn`	Global value	Video at least 20 seconds long and using `VITALLENS` or `VITALLENS_2_0`
`hrv_rmssd`	Global value	Video at least 20 seconds long and using `VITALLENS` or `VITALLENS_2_0`
`hrv_lfhf`	Global value	Video at least 55 seconds long and using `VITALLENS` or `VITALLENS_2_0`
`rolling_hrv_sdnn`	Continuous values	Video at least 60 seconds long and using `VITALLENS` or `VITALLENS_2_0`
`rolling_hrv_rmssd`	Continuous values	Video at least 60 seconds long and using `VITALLENS` or `VITALLENS_2_0`
`rolling_hrv_lfhf`	Continuous values	Video at least 60 seconds long and using `VITALLENS` or `VITALLENS_2_0`

Note that rolling metrics are only computed when estimate_rolling_vitals=True.

The estimation results are returned as a list. It contains a dict for each distinct face, with the following structure:

[
  {
    'face': {
      'coordinates': <Face coordinates for each frame as np.ndarray of shape (n_frames, 4)>,
      'confidence': <Face live confidence for each frame as np.ndarray of shape (n_frames,)>,
      'note': <Explanatory note>
    },
    'vital_signs': {
      'heart_rate': {
        'value': <Estimated global value as float scalar>,
        'unit': <Value unit>,
        'confidence': <Estimation confidence as float scalar>,
        'note': <Explanatory note>
      },
      <other vitals...>
    },
    "message": <Message about estimates>
  },
  { 
    <same structure for face 2 if present>
  },
  ...
]

Examples to get started

Live test with webcam in real-time

Test vitallens in real-time with your webcam using the script examples/live.py. This uses Mode.BURST to update results continuously (approx. every 2 seconds for Method.VITALLENS). Some options are available:

method: Choose from [VITALLENS, POS, G, CHROM] (Default: VITALLENS)
api_key: Pass your API Key. Required if using method=VITALLENS.

May need to install requirements first: pip install opencv-python

python examples/live.py --method=VITALLENS --api_key=YOUR_API_KEY

Compare results with gold-standard labels using our example script

There is an example Python script in examples/test.py which uses Mode.BATCH to run vitals estimation and plot the predictions against ground truth labels recorded with gold-standard medical equipment. Some options are available:

method: Choose from [VITALLENS, POS, G, CHROM] (Default: VITALLENS)
video_path: Path to video (Default: examples/sample_video_1.mp4)
vitals_path: Path to gold-standard vitals (Default: examples/sample_vitals_1.csv)
api_key: Pass your API Key. Required if using method=VITALLENS.

May need to install requirements first: pip install matplotlib pandas

For example, to reproduce the results from the banner image on the VitalLens API Webpage:

python examples/test.py --method=VITALLENS --video_path=examples/sample_video_2.mp4 --vitals_path=examples/sample_vitals_2.csv --api_key=YOUR_API_KEY

This sample is kindly provided by the VitalVideos dataset.

Use VitalLens API to estimate vitals from a video file

First, we create an instance of vitallens.VitalLens named vl while choosing vitallens.Method.VITALLENS as estimation method and providing the API Key.

Then, we can call vl to estimate vitals. In this case, we are estimating vitals from a video located at video.mp4. The result contains the estimation results.

from vitallens import VitalLens, Method

vl = VitalLens(method=Method.VITALLENS, api_key="YOUR_API_KEY")
result = vl("video.mp4")

Use VitalLens API on an `np.ndarray` of video frames

First, we create an instance of vitallens.VitalLens named vl while choosing vitallens.Method.VITALLENS as estimation method and providing the API Key.

Then, we can call vl to estimate vitals. In this case, we are passing a np.ndarray my_video_arr of shape (n, h, w, c) and with dtype np.uint8 containing video data. We also have to pass the frame rate my_video_fps of the video.

The result contains the estimation results.

from vitallens import VitalLens, Method

my_video_arr = ...
my_video_fps = 30
vl = VitalLens(method=Method.VITALLENS, api_key="YOUR_API_KEY")
result = vl(my_video_arr, fps=my_video_fps)

Run example script with Docker

If you encounter issues installing vitallens dependencies directly, you can use our Docker image, which contains all necessary tools and libraries. This docker image is set up to execute the example Python script in examples/test.py for you.

Prerequisites

Docker installed on your system.

Usage

Clone the repository

git clone https://github.com/Rouast-Labs/vitallens-python.git && cd vitallens-python

Build the Docker image

docker build -t vitallens .

Run the Docker container

To run the example script on the sample video:

docker run vitallens \          
  --api_key "your_api_key_here" \
  --vitals_path "examples/sample_vitals_2.csv" \
  --video_path "examples/sample_video_2.mp4" \
  --method "VITALLENS"

You can also run it on your own video:

docker run vitallens \          
  --api_key "your_api_key_here" \
  --video_path "path/to/your/video.mp4" \
  --method "VITALLENS"

View the results

The results will print to the console in text form.

Please note that the example script plots won't work when running them through Docker. To to get the plot as an image file, run:

docker cp <container_id>:/app/results.png .

Build

To build:

python -m build

Linting and tests

Before running tests, please make sure that you have an environment variable VITALLENS_DEV_API_KEY set to a valid API Key. To lint and run tests:

flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
pytest

Disclaimer

vitallens provides vital sign estimates for general wellness purposes only. It is not intended for medical use. Always consult with your doctor for any health concerns or for medically precise measurement.

See also our Terms of Service for the VitalLens API and our Privacy Policy.

License

This project is licensed under the MIT License.