This guide will walk you through the process of downloading a sample MCAP file, inspecting it to find video topics, and ingesting the video into Nominal.

Prerequisites

Make sure you have the following Python packages installed:

• huggingface_hub
• mcap
• nominal

You can install them all using:

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pip3 install huggingface_hub mcap nominal

Step 1: Download the Sample MCAP File

First, download a sample MCAP file using the huggingface_hub library.

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from huggingface_hub import hf_hub_download
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video_path = hf_hub_download(
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    repo_id="nominal-io/xplane",
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    filename="xplane.mcap",
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    repo_type='dataset'
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)
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print(f"File saved to: {video_path}")

Step 2: Inspect the MCAP File to Find Video Topics

Next, use the mcap library to inspect the MCAP file and identify available video topics.

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from mcap.reader import make_reader
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with open(video_path, "rb") as f:
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    reader = make_reader(f)
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    schemas = reader.get_summary().schemas
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    channels = reader.get_summary().channels
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    def schema_name(channel):
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        schema = schemas.get(channel.schema_id)
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        if not schema:
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            return None
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        return schema.name
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    video_topics = [
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        channel.topic for channel in channels.values()
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        if schema_name(channel) == "foxglove.CompressedVideo"
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    ]
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    print("Video topics: ", video_topics)

This script will output the video topics available in the MCAP file, which you’ll use in the next step.

Step 3: Connect to Nominal

Before ingesting the video, ensure you’re connected to Nominal.

When using the Nominal client library, there are two primary ways of authenticating:

$
$ python -m nominal auth set-token
>
>
# Alternatively, use the globally installed CLI
>
$ nom auth set-token

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import nominal
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# Simply grab the "default" client using your stored credentials
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client = nominal.get_default_client()
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# Get details about the currently logged-in user to validate authentication
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# Will display an object like: `User(display_name='your_email@your_company.com', ...)`
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print(client.get_user())

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import nominal
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# Set login details for the user
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nominal.set_token("<insert api key>")
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# Get an instance of the client using provided credentials
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client = nominal.get_default_client()
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# Get details about the currently logged-in user to validate authentication
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# Will display an object like: `User(display_name='your_email@your_company.com', ...)`
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print(client.get_user())

Step 4: Ingest the Video

Finally, upload the video to Nominal using a topic from the list.

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import nominal as nm
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video = nm.upload_mcap_video(video_path, "video")
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print(video)