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Project Aria VRS Data Format

Project Aria data is stored in VRS, which is optimized to record and playback streams of multi-modal sensor data, such as images, audio, and other discrete sensors (IMU, temperature, etc.). In this page, we will introduce some basic concepts of VRS file format in Aria recordings. Users are referred to the official VRS repo documentation page for details.

Aria data streams​

In VRS, data is organized by streams, each storing data measured by a specific sensor, or calculated from an on-device machine perception algorithm.

The VRS streams are uniquely identified by their StreamId, each consisting of a RecordableTypeId to categorize the type of the stream data, and an InstanceId for identifying the specific instance of the sensor. For example, the first SLAM camera is identified with StreamId = 1201-1, where 1201 is the numerical ID for SLAM camera data type, and -1 identifies the first of all the SLAM cameras.

For convenience, we also provide a short label for each stream within our library projectaria-tools, which provides a human-readable way to access the data. See this page to learn more.

Aria sensor data and configuration​

Sensor data includes:

  • Sensor readout
  • Timestamps
  • Acquisition parameters (exposure and gain settings)
  • Conditions (e.g. temperature) during data collection

Most sensor data of a single stream and at a specific timestamp is stored as a single piece, except for image and audio.

How data is stored for image recordings​

  • Each camera stores a single image frame at a time.
  • The image frame contains two parts, the image itself and the image record.
    • The image record stores timestamps, frame id, and acquisition parameters, such as exposure and gain. This avoids having to read image data to get the information in the record.

How data is stored for audio recordings​

  • The audio data is grouped into data chunks of 4096 audio samples from all microphones.
  • Each chunk contains two parts, the data part for the audio signal, and the report part for the timestamps of each audio signal.

Sensor configuration blob​

The sensor configuration blob stores the static information of a stream. Common sensor configuration stores information, such as sensor model, sensor serial (if available) as well as frame rate. Stream-specific information, such as image resolution, is also stored in configurations.

Go to this python tutorial to learn how to access and use the sensor data using Python data utilities. Go to the source code for the detailed implementation of sensor data and configurations.