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Export a VRS file to MP4

The vrs_to_mp4 script enables you to create an MP4 video from a Project Aria VRS recording. By default, it uses RGB as well as audio streams (if present). The MP4 video will have the same framerate as the RGB stream in the VRS file and use H264 and MP3 7 (or 2) channel encoding for video and audio. If a dropped frame is present in the VRS recording (a frame could be missing at a given expected timestamp), the closest valid frame will be copied over until the next valid frame.

vrs_to_mp4 generates a recording preview

This script provides video preview. It is not designed to create a video file suitable for Computer Vision applications.

Install dependencies​

python3 -m pip install projectaria_tools moviepy

Usage​

vrs_to_mp4 tool is available via command line or through Python as a library.

from projectaria_tools.utils.vrs_to_mp4_utils import convert_vrs_to_mp4
convert_vrs_to_mp4(input_vrs, output_video, log_folder, down_sample_factor)

MISC​

Extract VRS timestamps from MP4​

Historically, when VRS files were converted to MP4, accurate timestamp information was lost. To maintain compatibility with the rest of our tooling, this tool now logs a VRS timestamp for each MP4 frame. VRS timestamps are saved to the MP4's metadata and are measured in nanoseconds. Now for every MP4 extracted using vrs_to_mp4 tools, this timestamp is conveniently saved as a metadata.

To extract the vrs timestamps, use the get_timestamp_from_mp4 function. The resulting timestamp is in TimeDomain.DEVICE_TIME

from projectaria_tools.utils.vrs_to_mp4_utils import get_timestamp_from_mp4
vrs_device_timestamps_nanoseconds = get_timestamp_from_mp4(mp4_file)

Calibration for upright RGB​

The output RGB frames in the MP4 file are rotated upright (clockwise 90 degrees). The camera calibration will be changed after such rotation and can be obtained using the following interface.

from projectaria_tools.utils.calibration_utils import (
    rotate_upright_image_and_calibration,
)
upright_image, upright_calibration = rotate_upright_image_and_calibratio(original_rgb_image, rgb_camera_calibration)